notes Flashcards

Question

Structural Limits To Flexibility

Answer 1

1. Bony structure of the joint - can’t be changed by a flexibility program 2. Ligaments 3. Joint capsules 4. Muscle-tendon unit - muscle and its fascial sheaths - the major focus of stretching exercises is the elongation of this tissue.

Answer 2

The somatotype is a quantitative description of the present structure and composition of the body. This method of physique classification was developed by W.H. Sheldon in the 1920's to 1950's. The real value of somatotyping lies in its contribution toward a better understanding of the individual.

Answer 3

Body image - the picture an individual has of her own body that she forms in her mind. Individuals assign qualities of size, shape, and attractiveness to their bodies in terms of personalized standards that may bear little relation to actual body characteristics. Some people love and parade their bodies; others are ashamed of their bodies and hide them. The primary determinants of body appearance are (a) the skeleton (b) muscle (c) fat

Answer 4

Sheldon designated three primary components of body build: (1) Endomorphy - refers to the relative predominance of soft roundness throughout the body. (2) Mesomorphy - refers to relative predominance of muscle, bone, and connective tissue. (3) Ectomorphy - refers to the relative predominance of linearity and fragility. Sheldon rated each component on a seven-point scale to indicate it's relative contribution to the total physique. This three numeral rating of a physique is called the "somatotype". First numeral = endomorphy Second numeral = mesomorphy Third numeral = ectomorphy Most physiques are dominated by two components. 641 = mesomorphic endomorph 461 = endomorphic mesomorph 244 = mesomorph - ectomorph 333 = balanced

Answer 5

On a somatoplot, the distribution of female physique types differs from the male distribution of physique types – sexual dimorphism. Females are more endomorphic and less mesomorphic than males. 1976 – 1978 Canadian data. Refer to page in 3-18 in Laboratory Manual. Average somatotypes for males and females aged 15 to 60 years: Males: 3.9 – 5.2 – 1.9 Females: 4.7 – 4.0 – 2.2

Answer 6

Both male and female athletes are more mesomorphic and less endomorphic than non-athletes of the same age. There are characteristic somatoplot distributions for each sport. The higher the level of sport the lower the variation in somatoplot distribution. Some sports are more tolerant of somatotype variation than other sports. A high mesomorphy is positively correlated with physical fitness tests and endomorphy is negatively correlated. Strength and speed-dependent athletes are more mesomorphic and less ectomorphic than distance-dependent athletes. Very seldom do men and women low in mesomorphy succeed at a high level in sports.

Answer 7

Several systems of somatotyping have been developed. The Sheldon method and the Heath-Carter method have been the most widely used. The Heath-Carter method has been extensively used on samples of athletes. In the Heath-Carter method, the rating scale was opened at the top end, from 7 to 12, to accommodate extreme body types. The somatotype doesn’t tell you anything about a person’s height, or about body proportionality - trunk length vs leg length, etc.

Answer 8

is a theory based upon the idea that the assessment of the person's outer appearance, primarily the face, may give insights into one's character or personality.

Answer 9

two-component model - the amount of fat and fat-free mass of which the body is composed. Fat-free mass is primarily composed of bone, muscle, vital organs, and connective tissue. Four-component model - fat, protein, mineral, water

Answer 10

quantitative measures of selected human landmarks.

Answer 11

•Suitable body composition is important for health. •Establish reasonable fatness ranges for athletes in various sports •Accurate measures of body composition are needed to develop sound weight reduction programs •Knowledge of bone mineral content in women and children is important. •Monitor changes in body composition associated with disease.

Answer 12

Essential fat - fat that is required for normal physiological functioning - structural components of cell membranes, required for the synthesis of certain hormones, transport of fat-soluble vitamins, etc. Storage fat - fat that is stored in adipose tissue for energy supply purposes. It is located underneath the skin, in the abdominal cavity, and around certain organs.

Answer 13

level ll: molecular level lll: cellular level lv: tissue level v: whole body

Answer 14

The average male is taller, heavier, has a larger muscle mass, and a lower total body fat content. Female has sex specific fat depots in the breasts, pelvic and thigh regions, and probably other areas. For reference male and female, age 20 - 24: Storage fat - female = 15% - male = 12 % Essential fat - female = 12 % - male = 3 %

Answer 15

obesity - excess fat is deposited on the upper torso and around the abdomen. Male type obesity appears to be associated with higher health risks.

Answer 16

obesity - excess fat is deposited below the waist in the thighs, hips, and buttocks, i.e., pear shape.

Answer 17

Weight gain and obesity occur when energy intake exceeds energy expenditure. Data from overfeeding experiments with identical twins demonstrate that some individuals are more at risk than others to gain fat when energy intake surplus is maintained at the same level for everyone and when all subjects are confined to a sedentary lifestyle. NEAT – non-exercise activity thermogenesis. It is the energy expended by physical activities other than planned exercise – sitting, standing, walking, fidgeting, etc. In a recent research study, obese participants were seated for 164 minutes longer per day than were lean participants.

Answer 18

Direct methods - chemical analysis of human cadavers Indirect methods - noninvasive techniques used on living persons

Answer 19

Desirable weight with regard to the lowest death rates is predicted from tables that have been developed by insurance actuaries. Criticisms: (1) These tables do not consider body composition. (2) Most of the data in the 1983 Metropolitan Life Insurance Height-Weight tables come from white, middle-class, U.S. adults aged 25 to 59 years. This is not a representative sample of the general North American population. (3) No accepted method has been devised for determining frame size.

Answer 20

structural plants + reproductive plants + animal plants DQ is proportionate to brain metabolic rate The brain is about 2 % of body weight yet accounts for about 20 % of resting metabolic rate using less energy on the rest of the body and feeding our brain

Answer 21

Density = mass/volume. Body density will vary with the amount of body fat. After body density has been determined using one of the above methods, use an equation to determine percent body fat. These equations make two basic assumptions: (1) The human body has two compartments - fat and nonfat (2) Each of these compartments has densities which are known constants. Assume that fat has a density of 0.90 g/mL and nonfat a density of 1.10 g/mL.

Answer 22

For decades hydrostatic weighing has been used as a universal method for validating skinfold caliper formulae and all other methods, i.e., it has been used as the "gold standard". Problems:- cadaver studies (Brussels cadaver study, 1984) have shown that the density of the nonfat compartment varies as a function of age, sex, and racial group. Therefore, a nonfat density value of 1.10 g/mL is not universally applicable. Conclusion - densitometry should not be used as a universal criterion for prediction of percent fat. Equations based on four component models are preferred.

Answer 23

Body Mass Index (BMI) - used as an indicator of obesity. This index uses the body mass (kg) divided by the height (meters) squared. Recent research evidence indicates that these BMI cut-off points may need revision because the relationship between BMI and body composition, and between indices of fat distribution and the actual amount of visceral fat may differ across ethnic groups. For example, Asian populations have a higher body fat percentage at a lower BMI compared to Caucasians. Criticism - BMI does not differentiate body composition. BMI of Mike Tyson = 31

Answer 24

BMI less than 18.5 = underweight BMI of 25.0 to 29.9 = overweight BMI of 30 or 34.9 = obese class 1 BMI of 35 or 39.9 = obese class 2 BMI of 40 and higher = extreme obesity The prevalence of overweight and obesity amongst Canadian children and adults has increased significantly in the past 20 years. From 1981 to 1996, the prevalence of obesity in children tripled from 5 % to 15.5 %.

Answer 25

Rationale - a relationship exists between the fat located in the depots directly beneath the skin and internal body fat and body density. There are basically two ways to use fatfolds: (1) Use the sum of a number of skinfolds as an indication of relative fatness among individuals. Also compare "before" and "after" in the same individual. (2) Use fatfolds in conjunction with equations or tables to predict percent body fat. Skinfold caliper formulae to predict percent fat are site and sample specific.

Answer 26

(1) Constant densities in a two-compartment model (2) Proper identification of measurement site and proper measurement technique (3) Constant compressibility of the skinfold (4) Fixed adipose tissue patterning (5) Fixed proportion of internal to external fat

Answer 27

1) Population specific equations - developed from relatively small, homogeneous (age, sex, state of training, fatness) samples. Their application is limited to that subsample. Example – Sloan, Yuhasz (2) Generalized equations - developed from large, heterogeneous samples. These equations have a wider application in terms of age, and fatness. However, these equations should be used cautiously with unique populations such as extremely obese individuals and professional football players. Example - Jackson and Pollock, Durnin & Womersley, Peterson, Wang Even when the correct equation is used and the measurements are performed correctly, prediction of percent fat from skinfold measurements has an error of about 3-4 %.

Answer 28

Used by CDC, WHO, etc Many relations to health Used also for growth and development Measures are easy to take Measures are cheap Measures are reliable Measures are objective It is reasonably independent of height

Answer 29

This method requires the consideration of three different indicators for a comprehensive assessment of body weight, adiposity, and fat distribution. (1) Body mass index – is the subject overweight? (2) Sum of 5 skinfolds - triceps, biceps, subscapular, iliac crest, and medial calf. Is the subject over-fat? (3) Waist girth – is the subject high in visceral adiposity – male type obesity?

Answer 30

Adiposity rating, proportional weight rating, stanine scale

Answer 31

Electrical impedance units are used to measure the electrical resistance of the body. Impedance is greater in adipose tissue (14 - 22 % water) than in bone and muscle (71 - 75 % water). Attach electrodes to the subject. A low level electrical current (500 to 800 microamps at 50 kHz) is passed through the subject’s body. The higher the electrical resistance, the more fat the subject has.

Answer 32

NIR is still in the developmental stages and there is much skepticism surrounding the use of NIR to assess body composition. Principle - the degree of infrared light absorbed and reflected is related to the composition of the tissues. Optical densities are linearly related to subcutaneous and total body fat. The biceps is the best single site for estimating body fat using this method.

Answer 33

1. Dual energy X-ray absorptiometry – widely used for performing bone mineral density measurements 2. Total body water – hydrometry 3. Ultrasound 4. Magnetic resonance imaging 5. Computerized tomography 6. Total body potassium These laboratory methods are reasonably accurate but they are expensive, cumbersome and require highly trained technicians. Conclusion - results of estimation of body composition should be interpreted cautiously

Answer 34

Changes associated with aging in western society: • increased fat mass (creeping obesity) • decreased muscle mass - sarcopenia • decreased bone mass These changes can be slowed down by a regular exercise program and proper dietary habits. Recent evidence indicates that skeletal fragility in elderly women is related to failure to obtain an optimal level of bone mass during childhood. sarcopenia: banishing flesh, the older you get, the less flesh you have

Answer 35

Type II diabetes mellitus Hypertension Coronary artery disease Stroke Sleep apnea: stop breathing for 20-40 secs Gallbladder disease Osteoarthritis of the weight-bearing joints Gout Reduced fertility Impaired obstetric performance Reduced physical agility

Answer 36

Fluid-electrolyte imbalances Osteoporosis Bone fractures Muscle wasting Cardiac arrythmias and sudden death Peripheral edema Renal disorders Reproductive disorders

Answer 37

"the progressive development of a living being or part of an organism from its earliest stage to maturity, including the attendant increases in size". maturity: how close we are to the endpoint

Answer 38

Growth involves a series of changes not just the addition of material to achieve an increase in size. These changes involve a differentiation of various parts of the body to perform different functions. -Not all parts of the human body grow at the same rate, nor do they all stop growing simultaneously. -The body does not retain the same proportions throughout growth and the relative weights of given tissues and organs do not remain constant. -the brain at birth is about 24 % of its adult weight, whereas the neonatal body is only about 6 % of its adult weight. -Extremely rapid growth of the brain continues, so that by the time the child is five years old the brain has reached 90 % of its adult weight, whereas its body weight is only 25 % of its eventual adult weight. -The reproductive organs, on the other hand, remain at less than 10 % of their final weight until the onset of puberty.

Answer 39

1. Neonatal Period - extends from birth to the end of four weeks. 2. Infancy - extends from the end of the neonatal period at four weeks until two years of age. Infancy is characterized by tremendous growth, increased coordination, and mental development. 3. Childhood - the period of growth and development extending from infancy to adolescence, at which time puberty begins. The chronological duration of childhood varies because puberty begins at different ages for different people. Childhood years are a period of relatively steady growth until preadolescence when there is a growth spurt. 4. Adolescence - the period of growth and development between childhood and adulthood. It begins around the age of nine in girls and the age of eleven years in boys. The end of adolescence is approximately 17-18 years, but it is not clearly delineated. 5. Adulthood - the period of life beyond adolescence. An adult has reached maximum physical stature as determined by genetic, nutritional, and environmental factors.

Answer 40

Distance curve - measurements taken at intervals are plotted against time to produce a graph of progress. Velocity curve - increments in growth are plotted against time to show the variation in the rate of growth with time. Longitudinal data - growth curve is derived from a single individual or from repeated measurements on the same group of individuals over a period of many years. Cross-sectional data - measurements are made of several children in each age group, and these are then combined to form a cross-sectional picture of the various age groups in the community at the time of the investigation.

Answer 41

Growth is a regular process, it doesn't proceed by stops and starts. From birth to maturity, the most important difference between boys and girls is in the rate of maturity. Girls grow up faster than boys - they reach 50 percent of their adult height at an earlier age (1.75 vs. 2.0 years), enter puberty earlier, and cease growing earlier. Half way through the foetal period, the skeleton is already three weeks more advanced in girls; at birth, the difference is four to six weeks of maturation; at puberty, the difference is two years.

Answer 42

there is little difference between the average height of boys and girls. Because the spurt begins earlier in girls, there is an age (approximately 9-10 years) at which girls become taller and heavier than boys of the same age. This balance is redressed by age 14. The mean growth takeoff age (i.e., the onset of growth acceleration) in children in North America growing at an average rate is approximately 12 ± 1.5 years in boys and 10 ± 1 year in girls. The age at takeoff correlates highly with pubertal stage. During the spurt, boys add approximately 20 cm to their height mostly because of growth of the trunk while girls gain about 16 cm in height.

Answer 43

Peak height velocity in boys – 14 years Peak height velocity in girls – 12 years The standard deviation for age at peak height velocity is slightly less than one year. The peak height velocity is highest in early-maturing children and lowest in late-maturing children. Since the peak height velocity may occur as much as two years earlier or later than the average within each sex, a six year difference in the event between an early maturing girl and a late maturing boy is quite possible.

Answer 44

The conclusion of the growth spurt is followed by a rapid slowing of growth. In USA cross-sectional studies, boys with a mean takeoff age of 12 years reached their final heights by 17-18 years of age, and girls with a mean takeoff age of 10 years reached their final heights by 14-15 years of age. However, there is a wide variation around these means - plus or minus two years. Boys end up being taller than girls because they have two more years of growth before the growth spurt. During these two extra years of prepubertal growth in boys, the legs are growing relatively faster than the trunk. Thus the average male has relatively longer legs than the average female. Height can also be sued as a proxy for living standards through decades or centuries. As living standards have improved so has the average height of the population. Usually true unless there is a confounding factor of a higher death rate amongst small babies.

Answer 45

Weight of ovum ---> birth - 3 X 109 Birth ---> maturity (20 years) - 20 X Birth ---> 2 years - 4 X, then steady increase of 2 - 3 kg per year until growth spurt. During the growth spurt, boys may add 20 kg to their weight, and girls 16 kg. The peak velocity for the spurt in weight lags behind the peak velocity for height by about 3 months - child shoots up and fills out later.

Answer 46

a condition of the bones where they become thin and brittle due to decreased mineral content, which makes them susceptible to fracture.

Answer 47

For all bone sites in both boys and girls, peak velocity in bone mineral content occurs approximately one year after peak height velocity. This suggests that there could be a transient period of relatively long bone weakening during the adolescent growth spurt, resulting in an increased fracture risk following peak height velocity. The need for calcium during peak linear growth is substantial. An adequate level of vitamin D in the body is also important – effects of sunshine and diet. Vitamin D deficiency is not uncommon among children and adolescents, particularly during the dark seasons of the year. As much bone mineral will be laid down during the four adolescent years surrounding peak height velocity as most people lose during all of adult life. Peak bone mineral density of the lumbar spine and hip is achieved around the age of 20 years.

Answer 48

More than 90 % of adult bone mineral is present by the end of skeletal maturation and any gains in bone mass after growth has ceased are minimal. Fifty percent of the variability in bone mass in the elderly can be accounted for by peak skeletal mass attained during the years of growth and maturation. Therefore, the prevention of osteoporosis depends not only on reducing the rate of bone loss during adult life, but also on the maximization of bone mineral accrual during the growing years.

Answer 49

The relation between one part and another of the growing body is not a consistent one, but changes with age.

Answer 50

Large head - ratio of head height to total height equals 1:4 in the infant, 1:7.5 in the adult. Lower limbs are much less well developed at birth than upper limbs - ratio of leg length to total height equals 1:3 in infant, 1:2 in adult.

Answer 51

At all ages the dimensions of the head are in advance of those of the trunk, and at all ages more peripheral parts of the limbs are in advance of the more central parts - foot --> calf--> thigh. The bones of the face grow faster than those of the cranial vault - "at adolescence the face emerges from underneath the skull". In the later stages of the adolescent spurt, there is laterality of growth rather than linearity.

Answer 52

refers to the period at which the testes, prostate gland, and seminal vesicles or the breasts, uterus and vagina, suddenly enlarge. This is the time of greatest sex differentiation since the early intra-uterine months – sexual dimorphism. There are changes in reproductive organs and secondary sex characteristics, in body size and shape, and in relative proportions of muscle, fat, and bone.

Answer 53

Studies conducted in the USA have indicated that there are no differences in various stages of pubertal development in African American boys and white boys. However, these studies have shown a significant difference between African American girls and white girls at every stage of development. The average age of occurrence in North America is 12.8 - 13.0 years in white girls and 12.2 to 12.5 years in African American girls. There is a standard deviation of plus or minus one year. The 95 percent range is 11.0 - 15.0 years. All girls start to menstruate when the height velocity is falling. The development of mature ova follows menarche by as much as two years; therefore puberty is not complete in females until sexual maturity has been attained. A research study reported in the April 1997 issue of “Pediatrics” indicated that girls in the United States mature sexually earlier than previously expected

Answer 54

refers to the onset of menstruation. It occurs relatively late in puberty.

Answer 55

It is important to be able to assess how far an individual child has progressed towards maturity. The chronological age of a child is an unreliable guide since children mature at very different rates and measurements of height and weight are only partially useful.

Answer 56

During growth, every bone goes through a series of changes which can be recorded radiographically. The times of appearance of primary and secondary centers of ossification can be observed and the progressive enlargement of the ossified portion of an epiphysis can be followed in detail. The radiological examination allows one to determine how far the skeleton of a child has progressed toward the adult condition. The wrist and hand are most commonly used for this purpose because, in this region, there is a large number of centers of ossification. At every chronological age up to full maturity, the radiological age of girls is in advance of that of boys by a factor of about 20 percent or more.

Answer 57

The deciduous dentition erupts from six months to two years of age and can be used during that period. The permanent dentition provides a measure from six to 13 years of age. Skeletal maturity and dental maturity are not closely related in the individual.

Answer 58

The timing of the peak height velocity and the peak weight velocity are useful maturity indicators.

Answer 59

The secondary sex characteristics can be used as a method of rating maturational development. Ratings can be made of stages in pubic hair development, stages in breast development, and stages of genital development. These indicators have limited applicability over the growth span, in contrast to skeletal maturation, which can be monitored from infancy into young adulthood. The “Tanner” stages of sexual maturity are used as the universal standard for classifying sexual maturity. The age at which menarche occurs is an important indicator of maturation status in females. Menarche is more closely related to radiological age (12 - 14.5 years) than to chronological age (10 - 16 years).

Answer 60

In spite of the large size of the central nervous system at birth, much of it is incompletely functional and requires considerable time to develop to the stage at which it can be fully utilized. Girls are ahead of boys throughout the phase of motor and sensory development - on the average, girls learn to walk earlier, control their bladders earlier, and are ahead in the use and understanding of speech. They are also first in the development of skills which need fine movements and coordination, such as tying bows.

Answer 61

Five types of skeletal development have been recognized. (1) Average children (2) Early maturers - tall in childhood but not as adults (3) Early maturers and genetically tall (4) Late maturers - small in childhood, average as adults (5) Late maturers and genetically short

Answer 62

There is good evidence that, in European and North American school systems, children who are physically advanced towards maturity score, on average, slightly higher on most tests of mental ability than children of the same age who are less physically mature. It is very likely that mental and psychological developments are much more closely related with radiological age than with chronological age.

Answer 63

on average, tend to mature earlier than others and have an early adolescent growth spurt. Late maturing boys are greatly handicapped in competition with early maturing boys. Late maturing boys may be deselected from age-class sports too early, while early maturing boys may develop unrealistic expectations and have difficulty adjusting to their loss of sports advantage when their late maturing peers catch up.

Answer 64

Genetic Control Nutrition Secular/Historical Trends Season and Climate Differences Between Races Saltation and Stasis Catch-up Growth

Answer 65

Both genetic and environmental factors influence growth, and the progress of any given child is the result of a complex interaction of many different factors. Studies of twins have shown that body shape and size, deposition of fat, and patterns of growth are all more closely related to nature than to nurture. Heredity affects not only the end result of growth, but also the rate of progress toward it.

Answer 66

Malnutrition delays growth. Children subjected to an episode of acute starvation recover more or less completely provided that the adverse conditions are not too severe and do not last too long. Adult size is affected by a less severe level of under-nutrition than adult body proportion (i.e., leg length versus trunk length, etc.)

Answer 67

Paleontologists etc have dug up enough bones on this planet to estimate the size of humans over time. About 9,000 years ago human height decreased. This is attributed to a nutritional change to a more grain-based diet. Some vitamins and mineral important for growth would be substantially reduced. Between 1880 and 1950, the average height of American and West European children between the ages of five and seven years increased by more than 1/2 inch per decade for a total of more than four inches. Children are now growing faster and stopping growing earlier. There has been an upward trend in adult height of one centimeter per decade since 1880. In Western European countries, the average age of menarche decreased from 16 years in 1880 to 13 years in 1960.

Answer 68

There is quite a close correlation between the linearity of people as adults and the average annual temperature of the area where they live or from which they migrated in historical times. The long limbs of the Africans enable them to lose more heat per unit volume than the European, and the thick-set body and short limbs of the northern Asiatics are similarly adaptive in Arctic regions. Contrary to popular opinion, climate has, at most, a very minor effect on age of menarche. People living in tropical countries frequently have a late menarche because their nutritional status is low. Studies done on West European children indicate that season of the year may exert a considerable influence on velocity of growth. The children grew faster in height in spring and summer than in autumn and winter. Weight gain was faster in the autumn than in the spring.

Answer 69

Populations differ in their average adult size and their tempo of growth as well as their shape. Consider three population groups - European, African, and Asiatic Height - Asiatic boys and girls are shorter Body proportions - compared to Europeans, Chinese have relatively longer trunks and shorter legs. Africans are the opposite. Compared to Europeans and Asiatics, Africans have slimmer hips for a given shoulder width. Africans have more muscle and heavier bones per unit weight, at least in males, together with less fat on the limbs in proportion to fat on the trunk. Tempo of growth - well off Asiatic and African children are ahead of European children in skeletal age and dental maturity.

Answer 70

Growth occurs in a series of rapid rates interspersed by long periods of stasis. In essence, this is a synchronous display of cartilaginous tissue going through a cell, or rather, a tissue cycle.

Answer 71

Catch-up growth is a remarkable phenomenon in which significantly reduced growth perturbations can be completely alleviated by proper corrective action such correcting diet or hormone deficiencies. This demonstrate the underlying genetic control of human height.

Answer 72

1. Cardiorespiratory endurance - aerobic power 2. Strength 3. Muscular Endurance 4. Flexibility 5. Body Composition

Answer 73

1. To assess the status of individuals entering a program. 2. To aid in prescribing or limiting activity of certain individuals. 3. To evaluate an individual's progress. 4. To increase individual motivation for entering and adhering to an exercise program. 5. To evaluate the success of a program in achieving its objectives

Answer 74

The subject's human rights are respected - Informed Consent Form. The subject is given a thorough explanation of the purpose of the test, possible risks, benefits, etc.

Answer 75

Measurement error makes the observed value of a measure differ from the true value. 1. Validity 2. Reliability 3. Objectivity 4. Accuracy 5. Norms 6. Economy

Answer 76

a valid test is one that measures effectively what it is supposed to measure. Compare the test results to a criterion measure or reference standard - there should be a high relationship

Answer 77

are the results consistent and reproducible? A highly reliable test yields the same or approximately the same scores when administered twice to the same individuals, provided conditions and subjects are essentially the same. Error – the deviation of a measurement, observation, or calculation from the truth. Random errors influence the results in a random (statistically unpredictable) manner. They cause the results to spread in both directions (positive and negative) about the true value. If a result is not repeatable --> random errors --> repeat the measurement several times and take the mean There will always be a certain amount of random error - due to a combination technical error and biological variation in performance. Test administration should be rigidly controlled - standard instructions to the subjects, standard practice or warm-up procedures, standard order of test items and recovery times between items, standard environmental temperature and humidity, and standard equipment and equipment calibration procedures. Skills that require a high proficiency of coordination and reaction should be tested before any tests that may cause fatigue and decrease performance.

Answer 78

the level to which multiple testers agree on the scoring of tests. To optimize objectivity, it is best to use trained testers, a predetermined scoring system, and if possible, one designated tester.

Answer 79

A measure of how close a result is to the “true” value. The accuracy with which things are measured, or with which differences are perceived, depends first upon the precision of the measuring instruments. All measuring instruments have their limitations. Systematic errors - errors that systematically shift the measurements in one direction away from the true value. They can be caused by instrumentation errors or by the use of incorrect measurement techniques. Gain versus offset errors Systematic errors caused by a measuring instrument can be estimated by comparison with a more accurate and reliable instrument - calibration of instruments.

Answer 80

allow a relative rating or classification of the subject's performance. They describe a person’s position in a population. If the only information available about a subject's test performance is the raw score, interpreting it meaningfully can be difficult. A norm describes a subject in relation to a large number of people who have taken the test. Norm charts should be evaluated to determine their quality. The following questions should be asked: a) Were the sampling procedures for the construction of the norms based on a wide distribution of the population? b) Was a large sample size used to construct the norms? c) Are the norms being used for the specific groups for which they were prepared? Percentile – a point or a position on a theoretical scale of 100 divisions such that a certain fraction of the population of raw scores lies at or below that point. Median – the 50th percentile, the score that divides a distribution so that 50% of the scores are above this point and 50% fall below.

Answer 81

consider two factors: a) money costs and b) time required of subjects and testers Other things being reasonably equal (validity, reliability, accuracy), choose a test that meets your objectives and requires little in money and time. Laboratory tests – typically require specialized equipment and specialized training for the test administrator. They are usually administered to only one person at a time. Field tests – require no expensive equipment and little, if any, specialized training. These tests can be administered to a group of individuals at the same time, and they are usually less precise than laboratory tests.

Answer 82

are the only cells in the body that have the property of contractility, which allows them to shorten and develop tension. - 3 types

Answer 83

attaches to and moves the skeleton. The contractile molecules are very organized giving skeletal muscle a striated pattern, hence the name, “striated muscle”. It is under voluntary control. Skeletal muscle comprises about 36 % of the total body weight in women and 42 % in men. 75 percent of skeletal muscle is water, 20 % is protein, and the remainder consists of inorganic salts, pigments, fats, and carbohydrates.

Answer 84

found in the walls of hollow organs and blood vessels. The contractile molecules are not aligned in a set pattern like skeletal muscle, hence the name smooth muscle. This muscle is under involuntary control.

Answer 85

the contractile tissue of the heart wall. This muscle has characteristics of both smooth muscle and skeletal muscle. The contractile molecules are organized very much like skeletal muscle. Like smooth muscle, it is also under involuntary control.

Answer 86

1. Shape - deltoid (triangular), trapezius, rhomboid, latissimus (wide) 2. Action - various muscle names include the terms flexor, extensor, adductor, or pronator. 3. Location - tibialis anterior, intercostals, pectoralis major 4. Divisions - triceps brachii, quadriceps femoris 5. Size relations - gluteus maximus, gluteus medius, gluteus minimus. Several names include the terms "brevis" (short), and "longus" (long). 6. Direction of fibers - transversus (across), rectus (straight)

Answer 87

A fascicle is a bundle of muscle fibres that are encased by perimysium. Fasciculi may run parallel to long axis of muscle (great range of motion, little strength) or insert diagonally into a tendon running the length of the muscle (small range of motion, greater strength). 1. Unipennate - all fasciculi insert on one side of a tendon - semimembranosus 2. Bipennate - fasciculi insert on both sides of tendon - rectus femoris 3. Multipennate - convergence of several tendons - deltoid 4. Longitudinal (strap) - fasciculi run parallel to the long axis of the muscle - sartorius, rectus abdominus 5. Radiate - fibers fan out from a single attachment - pectoralis major

Answer 88

Most movements require the cooperative action of several muscles functioning as a group. 1. Prime mover - a muscle whose contraction is primarily responsible for a particular movement. Most movements are the result of the contraction of more than one muscle, and frequently a single muscle contributes to the production of two or more movements. 2. Antagonist - muscles that oppose one another upon contraction - biceps and triceps. Antagonists are located on opposite sides of a joint. 3. Fixators/stabilizers - muscles that immobilize a bone or joint near the origin of the prime mover so that the prime mover can act more efficiently. Note that a few muscles in our body have no real function. The plantaris muscle which flexes all our toes is exceptionally functional for primates but no longer even reaches our toes and is actually absent in about 10 % of the population.

Answer 89

Tendons are extensions of connective tissue membranes beyond the end of the muscle. Origin - less movable end of a muscle, usually proximal. Insertion - more movable end of a muscle, usually distal. Belly - widest portion of a muscle, between its origin and insertion. Not all muscles insert on bone. Most of the muscles controlling facial expression originate from bone and insert in the skin.

Answer 90

The three layers of connective tissue, endomysium, perimysium, and epimysium, surrounding muscle fibers, bundles of muscle fibers (fasciculi), and whole muscle, respectively, serve in part to maintain intramuscular pressure thereby augmenting force production. Tendons are extensions of connective tissue membranes beyond the end of the muscle. Tendons transmit the force of contractile tissue to bone. Tendons are much stronger than muscle and as such can receive force from a large number of muscle fibers (with a much larger total cross-sectional area than the tendon) and insert on to a small area of a bone such as a tuberosity.

Answer 91

Because muscle tissue can increase its metabolic rate 100x, it has an abundant blood supply. On average, there are about 3-4 capillaries surrounding each muscle fiber of a sedentary person. Training can induce capillary angiogenesis, resulting in up to 7 capillaries per muscle fiber. Muscles require a good supply of blood for continued force generation. The problem is when muscle force increases, so does intramuscular pressure. The increase in intramuscular pressure can exceed that of blood pressure thus restricting blood flow within the muscle. In general, this can start to occur at about 15-20 % of maximum muscle force and completely halt blood flow at about 50 % of maximum force.

Answer 92

A muscle cell is a muscle fiber. Within each muscle cell/fiber are many myofibrils. Each myofibril consist of a large array of contractile proteins arranged repeatedly in series. This gives skeletal muscle its striated pattern of light and dark areas or bands. Each repeated array of contractile proteins is called a sarcomere. The two major contractile proteins of the sarcomere are actin (thin filament) and myosin (thick filament). Myosin has cross-bridges extending from its thick central core. The most prominent theory of muscle contraction is the sliding filament theory. This theory suggests that, when the muscle is activated, the protruding cross-bridges on myosin attach to actin and, with the aid of ATP, the cross-bridge microstructure can “rotate” thus causing the thin actin filament to “slide” over myosin. This causes the sarcomere to shorten. maximal shortening is about 20%

Answer 93

-A motor neuron in the spinal cord is stimulated -A nerve action potential travels to the muscle -Muscle cells are stimulated -A muscle action potential moves across the muscle membrane and down into the t-tubules -Sarcoplasmic reticulum (SR) is stimulated to release calcium -Calcium binds to troponin Actin binding sites are exposed -Myosin heads attached to the actin binding sites forming a cross bridge (XB) -Myosin heads ‘flip’ and myosin dissociates from actin -Myosin is recharged with ATP -Binding and sliding continues -With no more nerve stimulation, calcium is pumped back into the SR -Actin binding sites get covered again by tropomyosin -No calcium equals no tension

Answer 94

Activation of a muscle fiber can, in the extreme, produce either maximum force or maximum velocity. In between these extremes, a muscle fiber creates a combination of force and movement. Force related to…. cross bridges Speed related to …. slow speed, more cross-bridges fast speed, skip cross-bridges

Answer 95

A motor unit is the functional unit of a muscle. It consists of a motor neuron (alpha) and all the muscle fibers that motor neuron innervates. The cell body of a motor neuron is located in the spinal cord. The axon of that motor neuron extends from the spinal cord to the target muscle which may be a few millimeters away or a few feet away. When the axon is close to the muscle it separates many times (bifurcates) to innervate all the muscle fibers of that particular motor unit. For an average motor unit the motor neuron will innervate about 200 muscles fibers. The range is from 2-3 muscle fibers per motor unit for muscles capable of very fine movements to 2000 fibers per motor unit for large muscles that perform only gross movements. If the cell body of the motor neuron receives a strong enough stimulus, an action potential is generated. This action potential travels along the axon and all its bifurcations to stimulate each and every muscle fiber in that particular motor unit. This is known as the all-or-none law.

Answer 96

Motor units can be classified in two ways on the basis of speed of contraction (slow twitch & fast twitch), and in three ways on the basis of metabolic characteristics: Slow twitch oxidative (SO) – also called “type I” Fast twitch oxidative-glycolytic (FOG) – also called “type IIa” Fast twitch glycolytic (FG) – also called “type IIb”

Answer 97

Men, women, and children generally have 45 to 55 % slow twitch fibers in their arm and leg muscles. However, there can be considerable variation in fiber type distribution from muscle to muscle and from person to person. All of the muscle fibers in a given motor unit will have identical contractile and metabolic properties. Endurance athletes have higher than average proportions of slow twitch muscle fibers in the muscles used in their sport, while power athletes have high proportions of fast twitch muscle fibers. Slow twitch fibers and fast twitch fibers can’t be inter-converted by physical training. However, FOG and FG fibers can be inter-converted by physical training. Current research indicates that genetic factors largely determine a person’s predominant muscle fiber distribution.

Answer 98

1. Multiple Motor Unit Summation. A large muscle may contain up to 2,000 motor units. A skeletal muscle can increase force production by activating more motor units. A low force requires the activation of a small number of motor units while a higher force requirement progressively enlists more motor units. 2. Frequency or Wave Summation. If a single action potential travels down a motor neuron axon, the motor unit response is a twitch. If many action potentials travel down the axon at a rate faster than the twitch response time of the motor unit, then the mechanical force response will summate. At high motor neuron firing rates (i.e., many action potentials in a short period of time) this effect can generate on average about 5x the force of a single twitch. When all motor units are activated, and they are all activated at a high firing rate, then the muscle is maximally activated.

Answer 99

there is a recruitment order of motor units as exercise intensity increases. As the muscle force requirement increases, motor units with progressively larger axons are recruited. Slow twitch motor units with the lowest activation threshold are selectively recruited during light to moderate effort. More rapid, powerful movements progressively activate FOG motor units and then FG motor units.

Answer 100

An isolated muscle can exert its maximal force or tension while in a resting stretched position. As the muscle shortens, less tension can be exerted. When a muscle is stretched or shortened, the length of each individual sarcomere also increases or decreases, respectively. Within the range of sarcomere lengths there is an optimal length at which provides for the greatest possible number of cross-bridge formations. Longer or shorter than this optimal length, the number of cross-bridge formations is reduced and thus active force production is reduced. Muscles must be stretched from their resting length for most effective action. Example - flexing the knee, hip, and ankle joints before jumping. In a movement such as vertical jumping, preparatory counter movement shifts the force-velocity curve to the right, thus causing the leg extensor muscles to exert much higher forces at any angular velocity of the knee in the concentric phase. The enhancement of performance in this "stretch-shortening" cycle can be attributed to restitution of elastic energy and stretch reflex potentiation of muscle.

Answer 101

When maximally activated, the faster a muscle shortens the less force it produces. When the velocity of shortening is zero, this is defined as an isometric contraction (i.e., no change in muscle length). If the velocity is negative, then the muscle is lengthening when it is activated. This is an eccentric contraction. An example of an eccentric contraction is when you slowly lower the barbell after doing a biceps curl. You are still using your biceps, but your muscle is lengthening. In this condition it is possible for the biceps to generate more force than at the opposite speed while shortening. This eccentric type contraction is what is targeted when performing the training technique of plyometrics. Remember, the curve defining the force-velocity relation is based on maximal activation. The vast majority of muscle activations we use are of the submaximal variety and are located well underneath the maximum curve. Power is not an independent factor influencing force, rather power is the product of force times velocity. In many athletic endeavours, it is power that is the most important variable determining success. The graph of the relation of power with velocity shaped like an upside down 'U', hence the name the "inverted U hypothesis" is sometimes used when describing this relation (see Fig. 11-5 in Lab Manual). This inverted U type relation occurs because on the left of the graph, when velocity is zero, power must be zero. As with the force-velocity curve, most of our muscle activations are well below the maximum curve power is force times velocity The peak torque generated by a muscle decreases with increasing velocities of movement. Maximum power output occurs at approximately one half of maximum velocity and one third of maximum concentric force.

Answer 102

In the intact human body, the muscles act on the bones about the joints to form a lever system. When a muscle is pulling at an angle of 90 degrees to a bone, all of the muscle contractile force is acting to rotate the bone around the joint. At angles greater than 90 degrees, the magnitude of the rotational component of the muscle pull force decreases while the magnitude of the stabilizing component of the force increases.

Answer 103

1. Speed of shortening. 2. The initial length of the muscle fibers. 3. The angle of pull of the muscle on the bony skeleton.

Answer 104

the greatest amount of force that muscles can produce in a single maximal effort.

Answer 105

work per unit time = force X velocity. Power involves strength and speed.

Answer 106

1. dynamic (isotonic) contraction -concentric contraction -eccentric contraction 2. isometric contraction 3. isokinetic contraction 4. eccentric loading 5. plyometric loading

Answer 107

the bony levers move through a range of motion when the appropriate muscles perform work. Concentric contraction - the muscle shortens with varying tension as it lifts a constant load. Eccentric contraction - the external resistance exceeds the muscle force and the muscle lengthens while developing force. Eccentric contractions are usually used in resisting gravity.

Answer 108

static contraction. Tension is developed but there is no change in the angle of the joint or the length of the muscle.

Answer 109

the muscle is shortened at a constant velocity determined by instrumentation which allows a person to exert maximal force throughout the full range of motion.

Answer 110

Any exercise that can be performed concentrically can also be performed eccentrically. For example, in the bench press exercise pushing the bar from the chest to the finish or arms extended position involves a concentric contraction of the pectorals major, anterior deltoid, and triceps muscles. Lowering the bar back to the chest involves an eccentric contraction of the same muscle groups. In eccentric loading for the bench press exercise one would start with a heavy weight in the arms extended position and then slowly lower the bar to the chest. A partner would then help to get the bar up again. Several studies have shown that this is an effective means of gaining strength, although it is not superior to other isotonic techniques. One drawback of eccentric training is that it creates more muscle soreness (delayed onset muscular soreness; DOMS) than other methods, especially for anyone not used to the movement. Eccentric loading is not widely practiced by strength athletes except as an adjunct to other training methods.

Answer 111

In plyometric loading the muscles are loaded suddenly and forced to strength before they can contract and elicit movement. Plyometric drills include bounds, hops, jumps, leaps, swings, twists, and other movements. Plyometrics is one of the best ways to develop explosive power for sports. It is a very vigorous form of exercise. In order to avoid injury to muscles (DOMS), tendons and joints, it is very important to establish a good base level of strength before using plyometric training methods.

Answer 112

The ability to carry out daily tasks with vigour and alertness, without undue fatigue, and with ample energy to enjoy leisure time pursuits and to meet unforeseen emergencies.

Answer 113

1. one repetition maximum 2. dynamometer techniques 3. computer-assisted, isokinetic methods

Answer 114

maximum amount of weight lifted once. Use free weights or machines that allow dynamic muscle contractions - Universal Gym, etc. Nautilus Machines - accommodating resistance devices - leverage characteristics change as the joint goes through a range of motion so that the muscle is stressed more at more optimal joint angles.

Answer 115

a strength testing dynamometer usually consists of a spring of some type which is deformed a certain amount when a specific force is applied to it (e.g., - hand grip dynamometer). - measures isometric strength - relatively inexpensive, high reliability if body position is carefully standardized for each trial of the test

Answer 116

equipment such as Cybex, Biodex, KIN/COM, etc. - isokinetic machine, but many of these machines can also test strength in isometric, concentric, and eccentric modes - has a microcomputer which can be programmed at any initial and final force, angle, velocity, or number of repetitions. - measure peak torque using a force transducer and joint angle using an electrogoniometer. - extensive manipulations can be performed on collected data using computer software - accurate and reliable, but expensive

Answer 117

In addition to validity, reliability, etc., 1. Standardized instructions should be given prior to testing. 2. If a warmup is given, it should be of uniform duration and intensity 3. Ensure that the angle of measurement on the limb or test device is consistent among subjects 4. Consider individual differences in body size and proportion when evaluating strength scores between individuals and groups. 5. Test and training mode specificity are important for optimal expression of true strength gains. Training using one mode of muscle activity (concentric, eccentric, isometric, isokinetic) should typically be assessed within an identical type of muscle activity within a strength testing profile. 6. Safety is an important consideration when performing strength evaluations. Ensure that all equipment is in proper working order and that standard weight room safety procedures are being followed. 7. Test administrators should be well trained and have a thorough understanding of all testing procedures and protocols.

Answer 118

1. Muscle Cross Sectional Area 2. Body Size 3. Muscle Fiber Composition 4. Mechanical Factors 5. Sex and Age

Answer 119

there is a strong positive relationship between muscle CSA and strength. Muscles increase in strength by increasing their size and by enhancing the recruitment and firing rates of their motor units. Hypertrophy - an increase in size of a cell such as a muscle fiber Hyperplasia - an increase in number of cells such as muscle fibers. Current research indicates that muscle fiber hypertrophy accounts for most, if not all, of the increase in muscle cross-sectional area due to an overload training program. There is evidence that muscle fiber hyperplasia occurs in animals, but there is presently no direct evidence that it occurs in humans.

Answer 120

there is a positive correlation between body size or mass and absolute strength. There is a negative correlation between body mass and the strength/mass ratio. The strength to mass ratio directly reflects an athlete’s ability to accelerate his or her body. All else being equal, smaller athletes are stronger pound for pound than larger athletes. In comparing performances of Olympic weight-lifters in different weight categories, the most widely used formula is to divide the weight lifted by body weight to the 2/3 power. Large athletes dominate sport events which require a high level of absolute strength (e.g., throwing events in track and field) while smaller athletes dominate sport events which require a high strength/body mass ratio (e.g., gymnastics).

Answer 121

for a given size of muscle, there is a positive correlation between percentage of fast twitch fibers and strength. AND an increase strength with training and %FT fibres.

Answer 122

the force exerted by a muscle is affected by: a) the initial length of the muscle fibers b) the angle of pull of the muscle on the bony skeleton c) the speed of shortening if you let go of an elastic band with weight on or no weight there will be a difference in velocity

Answer 123

after age 16, the average female is about 2/3 as strong as the average male when the measure of strength is the absolute amount of force exerted or weight lifted. Prior to puberty the strength of boys is only slightly greater than the strength of girls.

Answer 124

• Muscle strength progressively improves as children age and mature, principally as a result of increasing muscle size. • Hormonal influences at puberty (testosterone) are responsible for the dramatic increase in muscle bulk and strength in males. During this time period the increase in muscle mass in both sexes is due to hypertrophy of individual muscle fibers and not hyperplasia. • Muscle strength can be improved by resistance training before puberty in both boys and girls. These changes occur without significant increases in muscle size. • Consider chronological age versus biological age when designing individualized weight training programs for children • During the time period surrounding peak height velocity (age ~12 in girls and age ~14 in boys), young athletes may be at increased risk for injury.

Answer 125

greater in the arms and shoulders than in the legs. On average, the female's upper body is 50 % to 60 % as strong as the male's upper body and the female's lower body is 70 % to 80 % as strong as the male's lower body. It is important to note here that we are talking about the "average" male and the "average" female. However, individuals are not average and the differences between two individuals of the same sex are often greater than differences between statistical averages of each of the sexes.

Answer 126

• The average male is physically larger (height and weight) than the average female. • Differences in body composition - the average male has more muscle and less fat due to the male sex hormone, testosterone, which stimulates muscle growth. Because most human muscles can produce approximately 16 to 30 newtons of force per square centimeter cross-sectional area, larger muscles are stronger muscles. • Body proportion differences - during adolescence, the skeletal proportions change: boy's shoulders broaden relative to their hips, and girl's hips broaden relative to their waists and shoulders. The broader shoulders of the adult male allow more muscle to be packed onto the skeletal frame and create a mechanical advantage for muscles acting on the shoulder. • Cultural factors - less emphasis on strength activities for females, although weight training has become much more popular and socially acceptable for females in the last ten years.

Answer 127

There is no qualitative difference between male and female muscle. You cannot distinguish male muscle from female muscle under a microscope. Female muscle tissue does not differ, unit for unit, in potential force output from male muscle tissue. This indicates that the training potential and methods of training for men and women should be similar. After strength training on the same routine, men have greater absolute increases in both strength and muscle hypertrophy than women. However, women achieve similar percentage increases in strength as men. Women display less muscle hypertrophy since they lack testosterone. Recent research has revealed that men and women of all ages can increase their muscle size and strength as a result of progressive strength training. There is a great deal of variability in the responsiveness of muscles to strength training within sexes and age groups - individual differences. Maximum strength of men and women is generally achieved between the ages of 20 and 30 years, at the time when muscle cross sectional area is usually the greatest. Thereafter, there is a progressive decrease in strength for most muscle groups due primarily to a reduced muscle mass that is brought about by a decrease in the total number of muscle fibers in a given muscle and a decrease in individual fiber size. These changes are more pronounced in the fast-twitch fibers. These changes in muscle volume are due to a combination of decreased physical activity patterns and aging.

Answer 128

Recently, muscle rehabilitation programs for well, older populations have shown significant increases in muscle strength, muscle volume, and other parameters of muscle structure and function. Studies have documented that, given an adequate training stimulus, older men and women show similar or greater percentage strength gains compared to young individuals after a properly designed strength training program. For the older person (age 65-85 years), muscle strength is a major component of successful performance in almost every activity of daily living. It is vital to the maintenance of upright posture, walking, going up and down stairs, and the accomplishment of simple tasks such as eating and dressing.

Answer 129

• STRENGTH PROVIDES A FOUNDATION FOR OTHER COMPONENTS OF PHYSICAL FITNESS SUCH AS CR CAPACITY AND MUSCULAR ENDURANCE • SLOW DOWN THE MUSCLE LOSS THAT NORMALLY ACCOMPANIES THE AGING PROCESS --> INCREASE FUNCTIONAL MOBILITY SO THAT DAILY ACTIVITIES ARE MADE BOTH POSSIBLE AND EASIER • INCREASE THE SIZE AND STRENGTH OF MUSCLE FIBERS RESULTING IN A GREATER PHYSICAL CAPACITY TO PERFORM WORK • INCREASED TENDON, LIGAMENT AND BONE TENSILE STRENGTH • STRONGER MUSCLES BETTER PROTECT THE JOINTS THAT THEY CROSS • IMPROVED PHYSICAL APPEARANCE • BETTER TONE OF THE MUSCLES OF THE TRUNK HELPS TO PREVENT COMMON POSTURAL PROBLEMS • STRONGER MUSCLES ARE LESS LIKELY TO BE STRAINED AND INJURED • IMPROVEMENTS IN SELF-CONCEPT AND SELF-ESTEEM FOR BOTH ATHLETIC AND PATIENT POPULATIONS

Answer 130

the application of mechanical laws to living structures, specifically to the locomotor system of the human body.

Answer 131

• Improvement of sports skill techniques • Design of sports equipment • Prevention of injuries • Clinical analysis of movement pathologies • Design of prostheses • Design of rehabilitation devices and video game movements

Answer 132

a non-numerical description of a movement based on direct observation. Conducted primarily by teachers and coaches.

Answer 133

a movement is analyzed numerically based on measurements from data collected during the performance of the movement. Conducted by researchers.

Answer 134

first class lever second class lever third class: We are mostly speed levers. most muscles are third class Mass – the quantity of matter contained in an object. Units = kilograms (kg) Force = mass X acceleration. Units = newtons (N) 1 N = (1 kg) (1 m/s2) Weight – the amount of gravitational force exerted on a body Weight = mass X acceleration of gravity = mag Acceleration of gravity = 9.81 m/s2 Units of weight – newtons If a person has a mass of 80 kg, their weight = (80 kg) (9.81 m/s2) = 785 N The moon has 1/6 the gravity of earth so the above person would weigh 131 N. Same mass, different weight. We sometimes use a force unit of convenience called a kilopond (kp). A kilopond is equal to 9.81 N, hence if you have a mass of 80 kg, you weigh 80 kp.

Answer 135

the product of force and the perpendicular distance from the force’s line of action to the axis of rotation. It may be thought of as rotary force. Units = Newton-meters (N∙m) or a joule (J)

Answer 136

the perpendicular distance between the force’s line of action and the axis of rotation.

Answer 137

the ratio of force arm length to resistance arm length, hence MA = FA/RA

Answer 138

the amount of space that a body occupies.

Answer 139

force distributed over a given area. Units = N/cm2 P = F/A SI unit is the Pascal (N/m2). This is a very small pressure so kPa is a more common unit used.

Answer 140

pressing or squeezing force directly axially through a body

Answer 141

pulling or stretching force directly axially through a body

Answer 142

force directed parallel to a surface (i.e., a force that causes parts of a material to slide past one another in opposite directions).

Answer 143

F/A Similar to pressure.

Answer 144

depending on the torque angle, changes

Answer 145

1. If the object is very heavy, get someone to help you. Don't be a "hero". Use techniques that minimize the actual weight of the load being handled. 2. Stand facing the object with your feet flat on the floor, at shoulder width, and pointing straight ahead. Ensure that you have a stable base of support so that you don’t slip as you are lifting the load. 3. Face the object in the direction that you intend to move with it, so that you don't have to turn while holding the object. Avoid twisting and the simultaneous generation of high twisting torques. 4. Keep the object as close to your body as is convenient to minimize the reaction torque on the low back. 5. Get a good grip on the object so that you don’t lose control of it as you are lifting it. 6. Bend at the knees and hips and keep your back as straight as possible. Avoid a fully flexed or bent spine. 7. Lift the object using the knee and hip extensor muscles, not by pulling upwards with the arms and back. 8. Carry the object close to your center of gravity.

Answer 146

The flat back lifting posture has been found to be better overall than a rounded back in minimizing L5/S1 disc compressive force and ligament strain. Avoiding full flexion of the trunk ensures a lower shear load on the vertebrae and significantly lowers the probability of ligament damage. The probability of disc herniation is increased by repeated or prolonged full flexion of the trunk. One should never move immediately to a heavy lifting task from a stooped posture or after prolonged sitting. Standing for a brief period, and even consciously extending the trunk, will prepare the disc and posterior passive tissues to reduce risk of injury. Contraction of the abdominal muscles aids in supporting the vertebral column during lifting. Such support may significantly reduce both the forces required by the erector spinae muscles to perform a lift and the associated disc compressive forces. Avoid lifting or spine bending shortly after rising from bed. Forward bending stresses on the disc and ligaments are higher after rising from bed, compared with one to two hours later, causing discs to become injured at lower levels of load and degree of bending.

Answer 147

For the human body in anatomical position, the CG is approximately 5 cm anterior to the second sacral vertebra, or 6 cm below the belly button. On average, it is slightly higher in males than in females – 57 % versus 55 % of height. The exact location of the center of gravity varies from person to person depending on body proportions. The CG is influenced by changing body position or limb positions. The addition of external weight, such as a backpack, will relocate the CG. Segmentally, each body area contains its own center of gravity.

Answer 148

1. Used to describe the movement of the body through space 2. Important for stability 3. It is an important factor in calculation of amount of work done.

Answer 149

1. Reaction board method - used for a static position of the human body. Assume that the center of gravity is the fulcrum or balance point and then apply the Principle of Levers. 2. Segmental method - can be used for locating CG of a body in motion.

Answer 150

For balance to be maintained in any stationary position, the CG must remain over the base of support. Whenever the CG passes outside the base of support, the body is off balance in that direction. If a heavy object is carried close to the body's CG, there will be less likelihood of a loss of balance.

Answer 151

firmness of balance - can be increased by: 1. Increasing body mass 2. Increasing the size of the base of support in the direction of the line of action of an external force 3. Vertically positioning the CG as low as possible 4. Increasing friction between the body and the surface contacted 5. Horizontally positioning the CG near the edge of the base of support towards the oncoming external force

Answer 152

In a static equilibrium situation, there is no movement. You are in equilibrium (not falling) when your CG is within your base of support. In a dynamic equilibrium situation, when for example you want to change direction fast, you have to put your CG outside of the base of support. The more unstable you are, the faster you can change direction. And since you do not fall down, you are still in equilibrium, just dynamically.

Answer 153

First Law - Law of Inertia - “A body will maintain a state of rest or constant velocity unless acted on by an external force that changes the state.” The amount of inertia a body possesses is directly proportional to its mass. Second Law - Law of Acceleration - “force equals mass X acceleration” Third Law - Law of Reaction - “When one body exerts a force on a second body, the second body exerts a reaction force that is equal in magnitude and opposite in direction on the first body.”

Answer 154

A mechanical quantity that is important in situations involving collisions. Momentum = mass X velocity

Answer 155

Work = force X distance Units of work - 1.0 Nm = 1.0 J (joule) Power = work per unit of time = Fdt = force X velocity Units of power = watts - 1.0 W = 1.0 J/s.

Answer 156

Running speed = stride length X stride rate Length of stride is dependent primarily upon leg length and the power of the stride. Leg speed (frequency) is mostly dependent on speed of muscle contraction and neuromuscular coordination (skill) in running. Running mechanics vary from person to person and they vary in the same person running at different speeds. At slow running speeds, complete foot contact is used. As running speed increases, the amount of foot contact becomes less. At slower running speeds, runners tend to run more erectly, whereas at full speed, the typical sprinter leans forward at about 15 degrees from the perpendicular. Stride Frequency aka Cadence When fatiguing, what decreases most: stride length or cadence?

Answer 157

1. In running there is a period when both feet are off the ground. Consider running as a series of jumps. 2. In running, there is no period when both feet are in contact with the ground at the same time 3. In running, the stance phase is a much smaller portion of the total gait cycle than in walking. END OF MATERIAL FOR MIDTERM

Answer 158

Respiratory system consists of nose, pharynx, larynx, trachea, bronchi, and lungs.

Answer 159

primary, secondary, and tertiary bronchi ---> terminal and respiratory bronchioles ---> alveolar ducts ---> alveoli. With branching, supportive cartilage is gradually replaced by smooth muscle. Contraction and relaxation of this smooth muscle constricts or dilates the bronchioles --> major effects on airway resistance. The conducting airways lead inspired air to the alveoli. Volume of conducting airways = anatomic dead space (VD) - 150 mL.

Answer 160

small, thin walled sacs that have capillary beds in their walls; site of gas molecule (O2 & CO2) exchange between air and blood; there are millions (300) of alveoli 1 cell layer thick

Answer 161

alveolar-capillary membranes that separate the air molecules in the alveoli from the blood in the capillaries - average thickness is 0.6 micrometers. Fick’s Law of Diffusion The respiratory membrane has a very large surface area – 70 square meters in the normal adult - size of tennis court.

Answer 162

contain conducting airways, alveoli, blood vessels, elastic tissue.

Answer 163

Molecules move from areas of high pressure or concentration to areas of low pressure or concentration. Boyle's Law - the pressure of a gas is inversely proportional to its volume. P1V1 = P2V2 The movement of air into and out of the lungs results from a pressure difference between the pulmonary air and the atmosphere.

Answer 164

active process - diaphragm descends and external intercostal muscles contract thus increasing the volume of the thoracic cavity ---> decreased pressure in thoracic cavity causing a one or two mm Hg drop in intra-alveolar pressure at rest compared to the outside atmospheric pressure ---> air molecules move through the respiratory tubes into the lungs from the atmosphere following the pressure gradient. Inspiratory muscles, when they work their hardest, can produce a negative pressure as great as -30 mm Hg below atmospheric pressure within the alveoli.

Answer 165

passive process at rest. Secondary muscles, such as abdominal muscles become involved in exercise. Forced expiration can produce intra-alveolar pressure as great as +50 mm Hg above atmospheric pressure. During exercise, mouth breathing tends to replace nasal breathing - less resistance to airflow. Air that enters the respiratory passages via either the nose or the mouth is quickly saturated with water vapor and warmed to body temperature, 37 degrees centigrade, even under conditions when very cold air is inspired.

Answer 166

the amount of volume change in the lung for a given change in alveolar pressure.

Answer 167

Minute ventilation (V. E ) - 6 - 8 liters/min. Tidal volume (VT) - 500 mL per inspiration or expiration Breathing frequency (FR) - 12 - 16 breaths per minute Expiratory reserve volume (ERV) – approximately 25% of vital capacity (VC) Inspiratory capacity (IC) - approximately 75 % of vital capacity (VC) Total lung capacity = vital capacity plus residual volume (always have air left in lung) In maximal aerobic exercise, breathing frequency can increase up to 60 breaths per minute and tidal volume can increase up to 50 % of vital capacity.

Answer 168

the volume of air that reaches the alveoli per minute. This value is very important because this is the only air that participates in gas exchange with the blood. Upper vs lower case V^. A = (VT X FR ) - (VD X FR) = 500 mL X 12 - 150 mL X 12 = 6000 mL - 1800 mL = 4200 mL/min

Answer 169

1. Abdominal contents push up against diaphragm 2. There is an increase in intrapulmonary blood volume in the horizontal position that decreases the space available for pulmonary air.

Answer 170

Pulmonary function test norms are usually based on sex, age, and height. It is important to know the size and make-up of the population used to construct the norms. Problems with pulmonary function norms: - don’t consider the “size” of the subject, particularly the chest size - would be better to use sitting height rather than standing height Chronic pulmonary dysfunctions can be divided into two categories:

Answer 171

- blockage or narrowing of the airways causing increased airway resistance - asthma, bronchitis, emphysema. Bronchiolar obstruction can result from inflammation and edema, smooth muscle constriction, or bronchiolar secretion. Very difficult to move air rapidly in and out of lungs --> decreased FEV1.0, FEV1.0/VC much less than 80 %, decreased MBC Airways collapse during expiration before normal amount of air is emptied from the lung - air trapping ---> increased FRC, RV, TLC

Answer 172

- no problem with the airways but there is damage to the lung tissue - loss of elasticity and compliance - limited expansion of the lung - pulmonary fibrosis, pneumonia. All lung volumes are reduced - VC, RV, FRC, TLC - because the lung tissue is stiff and can't be expanded very far. FEV1.0 and MBC are reduced but FEV1.0/VC ratio is frequently 90% or greater. Pulmonary function tests must be interpreted in relation to a patient's medical history, occupational history, smoking habits, and a chest X-ray.

Answer 173

During exercise, minute ventilation increases linearly with increasing exercise intensity and oxygen uptake until approximately 60 % of V. O2max in untrained subjects and 75-80 % of V. O2max in endurance athletes. For a given individual, the exercise intensity at the ventilatory threshold is similar to the exercise intensity at the lactate threshold, the point at which lactic acid begins to accumulate in the blood. Prior to this exercise intensity, aerobic metabolism matches the energy requirement of the active muscles and no blood lactate accumulates because lactate production equals lactate disappearance. For a given work rate, arm or upper body exercise causes a greater minute ventilation than leg exercise – example of arm cycle ergometry versus leg cycle ergometry.

Answer 174

the point at which minute ventilation increases disproportionately with oxygen consumption during graded exercise.

Answer 175

I = V / R i.e., flow increases as the driving force increases flow decreases as the resistance increases This works well for electricity….what about a gas?

Answer 176

this is not an equation just to memorize, it is an equation to understand! This equation talks to us. Understand this equation and you understand how gas exchange occurs in every living organism on this planet. And still the equation tells us a lot more. Tells us about how our body works, how it evolved, and how it is affected by disease, and it is passive

Answer 177

this is not an equation just to memorize, it is an equation to understand! This equation talks to us. Understand this equation and you understand how gas exchange occurs in every living organism on this planet. And still the equation tells us a lot more. Tells us about how our body works, how it evolved, and how it is affected by disease, and it is passive

Answer 178

Evolution gives us 2 cell layers to diffuse totaling 0.6 mm to decrease Thickness Thus evolution has enhanced gas flow in and out of the lungs

Answer 179

Smoking increases Thickness and reduces Area Thus smoking is anti-evolution

Answer 180

Anything in your body is dependent on the rate of entry and rate of removal

Answer 181

happens when people pass out when lifting heavy weights, no air comes out of ur lungs The Valsalva Maneuver for Assessment of Cardiovagal Baroreflex Sensitivity Valsalva Maneuver in Pulmonary Arterial Hypertension: Susceptibility to Syncope and Autonomic Dysfunction

Answer 182

The circulatory system is composed of the heart, blood vessels, and blood.

Answer 183

transport essential materials (oxygen, fuel molecules, hormones, etc.) throughout the body to cells where they are needed and to collect waste materials (carbon dioxide, lactic acid, urea, etc.) generated by the body's metabolic activity.

Answer 184

(a) Pulmonary circuit - blood vessels going to and from the lungs (b) Systemic circuit - blood vessels going to and from the rest of the tissues of the body

Answer 185

The heart is a four chamber, muscular pump that propels blood through the blood vessels. Atria - the two upper chambers of the heart Ventricles - the two lower chambers A septum divides the left and right sides of the heart  two pumps. The right ventricle pumps blood through the pulmonary circuit while left ventricle pumps blood through the systemic circuit. The wall of the left ventricle is thicker than the wall of the right ventricle because the systemic circulation is a much higher pressure system than the pulmonary circulation. The direction of blood flow through the heart is controlled by unidirectional valves. Heart murmur - valve is damaged or does not close properly ---> blood regurgitates, causing a noise. The heart muscle (myocardium) is a specialized type of muscle - cardiac muscle. Unlike skeletal muscle, all of the fibers or cells in cardiac muscle are anatomically interconnected - functional syncytium. When one fiber contracts, all fibers contract. The fibers of the atria are separate from the fibers of the ventricles.

Answer 186

The heart's inherent contractile rhythm originates in an area of specialized tissue located in the posterior wall of the right atrium - the S-A node, the normal pacemaker of the heart. Pathway of conduction of the wave of depolarization (cardiac impulse) across the heart: Atrial muscle fibers  contraction S-A node A-V node  A-V bundle  left and right bundle branches  Purkinjie fibers which travel throughout the ventricular myocardium  simultaneous contraction of the left and right ventricles. The wave of depolarization is delayed in the A-V node for approximately 0.10 seconds in order to give the atria time to contract and empty their contents into the ventricles.

Answer 187

record the wave of depolarization as it passes across the heart using electrodes on the surface of the body. Components of a normal EKG (aka ECG) waveform: P wave - represents atrial depolarization QRS wave - represents ventricular depolarization T wave - represents ventricular repolarization

Answer 188

an irregularity in the rhythm of the heartbeat Diagnosing arrhythmias - look at heart rate, amplitude and shapes of the components of the EKG waveform, and time intervals. Examples of arrhythmias: a) atrial - tachycardia b) nodal - second and third degree heart blocks c) ventricular - premature ventricular contraction (PVC), ventricular tachycardia, ventricular fibrillation

Answer 189

The heart muscle is supplied by two major arteries that originate from the aorta just above the aortic valve - left coronary artery and right coronary artery. The large veins of the heart converge and empty into the right atrium. Widow maker Since cardiac muscle is highly dependent on aerobic metabolism, it has a rich blood supply. At rest, normal blood flow to the myocardium is about 5 % of the total cardiac output. Approximately 70-80 % of the oxygen is extracted from blood flowing in the coronary vessels compared to an average of 25 % in other tissues.

Answer 190

Arteries - blood vessels that carry blood away from the heart. They range in size from the aorta which is about 25 mm in diameter in man to those about 0.5 mm. Going from large arteries  medium-sized arteries  small arteries  arterioles, there is less elastic tissue in the wall of the artery and more smooth muscle. Arterioles - arteries under 0.5 mm in diameter By constricting or relaxing the thick layer of smooth muscle in the walls of arterioles, blood flow can be increased or decreased to various capillaries. Arteries and arterioles constitute the high pressure part of the circulatory system.

Answer 191

very tiny (7-8 microns diameter), thin-walled vessels. This is the site of exchange of nutrients and gases between the blood and tissues. All other organs of the circulatory system exist only to serve the capillary beds. Capillaries in the human body: - surface area = 6000 square meters (12 soccer fields) - 60,000 miles long - mass - twice the size of the liver

Answer 192

small vessels that conduct venous blood from capillaries to veins

Answer 193

Veins - vessels that convey blood toward the heart. In general, veins are of greater diameter, but thinner-walled than the arteries with which they travel. There are both superficial and deep veins Veins also have smooth muscle in their walls that allow them to change their diameter The venules and the veins constitute the low pressure part of the circulatory system. Valves - found in those veins which carry blood against the force of gravity, especially in the veins of the legs

Answer 194

a) Pressure difference between left ventricle and right atrium - 120 mm Hg - 3 mm Hg = 117 mm Hg driving pressure b) Skeletal muscle pump - active muscles squeeze the veins and push the blood towards the heart with the help of one-way valves c) Respiratory pump - decreased pressure in thoracic cavity during inspiration  easier for blood to return from lower portions of body via inferior vena cava  thoracic cavity  right atrium of heart

Answer 195

Blood is composed of specialized cells (red blood cells, white blood cells, and platelets) suspended in a liquid (plasma). Plasma makes up 50 to 60 % of blood by volume. The blood volume of the average adult with a normal body composition is approximately 8 % of body mass. Therefore, a person with a body mass of 70 kg has a blood volume of approximately 5.6 liters. Blood volume is greater for larger, more endurance trained, and altitude acclimatized people.

Answer 196

composed of about 90 % water and 10 % solutes.

Answer 197

- biconcave discs about 7-8 microns in diameter - in human blood - 5 to 6 million RBC per cubic millimeter of blood - hematocrit – the ratio of the volume of red blood cells to the total volume of blood, expressed as a percentage – usually 38-40 % in females and 45-47 % in males. - RBC's are continually being formed in red bone marrow in ends of long bones and in flat bones - lifespan of RBC = 120 days (1.5 million per second) - RBC contains hemoglobin which transports oxygen and carbon dioxide - hemoglobin is an iron containing protein which reversibly binds with oxygen Normal values for hemoglobin: Men – 14-16 grams per 100 mL blood Women – 12-14 grams per 100 mL blood

Answer 198

Two sites of gas exchange in the body: 1. Alveolar-capillary membrane in lung: - net diffusion of O2 from alveoli  blood - net diffusion of CO2 from blood  alveoli 2. Tissue-capillary membrance in tissues: - net diffusion of O2 from blood  tissue - net diffusion of CO2 from tissue  blood

Answer 199

Partial pressure of a gas - the pressure of a gas in a gas mixture is dependent on: (1) the total (barometric) pressure, and (2) the fractional concentration of that gas For example at sea level, the total pressure of all dry ambient (atmospheric) air gases equals 760 mm Hg which equals barometric pressure Composition of dry ambient air at sea level: Gas Concentration PartialPressure O2 20.93 % 0.2093 X 760 = ~160 mm Hg N2 79.04 % 0.7904 X 760 = ~600 mm Hg CO2 0.03 % 0.0003 X 760 = 0.1 mm Hg 100.00 % 760.0 mm Hg

Answer 200

Ambient air vs. tracheal air vs. alveolar air - partial pressure differences The functional residual capacity serves as a damper so that each incoming breath of air has only a small effect on the composition of the alveolar air  partial pressure of gases in the alveoli remains relatively stable.

Answer 201

Henry's Law - the amount of gas that dissolves in a fluid is a function of two factors: (1) The pressure of the gas above the fluid, which is given by the gas concentration times the barometric pressure (2) The solubility coefficient of the gas - CO2 is 20.3 times more soluble in water than O2.

Answer 202

Diffusing capacity for oxygen - the volume of oxygen that crosses the alveolar-capillary membrane per minute per millimeter mercury pressure between the alveolar air and pulmonary capillary blood.

Answer 203

. The thickness of the respiratory membrane - length of the diffusion path. Diffusing capacity is decreased in restrictive lung diseases such as pulmonary fibrosis or pneumonia. 2. The number of red blood cells or their hemoglobin concentration or both because bound O2 does not exert a partial pressure. 3. The surface area of the respiratory membrane available for diffusion - diffusing capacity is decreased in emphysema.

Answer 204

1. Increased lung volumes during exercise --> increased surface area for diffusion 2. Opening up of more capillaries in the lung and greater volume of blood flowing through the lung.

Answer 205

Ninety-eight percent of the oxygen in the blood is carried in red blood cells in chemical combination with hemoglobin. The other 2 % is dissolved in plasma. Hb + O2  HbO2. O2 carrying capacity of hemoglobin - one gram of hemoglobin becomes saturated with O2 when it combines with 1.34 mL of O2. Therefore if hemoglobin concentration equals 15.0 grams per 100 mL of blood, the O2 carrying capacity of the blood would be 15.0 X 1.34 = 20.1 mL of O2 per 100 mL of blood. Otherwise, if O2 was just dissolved in blood, the content would be ~0.3 mL O2/100 mL blood (60x less). Percent saturation of hemoglobin with O2 (%SO2) - relates the amount of O2 actually combined with hemoglobin to the maximum O2 capacity of hemoglobin

Answer 206

Hemoglobin is 97.5 % saturated with O2 - 97.5 % X 20.1 = 19.5 mL O2 per 100 mL blood

Answer 207

Hemoglobin is 75 % saturated with O2 – 75 % X 20.1 = 15.1 mL O2 per 100 mL blood Arteriovenous oxygen difference = 19.5 - 15.1 = 4.4 mL O2 per 100 mL blood. This represents how much oxygen is extracted or consumed by the tissues for each 100 mL of blood perfusing them.

Answer 208

- plot the percent saturation of hemoglobin (%SO2) versus the partial pressure of oxygen (PO2). Bohr Effect – increased body temperature, increased PCO2, and decreased pH shift the oxyhemoglobin dissociation curve to the right and release more oxygen at the tissue level for a given PO2. Hemoglobin acts as a tissue oxygen buffer system. The level of alveolar oxygen may vary greatly, from 60 to more than 500 mm Hg, and still the PO2 in the tissue doesn’t vary more than a few mm Hg from normal.

Answer 209

PAO2 - partial pressure of alveolar oxygen 104 mm Hg PACO2 - partial pressure of alveolar carbon dioxide 40 mm Hg Pa O2 – partial pressure of arterial oxygen for blood leaving 95 mm Hg the left ventricle PaCO2 - partial pressure of arterial carbon dioxide 40 mm Hg PvO2 - partial pressure of venous oxygen 40 mm Hg PvCO2 - partial pressure of venous carbon dioxide 45 mm Hg

Answer 210

Cardiac output ("Q. ") - the amount of blood pumped by either the left or right ventricle of the heart per minute. Both the left and right ventricles must have the same cardiac output so that blood flow through the pulmonary and systemic circuits is maintained equally. Stroke volume - the amount of blood pumped by either the left or right ventricle per beat. Cardiac output = heart rate X stroke volume

Answer 211

V. O2 = HR X SV X (CaO2-CvO2) diff where: V. O2 = oxygen uptake or utilization by the tissues in the body CaO2 = content of O2 in the arterial blood Therefore, in order to increase oxygen uptake, you must increase cardiac output and/or extract more oxygen from the arterial blood. In general, the higher the maximal stroke volume --> higher maximal cardiac output --> higher maximum oxygen uptake (V. O2max)

Answer 212

For any given subject, heart usually increases linearly with increasing work load until the subject's maximum heart rate is reached. The heart rate at a given oxygen uptake is higher when the exercise is performed with the arms than with the legs, just like ventilation Since: (1) the cardiac output required for a given work rate is reasonably similar for trained and untrained subjects, and (2) trained subjects have a higher stroke volume than untrained subjects --> then, for any given work rate, trained subjects will have a lower exercise heart rate.

Answer 213

Stroke volume = end-diastolic volume minus end-systolic volume Systole - the contraction phase of the cardiac cycle, when the ventricles pump out their stroke volumes. Diastole - the resting phase of the cardiac cycle, between heart beats End-diastolic volume (EDV) – the volume of blood in each ventricle at the end of diastole – 120 mL in an untrained person at rest End-systolic volume (ESV) – the volume of blood that remains in each ventricle after the ventricles have finished contracting – 50 mL in an untrained person at rest Ejection fraction – the percentage of EDV ejected with each contraction Stroke volume increases to its highest values during submaximal exercise (40 % VO2max, HR = 110 - 120) and then remains constant during the progression from moderate to maximal work.

Answer 214

greater systolic emptying = greater ejection fraction. The heart has a functional residual volume - at rest in the upright position, only 50 – 60 % of the blood in the ventricle is pumped out of the ventricle during the contraction - 50 to 80 mL of blood remains in the ventricle. During graded exercise, the heart progressively increases stroke volume by means of a more complete emptying during systole - due to effect of sympathetic hormones.

Answer 215

At rest 15-20 % of the systemic blood flow goes to the skeletal muscles. During maximal exercise 85 % of the cardiac output can be diverted to the working skeletal muscles. This increased blood flow to the working muscles is caused by: 1. Increased blood pressure 2. Dilation of arterioles in working muscles due to relaxation of the smooth muscle in the walls of the arterioles. 3.Constriction of arterioles in the gut area (liver, intestines, stomach, kidneys) and non-working muscles.

Answer 216

Resistance to flow = Fluid viscosity X Tube length Radius of tube 4 Thus decreasing tube radius by a factor of 2 will increase resistance to flow by a factor of 16, decreasing flow by a factor of 16. It has been calculated that a 33 % decrease in the radius of the arterioles will produce a 400 % increase in resistance to flow. Conclusion – only a small change in blood vessel radius dramatically alters blood flow.

Answer 217

Your arteries can "feel" the blood flowing, and respond to how hard it pushes and pulls. The cells that line them can change shape, move around and switch genes on and off in response to changes in pressure.

Answer 218

how much volume changes from pressure volume divided by pressure -arteries are less compliant

Answer 219

Merriam-webster.com defines it as “the maximum amount of oxygen the body can use during a specified period of usually intense exercise that depends on body weight and the strength of the lungs” And http://runneracademy.com defines it as “The basic definition of VO2 max is the maximum amount of oxygen your body can use during exercise. As a runner, this is used to measure your level of fitness.” We will form our own definition as the lecture progresses

Answer 220

The maximum oxygen uptake provides important information on the capacity of the oxygen transport system. The most important factors that determine V. O2max in a given person are the following: 1. The ability to ventilate the lungs and oxygenate the blood passing through the lungs 2. The ability of the heart to pump blood - cardiac output 3. The oxygen carrying capacity of the blood 4. The ability of the working muscles to accept a large blood supply 5. The ability of muscle fibers to extract oxygen from the capillary blood and use it to produce energy - oxidative enzyme levels, etc. As the duration of events requiring heavy continuous energy expenditure becomes progressively greater than one minute, aerobic capacity becomes increasingly important as a determining factor for success.

Answer 221

1. The test protocol should exceed 6 minutes but be less than approximately 15 min. 2. Incorporate a warm-up period - first stage of test 3. The test protocol should be arranged in stages, with each stage progressively increasing in intensity until the termination criteria is reached. Ramp versus step protocols

Answer 222

1. The oxygen consumption ceases to increase linearly with increasing work rate and approaches a plateau, the last two values agreeing within + 2 mL/kg/min. mL.(kg.min)-1 mL/(kg.min) mL.kg-1.min-1 2. Heart rate should be close to the age-predicted maximum (220 - age). This is test and protocol dependent. 3. Blood lactate levels should be 8 millimoles/liter or greater, 3-5 minutes post exercise. 4. Respiratory exchange ratio (V. CO2 divided by V. O2) should be greater than 1.10. 5. Subjective observations - did the subject look exhausted at the end of the test?

Answer 223

1. Untrained Canadian male (20-29 years) 40-50 2. Untrained Canadian female (20-29 years) 30-40 3. World class endurance athlete (M) 80-90 4. World class endurance athlete (F) 65-75 5. Soccer, ice hockey, basketball (M) 54-60 6. Baseball, football, thrower, sprinter 40-50

Answer 224

Highest reported values for V. O2max: Male - 94 mL∙kg-1∙min-1 - cross country skier Female - 77 mL∙kg-1∙min-1 - cross country skier

Answer 225

Since local muscle capillarization and aerobic enzyme levels are important determinants of V. O2max, athletes should ideally be tested in the mode of exercise used in their sport, i.e., rowers should be measured while rowing, cyclists while cycling, etc. In most subjects, the highest V. O2max values can be obtained during uphill treadmill running - 5-7 % higher than on a bicycle ergometer - due to activation of a larger muscle mass on the treadmill. However, competitive cyclists pedaling at a high frequency are able to achieve V. O2max values equal to or greater than their treadmill scores while cycling.

Answer 226

1. Mechanical - Monarch ergometers in Kines 142 lab 2. Electrically braked bicycle ergometer - resistance is provided by moving a conductor through a magnetic field.

Answer 227

1. Less expensive 2. Portable - can be used in field studies 3. Don't require electricity 4. Patient is more stable and body weight is supported - easier to collect physiological data during exercise - heart rate, blood pressure, oxygen uptake, blood samples, etc. 5. Easier to quantify work rate 6. Safer 7. Less noisy

Answer 228

1. Can't obtain as high a V. O2max as on a treadmill 2. Cycling is not a common mode of movement for most individuals. Walking is a far more common activity.

Answer 229

Based on research studies of identical and fraternal twins, current evidence indicates that V. O2max is 40 – 50 % genetically determined. Improvements in aerobic capacity with training normally range between 6 and 20 %.

Answer 230

V. O2max (liters/min) increases with age and reaches it's peak between 18 and 25 years of age. V. O2max then declines approximately one percent per year so that by age 55 it is on average 25-30 % below values reported for a 20 year old.

Answer 231

1. Decrease in maximum heart rate and negative changes in other components of the oxygen transport system. 2. As individuals grow older, they usually become less physically active. Sedentary individuals have nearly a two-fold faster rate of decline in V. O2max as they age as compared to physically active individuals. Before puberty, there is no significant difference in V. O2max between boys and girls. After puberty, the average male has a V. O2max (mL∙kg-1∙min-1) that is 20 - 25% higher than the average female.

Answer 232

1. Differences in body composition - male has more muscle and less fat - muscle is metabolically a more active tissue 2. Average male has a 10-14 % higher hemoglobin concentration In the normal population, there are many females who have V. O2max scores higher than less-fit males.

Answer 233

1. Less expensive and specialized equipment is required. 2. Tests can be submaximal – safety 3. Some tests can be administered to large groups 4. Less motivation is required from the subject

Answer 234

Procedures which use submaximal exercise heart rate to predict V. O2max are based on the following assumptions: 1. Linear relation between heart rate and oxygen uptake - true over a wide range of exercise intensities, but in some subjects at heavy work rates V. O2 increases relatively more than heart rate. 2. Similar maximum heart rate for all subjects - standard deviation is approximately 10 beats/min about the average maximum heart rate for people of same age group. Maximum HR declines with age - must use an age correction factor. 3. In cases where V. O2 is predicted from work rate, a fixed mechanical efficiency is assumed - mechanical efficiency may vary by 6 % on a bicycle ergometer. 4. Day to day variation in heart rate - even under highly standardized conditions (environmental temperature, time of day, diet, drugs, preliminary rest, clothing) the variation in submaximal heart rate is about 5 beats/min with day to day testing at the same work rate. The V. O2max predicted from submaximal heart rate is generally within 10 to 20 % of the person's actual value for normal subjects. The type of subject for whom these tests are poor predictors tends to be in the very low or very high V. O2max categories. Error in a well performed direct measurement of V. O2max is about 4 – 5 %.

Answer 235

The efficiency of muscular work is the percentage of chemical energy converted to mechanical energy, with the remainder lost as heat. Computation of mechanical efficiency: % EFF = Work performed (kcal) X 100 Energy expended (kcal) The efficiency of large muscle activities, such as walking, running, and cycling is usually 20 to 25 percent.

Answer 236

Some suggest the heart’s stroke volume limits V. O2max. This is based on training data and Fick’s principle. After training we see a 25 % increase in V. O2max and a 20 % increase in stroke volume. Extraction increases about 5 % and there is no change in maximum heart rate. Contrasting this is Fick’s law of diffusion equation and the actual equation actually used most often to calculate V. O2max. Where is stroke volume in these equations? Two contrasting ‘philosophies’ for limitation are the symmorphic and catastrophic theories. Symmorphosis implies that all links on the O2 cascade chain are of equal strength. Contrarily, catastrophe implies a weak link.

Answer 237

Why can a submaximal bike test predict VO2max? Why does an Olympic cyclist and the course instructor have the same efficiency on a bike ergometer? -efficiency is the same for everyone -same force to push the peddles which means same amount of cross-bridges Why isn’t stroke volume a major contributor to an increase in VO2max after training? -how can it be contributing if its not in the fixed equation.

Answer 238

% EFF = Work performed (kcal) X 100 Energy expended (kcal) = ATP produced * ATP used at XB 60 % * 40 %

Answer 239

VO2max provides an integrated measurement of your physiological systems that contribute to O2 transport and O2 utilisation including the cardiovascular, respiratory, neural, and muscular systems while maintaining body homeostasis.

Answer 240

A. Central Nervous System 1. Brain - newer more sophisticated regions are piled on top of older, more primitive regions a) Forebrain (i) Cerebrum constitutes about 80 % of total brain weight - cerebral cortex, basal nuclei (ii) Diencephalon - thalamus, hypothalamus b) Cerebellum c) Brainstem - continuous with the spinal cord - medulla, pons, midbrain 2. Spinal cord - long cylinder of nerve tissue which extends down from the brainstem to the second lumbar vertebrae. It is 45 cm long and 2 cm in diameter. Protected by the vertebral column and associated ligaments and muscles, the spinal meninges and the cerebrospinal fluid.

Answer 241

Consists of 12 pairs of cranial nerves and 31 pairs of spinal nerves 1. Afferent division - conveys information from the sensors in the periphery to the central nervous system (CNS) 2. Efferent division a) Somatic nervous system - nerve fibers innervate skeletal muscle b) Autonomic nervous system - nerve fibers innervate smooth and cardiac muscle and glands (i) sympathetic division (ii) parasympathetic division Neuroglia. They occupy about half of the volume of the brain. The four major types of glial cells serve as the connective tissue of the CNS and as such help support the neurons both physically and metabolically. It is estimated that there are approximately 100 billion neurons in the brain and a similar number of neuroglia (Bartheld et al., 2016). Along with the endocrine system, the nervous system regulates and coordinates the various functions of the body.

Answer 242

Neuron – a nerve cell. A neuron is specialized to transmit electrical signals. It consists of: 1. Cell body - soma - contains the nucleus 2. Axon - a long fiber that conducts impulses away from the cell body. The term "nerve fiber" is generally used in reference to an axon. 3. Dendrite - short projections from the cell body that transmit impulses toward the cell body The main purpose of the neuron is to pass messages (impulses) from one part of the body to another Myelin sheath - a discontinuous sheath around the axon. It is composed mainly of lipid and protein. Nodes of Ranvier - spaces between the segments of myelin sheath --> saltatory conduction Myelinated nerve fibers have much faster conduction velocities than unmyelinated fibers Synapse - the connection of an axon of one nerve to the cell body or dendrites of another nerve.

Answer 243

1. Afferent neurons - carry impulses from the sensory receptors into spinal cord or brain 2. Efferent neurons - transmit impulses from the CNS out to the effector organs - muscles (motor neurons) and glands 3. Interneurons - lie entirely within the CNS. They account for 99 % of all nerve cells. Each spinal nerve is actually a nerve trunk - it contains hundreds of individual afferent and efferent nerve fibers that are bound together by connective tissue sheaths.

Answer 244

Resting membrane potential - due to the selective permeability characteristics of the nerve cell membrane, a potential difference (voltage) exists between the inside and outside of the nerve fiber. A high concentration of positive sodium ions on the outside of the nerve membrane causes it to be electrically positive, while the inside of the nerve is electrically negative. Action potential - an appropriate stimulus suddenly causes sodium ions to rush to the inside of the nerve --> reversal of polarity. Once the action potential is started, it spreads ‘slowly’ along the entire length of the axon or fast by saltatory conduction.

Answer 245

Nervous information is relayed across the synaptic cleft by means of a chemical transmitter substance. Transmitter substances can be either excitatory or inhibitory in their effects on the post synaptic membrane potential Spatial vs. temporal summation Neuromuscular junction - nerve to muscle synapse. The chemical transmitter substance is acetylcholine.

Answer 246

The spinal cord is enlarged in two regions for innervation of the limbs: a) The cervical enlargement that extends from the C4 through T1 segments of the spinal cord b) The lumbosacral enlargement that extends from the T11 through L1 segments of the spinal cord Plexus – a network of converging and diverging nerve fibers, or blood vessels. The brain and spinal cord are composed of gray matter and white matter. The nerve cell bodies lie in and constitute the gray matter while the interconnecting tracts of nerve fibers (axons) form the white matter. Structure of spinal nerves – 31 pairs of spinal nerves are attached to the spinal cord – 8 cervical, 12 thoracic, 5 lumbar, 5 sacral and 1 coccygeal Each spinal nerve has a dorsal root and a ventral root connected to the spinal cord. The dorsal roots contain afferent (sensory) fibers that carry information from the periphery to the spinal cord and brain. The ventral roots contain efferent (motor) fibers to the skeletal muscle. The cell bodies of the motor axons making up the ventral roots are located in the ventral gray horns of the spinal cord. The cell bodies of the sensory axons making up the dorsal roots are outside of the spinal cord in the spinal ganglia.

Answer 247

a collection of nerve cell bodies located outside of the CNS.

Answer 248

transection of the spinal cord results in loss of all sensation and voluntary movement inferior to the point of damage. The patient is quadriplegic if the cord is transected superior to C5. If the transection is above C4, the patient may die of respiratory failure. The patient is paraplegic – paralysis of both lower limbs - if the transection occurs below the cervical segment of the spinal cord. Deficiency of blood supply (ischemia) to the spinal cord caused by fractures, dislocations, atherosclerosis, etc affects its function and can lead to muscle weakness and paralysis. When the brain or spinal cord is damaged, in most cases the injured axons do not recover.

Answer 249

Proprioceptors - conduct sensory information to the CNS from muscles, tendons, ligaments, and joints --> kinesthetic sense Finger point Going to dentist

Answer 250

Structure - several modified muscle fibers, four to 10 millimeters in length, contained in a capsule, with a sensory nerve spiralling around its center. Spindle fibers (intrafusal fibers) lie parallel to the regular fibers (extrafusal fibers). Function - send information to the CNS regarding the degree of muscle stretch --> activation of the exact number of motor units to overcome a given resistance. With increasing degrees of stretch of the muscle spindle, the frequency of impulse transmission up the afferent neuron to the spinal cord progressively increases.

Answer 251

1. Tonic stretch - concerned with the final length of the muscle fibers 2. Phasic stretch - spindle responds to the velocity of the rate of length change - overshoot 3. Gamma system - gamma efferent fibers innervate the contractile ends of the intrafusal fibers. When the alpha motor neurons are activated, the gamma motor neurons are also activated (coactivation). Gamma system provides the mechanism for maintaining the spindle at peak operation at all muscle lengths. Stretch reflex Muscle spindles are distributed throughout the muscle. Their density varies with the degree of control required by a given muscle.

Answer 252

Location - encapsulated in tendon fibers near the junction of the muscle and tendon fibers. They are approximately one millimeter long and 0.1 millimeters in diameter. They are in series with the muscle fibers rather than in parallel as are muscle spindles. When a muscle contracts, the GTO is stretched. Functions - the firing rate of the GTO is very sensitive to changes in the tension of the muscle. 1. Sensory input from GTO about the tension produced by muscles is useful for a variety of motor acts, such as maintaining a steady grip on an object. 2. When stimulated by excessive tension or stretch --> send sensory information to the CNS --> causes the contracted muscle to relax (reflex inhibition) - protect the muscle and its connective tissue harness from damage due to excessive loads

Answer 253

Supply information to the CNS concerning joint angle, acceleration of the joint, etc

Answer 254

The cerebral cortex and cerebellum are the main centers employed in learning new motor skills. These areas of the brain initiate voluntary control of movement patterns.

Answer 255

Primary motor cortex - located at the rear of the frontal lobe of the cerebral cortex. Stimulation of different areas of the primary motor cortex brings about movement in different, specific areas of the body. Contains the motor homunculus. However, no coordinated movement can be elicited. The motor cortex on each side of the brain primarily controls muscles on the opposite side of the body. Pyramidal tract - corticospinal pathway - long axons which carry impulses from the primary motor cortex where their cell bodies are located directly to lower motorneurons in spinal cord ---> spinal nerves The corticospinal system primarily mediates performance of fine, discrete, voluntary movements of the hands and fingers.

Answer 256

one of the three higher areas that command the primary motor cortex. Located on the lateral surface of each cerebral hemisphere in front of the primary motor cortex. Extrapyramidal tract - multineuronal pathways - route used to send impulses from the premotor area down to the lower motorneurons of the spinal cord. Instead of synapsing directly with motor neurons, this pathway involves many of the other brain regions, including the cerebellum. These pathways are more concerned with posture and coordination of large muscle groups Considerable complex interaction and overlapping of funcion exist between these two systems.

Answer 257

Located behind the brainstem. It functions by means of intricate feedback circuits to monitor and coordinate other areas of the brain involved in motor control. It receives signals concerning motor output from the cortex and sensory information from receptors in muscles, tendons, joints and skin, as well as from visual, auditory and vestibular end organs. The cerebellum determines an error between the expectations of the motor skill and the feedback reality of the motor performance. This error signal enables motor learning. Function - the major comparing, evaluating, and integrating center for postural adjustments, locomotion, maintenance of equilibrium, perceptions of speed of body movement, and general motor coordination. Damage to the cerebellum results in impaired motor control. Recent studies have shown that this motor comparator function the cerebellum performs is extended to include cognitive functions: quality control of our thoughts.

Answer 258

Why do all cells have a membrane potential? negative charge stays in the cell and attracts positive and gets drawn into the cell and creates a chemical gradient to go out and when in balance we reach resting membrane potential. Why do Schwann cells increase nerve conduction velocity? Why do you have kinesthetic sense? Why does the thigh muscle shorten after a patellar tendon tap? cuz the muscle doesnt stretch a long way but stretches really quickly Why does the cerebellum control movement?

Answer 259

a relatively permanent change in the performance levels of a motor task as the result of practice.

Answer 260

Motor Skill - denotes an act or task that has a goal to achieve and that requires voluntary body or limb movement to be properly performed. The acquisition of a motor skill is a process in which the learner develops a set of motor responses into an integrated and organized movement pattern. Skill, unlike talent, is a consequence of training and practice. Not a reflex

Answer 261

1. Production of a fast output of high quality. 2. An appearance of ease and smoothness of movement. 3. An anticipation of variations in the stimulus situation before they arrive. 4. Reduction in time to make a choice of responses once the signal is identified.

Answer 262

1. Input variables - involve the capacity of a performer to understand directions, to judge velocities of objects in a complex space field, as well as his ability to perceive his own movements. (Jim Thorpe could not hit a curve ball) 2. State of the performer - maturation, tension and arousal, motives, etc. (chuk knoblack, steve sax, george knudson) 3. Nature of the practice afforded - whether practice is massed or distributed, whether a skill is practiced as a whole or in parts, or whether the skill is a component in a series.

Answer 263

Determine which components of a skill are common or similar to components of another skill. For each classification system, consider each of the two categories as extreme ends of a continuum.

Answer 264

This classification system is most commonly used in special education, adapted physical education, and rehabilitation. Gross motor skills - involve large musculature as the primary basis of movement - walking, throwing, jumping, most sport skills. While precision of movement is not an important component, the smooth coordination of movement is essential to the skilled performance of these tasks. Fine motor skills - skills that require the ability to control small muscles of the body to achieve the successful execution of the skill. Generally, these skills involve hand-eye coordination and require a high degree of precision of movement - writing, drawing, piano playing, watch making Physical therapists usually work with gross motor skills while occupational therapists work on fine motor skills.

Answer 265

This classification system is most commonly used by motor learning researchers and in human engineering and human factors. Discrete motor skill - clearly defined beginning and end points - throwing a ball, pushing in the clutch in a car, hitting a key on a computer Continuous motor skill - has arbitrary beginning and end points. The performer or some external force determines the beginning or end point of the skill rather than the skill itself - steering a car, tracking tasks such as using a pursuit rotor, swimming, running, etc. Serial motor skill (combination) – of course we can combine a series of discrete skills. Each skill consists of a specific series of movements that must be performed in a specific order for proper execution of the skill. An example would be shifting gears in a car.

Answer 266

This classification system is most commonly used in physical education. Closed skills - the performance environment is stable and predictable - golf, bowling, archery, weightlifting, swimming, etc. These skills are self-paced or internally paced. The stimulus waits to be acted on by the performer. Require similar responses each time a response is required Open skills - the performance environment is constantly changing and is therefore much less predictable - hitting a tennis ball, racquetball, baseball, etc., team sports The performer is required to make rapid modifications in her plan of action to match the demands of the situation. The performer must act according to the action of the object or the characteristics of the environment. Externally paced task

Answer 267

Although the transition from an unskilled to a skilled performer may be regarded as a continuous process, it has been suggested that a number of clear stages can be identified (Fitts and Posner): 1. Cognitive Stage: 2. Associative Stage: 3. Autonomous Stage:

Answer 268

Performer needs to understand what has to be done - coach gives repeated visual demonstrations and verbal explanations Performer is concerned with organization of which movements to make rather than how to make them Performer is attempting to form a mental plan of the performance that will govern his actions Errors are made frequently and tend to be large Performance is highly variable In the attempts made to improve the skill, the responses are changed frequently Coach gives diagnostic knowledge of results (KR)

Answer 269

Performer moves to this stage when he is able to reproduce a reasonable approximation of the desired movement In this stage, the task of the performer is to refine the necessary movements required for the execution of the task Errors are no longer large Performers are now able to recognize errors without always having their attention directed to them by the coach Concerned with how to do rather what to do Performer is slowly learning to use proprioceptive rather than visual information Larger and larger parts of the skill come under automated control

Answer 270

Advanced performers are at this stage Movements that make up the motor responses have been automated and, where appropriate, spare attention may be devoted to other tasks such as, for open skills, game strategy. This stage is the result of a tremendous amount of practice There is a good degree of similarity between highly practiced skills and reflexes. Variability of performance is small Small improvements in skill do continue in this stage Learners do not make abrupt moves from one stage to the next ---> continuum

Answer 271

Are some people naturally more gifted than others? Can you teach anybody a motor skill? Does nature versus nurture play a role? Maybe with years and years of training I could learn to compose a symphony:- Mozart did it at the age of 4. 15 young subjects were given piano lessons for 6 weeks. They showed a large variation in learning. fMRI of the brain revealed the areas of the brain that changed with learning. Interestingly, other active brain areas that did not change with practice were used to predict learning rate. This suggests that these areas represent talent.

Answer 272

KP is information about a learner's response provided from an external source (teacher, coach, videotape) after completion of the response. KP is augmented feedback. KP is especially important for learning in the early stages because the learner has not developed an internal standard of correct performance. Distinction between KP and sensory feedback - vision, sound, proprioception, etc. KP serves 3 important functions in learning - to guide error correction, to reinforce correct performance, and to motivate the individual toward achieving a performance goal.

Answer 273

No more or no less information about a performance should be provided than the learner is capable of handling. KP must provide information that will direct attention to the part of the skill that must be corrected and it must provide information that will enable the learner to make an appropriate correction. The time the learner has to use the information provided to him following a practice response is very critical. Person should be given sufficient time to put the information to use to determine how to respond next time. KP should not be given on every trial.

Answer 274

1. KP-Delay interval - follows completion of a response and precedes presentation of KP (critical time period: cannot be too short) 2. Post-KP interval - follows presentation of KR and precedes the next response (critical time period: cannot be too short) 3. Inter-response interval - the total time between the two responses

Answer 275

The skill level of the student is a critical factor - beginners need the aid of an instructor to point out information from the replay. It is important that the replays be used for periods of at least 5 weeks. Meaningful information must be presented. The use of videotape for KP involves the same problems as verbal KP.

Answer 276

Transfer of learning is the influence of a previously practiced skill on the learning of a new skill - handball vs. squash; pitching machine in baseball

Answer 277

occurs when experience with a previous skill aids or facilitates the learning of a new skill The higher the degree of similarity between the component parts of two skills or two performance situations, the greater the amount of positive transfer that can be expected between them.

Answer 278

occurs when experience with a previous skill hinders or interferes with the learning of a new skill. - forehand in tennis and badminton Negative transfer effects occur when a new response is required for an old stimulus, e.g., having to type on a computer keyboard that is different from the one that you are familiar with. Negative transfer will generally be seen only in specific aspects of an activity. Negative transfer affects are typically temporary; they are usually overcome rather quickly with practice

Answer 279

experience with a previous skill has no influence on the learning of a new skill - learning to swim and learning to drive a car The transfer of learning concept is very important in the teaching of motor skills - teaching basic swimming strokes using dry land drills before letting students try the strokes in the water, using a pitching machine to teach hitting in baseball, etc.

Answer 280

involves the improvement in performance of one limb as a result of practice with the opposite limb. This is important in motor skills such as dribbling a basketball, kicking a soccer ball, etc. Available evidence indicates that greater transfer can be expected to occur from the preferred limb to the non-preferred limb. handout Bilateral transfer effects are the result of both cognitive and motor factors. Results indicate that bilateral transfer occurs faster when one limb is practiced to a reasonable degree of proficiency before practice is begun with the other limb

Answer 281

The purpose of practicing a skill is to learn to perform that skill in situations where you will in some way be tested. Establish practice conditions that will lead to maximum test performance. It is essential to have a variety of practice experiences involving variations of the skill being learned so that a person can successfully perform the skill in a variety of performance situations.

Answer 282

Increasing the variability within each practice session is preferred to practicing one variation during one session, another variation in another session, etc. The amount of practice affects the quality of learning although the effect is not always proportional. What form of instruction or practice will yield the greatest returns for the least expenditure of time? The spacing or distribution of practice can affect both practice performance and learning.

Answer 283

Mental practice - the cognitive rehearsal of a physical skill in the absence of overt, physical practice. It involves imaging the actual correct performance of the movement. Reinforce a proper response as an aid to an upcoming response. Example of a golfer and a gymnast. Mental practice, when used properly, can be an effective aid in the acquisition, performance, and retention of motor skills. Its implementation requires effective planning by the teacher and use by the students. One benefit of mental practice - in a large class, students can be instructed to mentally practice a certain number of movements or exercises while they are waiting their turn to use equipment.

Answer 284

1. Trial Performance 2. Retention Tests 3. Transfer Tests

Answer 285

Why do we need intrinsic feedback? Why does motor performance no always reflect motor learning?

Answer 286

Think about “deep processing” we learned in week 1: better connections were made

Answer 287

deltaTc ~= M - E +/- R +/- Cd +/- Cv

Answer 288

the exchange of electromagnetic energy waves emitted from one object and absorbed by another. At room temp and naked, 60 % of your heat loss will be by radiation. Manhattan effect

Answer 289

occurs whenever two surfaces with differing temperatures are in direct contact. Insulators - do not conduct heat readily. Still air is an excellent insulator, while water is an excellent conductor. Heat conduction in water is about 25 times greater than in air because…… The rate of conductive heat exchange is inversely related to the thickness of the insulating substance - air trapped in goose down clothing, body fat, layer principle of dressing for the cold.

Answer 290

requires that one of the media be moving as occurs with a fluid or gaseous medium. For example, heat transfer from skin to moving air or water. Wind Chill Index - gives the equivalent still air temperature for a particular ambient temperature at different wind velocities. The temperature gradient between the skin and air and the air velocity are important factors in determining convective heat loss. Convective heat loss during swimming is more than twice that during rest in still water.

Answer 291

the transfer of heat from the body surface through the change of liquid water on the skin to a gaseous water vapour in the environment. hyponaturemia loose water and salt but only replace the water -nausea, cramps, convulsions, slurred speech

Answer 292

There are two primary physiological responses used by humans to defend against a cold environment: 1. Increase in metabolic rate a) Voluntary - exercise - can increase heat production 10-20 times the basal rate b) Involuntary - shivering - can increase basal rate 3-4 X below 32 C core temp shivering stops We feel cold at about 25 C environmental temp 2. Increased tissue insulation - vasoconstriction of peripheral blood vessels and shunting of blood flow into deeper vessels. Because the superficial blood vessels in the head do not constrict in the cold, the head is an important source of heat loss - accounts for 30 – 35 % of total heat loss at rest. Behavioural responses to the cold are important - clothing, seeking shelter, starting a fire, etc. Lightning strike

Answer 293

A. Skinfold Thickness The thicker the fat layer, the greater the insulation. B. Gender The average female has more subcutaneous fat than the average male  more insulation. However, women generally have larger surface area to mass ratios than men. Children have even higher surface area to mass ratios. When men and women with similar skinfold thicknesses are compared, women lose heat more rapidly than men during immersion in cold water.

Answer 294

The effective insulation afforded by clothing is a function of the air layer next to the skin, the thickness of the clothing, and the air trapped between the layers of clothing. More clothing insulation is needed during rest than during exercise. Clothing insulation is reduced if the clothing becomes wet. Multiple layers of clothing are advisable during exercise in cold weather. The outer layer should be water repellent and wind resistant. Middle layers should provide insulation. The innermost clothing layer should not only provide insulation but also wick moisture away from the skin to reduce evaporative heat loss – polyester or polypropylene thermal underwear. Clothing insulation is reduced if wind penetrates the outer garments.

Answer 295

Hypothermia - a condition characterized by a body core temperature below 35oC. Body core - refers to brain, heart, lungs, blood, liver, kidneys. Critical areas for heat loss - head and neck, sides of chest, groin. Shivering will cease when core temperature (Tc) falls below 32-34oC. Death occurs when Tc drops to 24-28oC. Edmonton 13 month old at -20 C in a diaper Stage 1, body temperature drops by 1-2°C below normal temperature Stage 2, body temperature drops by 2-4°C. Stage 3, body temperature drops below approximately 32 °C (89.6 °F).

Answer 296

1. Immersion in cold water or wet clothing 2. Wind 3. Physical exhaustion 4. Inadequate clothing for conditions 5. Low percent body fat 6. Hypoglycemia  no shivering 7. Alcohol consumption - causes a decrease in shivering, increased blood flow to skin, impairs judgement. Hypothermia causes the oxyhemoglobin dissociation curve to shift to the left  increased hemoglobin affinity for O2  less O2 is released to the tissues  body tissues shift to anaerobic metabolism  hypoxia of heart and brain plus metabolic acidosis  depressed brain function and cardiac output  ventricular fibrillation and death.

Answer 297

Freezing of superficial tissues that occurs when skin temperature reaches between minus 2 to minus 6 degrees C. Many people are unaware of frostbite because the sensory nerves are blocked and the skin is numb.

Answer 298

Inhaled air is conditioned as it enters the upper respiratory passageways – warmed to 37oC and saturated with water vapor. Therefore you can’t “freeze” your lungs when exercising in very cold weather. Since cold air is very dry  cells lining the respiratory passageways become dry  possibility of throat irritation.

Answer 299

When Tc is decreased, V. O2max is decreased due to decreased maximum heart rate and shift of the oxyhemoglobin dissociation curve to the left. V. O2 = HR X SV X (a-vO2) diff For a given exercise intensity, a person is working at a higher percentage of V. O2max when core temperature is decreased  use glycogen stores at a faster rate  earlier onset of fatigue. Reduced blood flow to muscle when body is cooled  more anaerobic metabolism

Answer 300

All of the following are decreased: • strength and power • nerve conduction velocity • reaction time • manual dexterity • flexibility

Answer 301

Pressure of air at sea level = one atmosphere or 760 mm Hg The weight of a column of water directly above a diver's body (hydrostatic pressure) increases directly with increasing depth. The pressure increases by one atmosphere for each additional 33 ft of depth. 33 ft = 2.0 atmospheres 66 ft = 3.0 atmospheres Because the tissues of the body are largely water, they are non-compressible. However, the body contains air cavities - lungs, respiratory passages, sinus and middle ear spaces - where volume and pressure will change with increases or decreases in diving depth. Boyle's Law - the volume of any gas varies inversely with the pressure on it, i.e., if the pressure is doubled, volume is halved.

Answer 302

A. Snorkeling There are limits to snorkel size because: 1. Pressure effects - when breathing through a snorkel, the diver must inspire air at atmospheric pressure. At a depth of only 3 ft, the compressive force of water against the chest cavity is so large that the inspiratory muscles are usually unable to overcome external pressure and expand the thoracic cavity. 2. Increase in pulmonary dead space: Normal anatomical dead space = 150 mL. Dead space of regular snorkel = 150 mL. VA = VT - VD At rest: 350 mL = 500 mL - 150 mL With snorkel: 350 mL = 650 mL - 300 mL As snorkel size increases, VD increases and it becomes more difficult to maintain VA.

Answer 303

As the skin diver descends, the air in the lungs is compressed  lung squeeze. When lung volume is compressed below residual volume  lung damage occurs as blood is sucked from the pulmonary capillaries into the alveoli "Normal" maximal breath holding time after a maximal inspiration of ambient air is approximately 50 - 60 seconds. The arterial PO2 then drops to about 60 mm Hg and the arterial PCO2 rises to 50 mm Hg. Hyperventilation prior to breath-hold diving can significantly extend the breath-hold time. This is very dangerous due to the risk of blackout – loss of consciousness in the water. Hyperventilate forcefully for one minute - can decrease PaCO2 from normal value of 40 mm Hg to 15-20 mm Hg. Normal PaO2 = 100 mm Hg. Unconsciousness will occur when PaO2 decreases to approximately 30 mm Hg.

Answer 304

Diver hyperventilates, holds breath, and dives down to a certain depth  gases in lung are compressed and partial pressures are increased  diver holds breath as long as possible and then starts to ascend  partial pressure of gases in lung decrease on ascent  PaO2 decreases below critical point  diver loses consciousness and drowns.

Answer 305

Scuba - self contained underwater breathing apparatus Equipment needed for scuba diving: - mask and snorkel - clothing - wetsuit or drysuit, gloves, hood, fins, boots - weight belt - buoyancy compensator - tank and backpack - depth gauge and pressure gauge - single hose, two-stage regulator The two regulators reduce the air pressure in the tank from approximately 2500 psi (when tank is full) to exactly the ambient water pressure at the diver's mouth. Underwater breathing systems must supply air at sufficient pressure to overcome the force of water against the diver's chest. Open-circuit scuba - used by sport divers - as diver starts to inspire, slight negative pressure causes inspiratory valve on demand regulator to open  air enters diver's lungs. On exhalation, the exhaled air is discharged into the water.

Answer 306

Embolus - any material that enters and obstructs a blood vessel. Diver inflates lungs and begins ascent from depth  diver doesn't exhale  pressure decreases as he ascends  air in alveoli expands (Boyle's Law) to the point where alveoli rupture  air bubbles enter blood vessels  block an artery in heart (heart attack) or brain (stroke) or other area  possibility of death Even with rapid, expert treatment, 16 % of air embolism victims die. Rule - never hold your breath while scuba diving

Answer 307

Rupture of alveoli  air pocket forms outside the lungs between the chest wall and lung tissue  continued expansion of this trapped air during ascent causes the ruptured lung to collapse

Answer 308

At depths over 100 ft, the increased partial pressure and quantity of dissolved nitrogen produces an anesthetic effect on the central nervous system – effects similar to alcohol intoxication  decreased awareness of cold, hallucinations, decreased attentiveness, reckless behaviour. Dependent primarily on the depth of the dive and secondarily on the length of time at that depth.

Answer 309

Also called "decompression sickness" If the diver ascends to the surface too rapidly after a deep, prolonged dive, dissolved nitrogen moves out of solution and forms bubbles in body tissues and fluids. Pain is usually first felt around joints within four to six hours after the dive. If bubbles lodge in an artery  permanent damage or death. Treatment: recompression in a hyperbaric chamber to force the nitrogen gas back into solution and then slow decompression Prevention: - ascend to the surface in stages - decompression stops to allow sufficient time for nitrogen to diffuse from the tissues to the blood without bubbles forming. - follow the recommendations of standard decompression tables with regard to ascent patterns

Answer 310

Occurs when the inspired PO2 exceeds 1520 mm Hg for longer than 30-60 minutes Effects: - irritation of respiratory passages which progresses to pneumonia if exposure continues - muscle twitching - confusion, nausea - convulsions

Answer 311

The term "squeeze" can be applied to all the troubles that pressure can cause during descent, as a result of pressure differentials between two structures or spaces. Mask should cover eyes and nose so that pressure inside the mask can be equalized with the outside ambient pressure during descent by occasionally blowing air out the nose. If pressure is not equalized, a relative vacuum is created within the mask  blood vessels in and around the eyes rupture as the eyes bulge out of their sockets. Don't dive below 8 feet when wearing goggles.

Answer 312

Eustachian tube - a small membrane lined passage connecting the middle ear cavity and the back of the throat Purpose - equilibrate the pressure within the ear cavity with the outside by transferring air to or from the lungs. If the eustachian tube is either partially or totally blocked (anatomical problem or respiratory infection), increasing pressure against the eardrum during descent is not met by an equal force from the interior  a relative vacuum is created in the middle ear  hemorrhage of tissues in the middle ear (equalization of pressure by bleeding) and possible rupture of the eardrum Symptoms - pain in the ears after descending only a few feet. Pain rapidly becomes severe as the descent continues.

Answer 313

Why do we have a wind chill index? Why do we have a humidity index? Why do some people who exercise suffer hyponatremia? Why do some people drown while breath holding underwater? because they hyperventilate first Why do divers suffer the bends? the disend too fast