Age and Sex Considerations in Sport and Exercise

Question 1

What are some physiological responses to acute exercise when a person is growing?

Answer 1

• Strength
• Cardiovascular, respiratory function
• Metabolic function
– Aerobic capacity
– Running economy
– Anaerobic capacity
– Substrate utilization
• Strength as muscle mass with age
– Peaks at ~20 years for women
– Peaks at 20 to 30 years for men
• Strength, power, skill require myelination
– Peak performance requires neural maturity
– Boys experience marked change at ~12 years
– Girls more gradual, linear changes

Question 2

What are some physiological responses in terms of the CV system when a person is growing?

Answer 2

• Resting and submaximal blood pressure
– Lower than in adults (related to body size)
– Smaller hearts, lower peripheral resistance during
exercise
• Resting and submaximal stroke volume, HR
– Lower SV: smaller heart, lower blood volume
– Higher HR: almost compensates for low SV
– Slightly lower cardiac output than an adult
– (a-v-)O2 difference will increase to further compensate
• Maximal HR higher than in adults
• Maximal SV lower than in adults
• Maximal cardiac output lower
– Limits performance: less O2 delivery
– Not a serious limitation for relative workloads

Question 3

What are some physiological responses to acute exercise in terms of lung function when a person is growing?

Answer 3

• Lung function
– Lung volume increases with age
– Peak flow rates increase with age
– Postpuberty: girls’ absolute values lower than boys’
due to smaller body size

Question 4

What are some physiological responses to acute exercise in terms of metabolic function when a person is growing?

Answer 4

– Increases with age
– Related to muscle mass, strength, cardiorespiratory
function

Question 5

What are some CV changes in response to acute exercise in a growing person?

Answer 5

• Cardiorespiratory changes during exercise
accommodate muscles’ need for O2
• Cardiorespiratory changes with age permit
greater delivery of O2
– V•O2max in L / min increases with age (boys, girls)
– V•O2max in ml / kg / min steady with age in boys
– V•O2max in ml / kg / min decreases with age in girls
– L / min more appropriate during growth year

Question 6

How would one approach scaling data for size?

Answer 6

• V•O2max relative to body weight is
considerably different from absolute values,
as shown in figure 17.7
• Using body surface area or weight to the
0.75 power is the best way to reduce the
effect of body size on data

Question 7

What are some physiological responses to acute exercise in children?

Answer 7

• Children’s economy of effort worse than
adults’
– Child’s O2 consumption per kilogram > adult’s
– With age, skills improve, stride lengthens
• Endurance running pace increases with age
– Purely result of economy of effort
– Occurs regardless of V•O2max changes, training
status

Question 8

Explain the differences between a child’s vs. an adult’s anaerobic capacity for exercise?

Answer 8

• Children limited anaerobic performance
compared to adults
• Lower glycolytic capacity in muscle
– Less muscle glycogen
– Less glycolytic enzyme activity
– Blood lactate lower
– Mean and peak power increase with age
• Resting stores of ATP-PCr similar to adults’

Question 9

What are the endocrine responses to acute exercise in a child?

Answer 9

– Exercising growth hormone and insulin-like growth
factor surge higher than in adults
– increased Stress response to exercise compared to adults
– Hypoglycemic at exercise onset
– Immature liver glycogenolytic system

Question 10

What are substrate utilisation responses to acute exercise in a child?

Answer 10

– Relies more on fat oxidation compared to adults

– Exogenous glucose utilization high

Question 11

How do body weight & composition respond to physical training in a child?

Answer 11

– Respond to physical training similarly to adults
– Training - decreased body weight/fat mass, increased FFM
– Significant bone growth

Question 12

Is weight lifting safe for children to engage in?

Answer 12

• Weight lifting safe and beneficial
– Should be prescribed, supervised
– Low risk of injury
– Protects against injury
– Child: strength gains only via neural mechanisms,
no hypertrophy
– Adolescent: neural + hypertrophy

Question 13

Describe some changes in regards to aerobic training in children?

Answer 13

– Little or no change in V•O2max

– Performance increased due to improved running economy

Question 14

Describe some changes in regards to aerobic training in adolescents?

Answer 14

– More marked change in V•O2max

– Likely due to increase in heart size, SV

Question 15

What are some physiological responses to anaerobic training in a child?

Answer 15

– increased Resting PCr, ATP, glycogen
– increased Phosphofructokinase activity
– increased Maximal blood lactate

Question 16

Can adult anaerobic training programs be utilised to train a child?

Answer 16

• Adult anaerobic training programs can be
used with children and adolescents
– Be conservative to reduce risk of overtraining, injury,
loss of interest
– Explore variety of activities and sports

Question 17

What are the typical physical activity patterns among youth?

Answer 17

• Physical activity patterns established in
childhood carry into adulthood
• Intervention strategies aimed at getting
children more active have been mostly
ineffective

Question 18

Explain sports performance and specialisation in children/young adults?

Answer 18

• Sport performance in children and
adolescents improves with growth and
maturation
• Early specialization in one sport reduces
“fun” physical activities - reduced lifelong
physical activity

Question 19

Explain thermal stress in children?

Answer 19

– Children have a larger surface area:mass ratio
– decreased Evaporative heat loss (less sweat)
– Slower heat acclimation
– Greater conductive heat loss, gain
• More research needed; be conservative

Question 20

Explain a child’s growth when training?

Answer 20

– Little or no negative effect on height
– Affects weight, body composition with intensity
– Peak height velocity age unaffected
– Rate of skeletal maturation unaffected
• Maturation with training: effects on markers
of sexual maturation less clear

Question 21

Explain the chantes in height, weight and body composition in an aging person.

Answer 21

• Height decreases with age
– Starts at 35 to 40 years
– Compression of intervertebral discs
– Poor posture
– Later, osteopenia, osteoporosis
• Weight increases, then decreases
– increases 25 to 45 years: decreased physical activity, increased caloric intake
– decreases 65+ years: loss of body mass, less appetite
• Body fat content tends to increase
– Active versus sedentary older adults vary
– Older athletes have lower body fat content
– Older athletes have lower central adiposity
• Fat-free mass decreases starting around age 40
– decreased Muscle, bone mass
– Sarcopenia (protein synthesis decreases)
– Due (in part) to lack of activity
– decreased Growth hormone, insulin-like growth factor 1
• Bone mineral content decreases
– Bone resorption > bone synthesis
– Due to lack of weight-bearing exercise
• Body composition variables
– Body weight
– Percent body fat
– Fat mass
– Fat-free mass (FFM)

Question 22

How does training alter age-related body composition changes?

Answer 22

– decreased Weight, percent body fat, fat mass
– increased FFM (more likely with resistance training than with aerobic training)
– Men > women
• Biggest results with diet + exercise

Question 23

Describe the physiological responses to acute exercise in an aging person.

Answer 23

• Strength and neuromuscular function decrease
with age
– Interferes with activities of daily living
– Manifests ~50 to 60 years of age
– Results from decreased muscle mass
• Strength decrease offset by resistance exercise
• Type II fiber loss with aging
– Decrease in type II motor neurons
– Type I neurons innervate old type II fibers?
– Higher percent type I fibers
• Training slows or stops fiber-type change
• Size and number of muscle fibers decrease with
age
– Size of both type I and type II
– Lose 10% per decade after age 50
• Endurance training - no impact on decline
in muscle mass with age
• Resistance training - reduces muscle
atrophy, increased muscle cross-sectional area
• Reflexes slow with age
– Exercise preserves reflex response time
– Active older people ≈ young active people
• Motor unit activation decreases with age
– Exercise retains maximal recruitment of muscle
– Some studies show decreased strength due to local muscle (not neural) factors
• Exercise maintains muscle physiology
– Number of capillaries unchanged
– Oxidative enzyme activity only mildly reduced

Question 24

What are some CV responses to acute exercise in an aging person?

Answer 24

• Central and peripheral cardiovascular
decrements with age
• Reduced maximal HR
– Reduction varies considerably
– Electrical and receptor changes with age
– Same for active and sedentary people
• HRmax = [208 – (0.7 x age)]
• Maximal stroke volume (SV) decreases with age
– decreased Contractility, response to catecholamines
– Partial loss of Frank-Starling mechanism
– LV, arterial stiffening
– Exercise attenuates decline in SVmax
• V•O2max decreased with age due to decreased Q•max
– Due more to decreased HRmax, less to decreased SVmax
– Exercise attenuates decline in V•O2max
• Sedentary habits increase risk for vascular aging
– decreased Cardiac and arterial compliance
– Endothelial dysfunction
– Reduced vasodilation
• Exercise -> decreased risk
– Less arterial stiffening, endothelial dysfunction
– Preserved vasodilator signaling
– Research ongoing on proper exercise dose for
cardiovascular benefit
• Peripheral blood flow decreases with age
– ~10 to 15% reduction even with exercise
– Due to increased vasoconstriction, decreased vasodilation
– increased (a-v-)O2 difference compensates for decreased flow
• Effects of primary aging versus
cardiovascular deconditioning
– Which changes result from aging alone?
– Which changes result from reduced activity?

Question 25

What are some respiratory responses to acute exercise in an aging person?

Answer 25

• Respiratory function with sedentary aging – decreased Vital capacity and FEV1.0, increased residual volume, total lung capacity unchanged – Less air exchanged – decreased Lung and chest wall elasticity with age – But does not limit exercise capacity • Exercise maintains ventilatory capacity – Pulmonary ventilation does not limit aerobic capacity – Oxygen saturation remains high • V•O2max changes with aging – Measured in L/min or ml/kg/min? – Absolute versus relative decrement • V•O2max in normally active older people – Declines steadily from 25 years to 75 years – ~1% per year (~10% per decade) • V•O2max in older male athletes – 5 to 6% decline per decade in active adults – 3.6% decline over 25 years in elite athletes – 15% decline per decade in previously active adults • V•O2max in older female athletes – Fewer studies, but similar to men – ~1% decline per decade – Longitudinal changes > cross-sectional changes • Percent decline in V•O2max related to intensity of training before and during aging • Factors that affect rate of decline – Genetics – General activity level – Intensity and volume of training – Age-related body composition changes – Age range

Question 26

What are some changes in lactate threshold in response to acute exercise in an aging person?

Answer 26

• Lactate threshold (as % V•O2max) increases – Not predictive of running performance with aging – Percent V•O2max may not be best measure – Remember: absolute V•O2 decreases with age • Lactate threshold (as absolute V•O2) decreases

Question 27

What are the effects of resistance training on an aging person?

Answer 27

• Effects of resistance training on strength – increased Strength (men, women: 30%; some studies of men: 50-200+%) – Fiber hypertrophy – increased Cross-sectional area of types I, II – Neural adaptations • increased Muscle mass, muscle size, bone mineral density • Improved activities of daily living, decreased risk of falls

Question 28

What are VO2max improvements with training in an elderly population?

Answer 28

– Independent of sex, age, initial fitness – Young: increased maximal cardiac output (central) – Older: increased oxidative enzymes (peripheral)

Question 29

What are some anaerobic capacity changes with training in an elderly population?

Answer 29

– Less known than aerobic training results | – Lactate threshold bad predictor of performance

Question 30

Explain the changes of sports performance in an aging population.

Answer 30

• Running performance decreases with age. – Rate of decline independent of distance – Both 100 m, 10 km records slower with age – Decline accelerates past age 60. • Swimming performance decreases with age. – Decline accelerates past age 70. – Decline in women is greater than decline in men • Cycling performance – Peaks between 25 and 35 years – Speed then decreases by 0.7% per decade • Weight-lifting performance – Peaks between 25 and 35 years – Sum of power lifts then declines 1.8% per year

Question 31

Explain any special issues e.g. hyperthermia & the risks associated in an elderly population.

Answer 31

• Higher risk of death from hyperthermia – Higher core temperature than young subjects – Metabolic heat gain related to absolute V•O2 – Heat loss related to relative percent V•O2max • Physical training affects thermoregulation – Improves skin vasodilation (convection) – Improves sweat rate (evaporation) – Improves redistribution of cardiac output • Exercise in cold = increased risk of hypothermia – Risk not as great as hyperthermia – Reduced ability to generate metabolic heat – Excessive convective heat loss – Core temperature can drop even with mild cold stress • Must add behavioral thermoregulation • Exercise and longevity – Mild caloric restriction increases longevity – Exercise may contribute to caloric balance – Exercise - compression of mortality • Exercise can lead to injury – Tendon injury (rotator cuff, Achilles) – Cartilage injury (meniscus, focal injuries) – Stress fractures • Exercise can reduce risk of falls

Question 32

What is the difference between sex vs. gender?

Answer 32

``` • Sex is biologically determined. • Gender is culturally determined. • Most basic physiological comparisons to date have established sex differences. • IAAF policy on hyperandrogenism: Women must undergo testing if too “masculine.” ```

Question 33

In relation to body size and composition, what is the effect of testosterone?

Answer 33

• Testosterone leads to – increased Bone formation, larger bones – increased Protein synthesis, larger muscles – increased EPO secretion, increased red blood cell production

Question 34

In relation to body size and composition, what is the effect of estrogen?

Answer 34

``` • Estrogen leads to – increased Fat deposition (lipoprotein lipase) – Faster, more brief bone growth – Shorter stature, lower total body mass – increased Fat mass, percent body fat ```

Question 35

Explain body size and composition adaptations in females.

Answer 35

• Distinct female fat deposition pattern • Rapid storage on hips and thighs due to increased lipoprotein lipase activity • decreased Lipolytic activity makes regional fat loss more difficult • Lipoprotein lipase decreases, lipolysis increases during third trimester of pregnancy, lactation

Question 36

How does muscle strength differ between sexes?

Answer 36

– Upper body: women 40 to 60% weaker – Lower body: women 25 to 30% weaker – Due to total muscle mass difference, not difference in innate muscle mechanisms • No sex strength disparity when expressed per unit of muscle cross-sectional area

Question 37

What are the causes of upper body strength disparity?

Answer 37

``` – Women have more muscle mass in lower body – Women utilize lower body strength more – Altered neuromuscular mechanisms? • Women: smaller cross-sectional areas • Similar fiber-type distribution • Research indicates women more fatigue resistant ```

Question 38

How does cardiovascular function differ between the genders?

Answer 38

• For same absolute submaximal workload – Same cardiac output – Women: lower stroke volume, higher HR (compensatory) – Smaller hearts, lower blood volume • For same relative submaximal workload – Women: HR slightly higher , SV lower, cardiac output lower – Leads to decreased O2 consumption • Women compensate for decreased hemoglobin via increased (a-v-)O2 difference (at submaximal intensity) – (a-v-)O2 difference ultimately limited, too – Lower hemoglobin, lower oxidative potential

Question 39

What are some sex differences in terms of respiratory function?

Answer 39

– Due to difference in lung volume, body size – Similar breathing frequency at same relative workload – Women increase frequency at same absolute workload • Women’s V•O2max < men’s V•O2max • Untrained sex comparison unfair – Relatively sedentary nonathlete women – Relatively active nonathlete men • Trained sex comparison better – Similar level of condition between sexes – May reveal more true sex-specific differences • Can scale V•O2max to other body variables – Height, weight, FFM, limb volume – Sex difference minimized or gone with scaling • Simulated women’s fat mass on men – Reduced sex differences in treadmill time, submaximal V•O2(ml / kg), V•O2max – Women’s additional body fat major determinant of sex-specific difference in metabolic responses • Women’s lower hemoglobin limits V•O2max • Women’s lower cardiac output limits V•O2max – SVmax limited by heart size, plasma volume – Plasma volume loading in women helps – Submaximal absolute V•O2: no sex difference in SV • Sex differences in lactate, threshold – Peak lactate concentrations lower in women – Lactate threshold occurs at same percent V•O2max

Question 40

What are some changes in body composition between the sexes?

Answer 40

• Body composition changes – Same in men and women – decreased Total body mass, fat mass, percent body fat – increased FFM (more with strength vs. endurance training) • Weight-bearing exercise maintains bone mineral density • Connective tissue injury not related to sex

Question 41

Explain strength gains in women vs. men?

Answer 41

– Less hypertrophy in women versus men, though some studies show similar gains with training – Neural mechanisms more important for women • Variations in weight lifted for equivalent body weight – For given body weight, trained men have more FFM than trained women – Fewer trained women – Factors other than FFM?

Question 42

Explain cardiorespiratory changes in the sexes? Are these changes sex-specific?

Answer 42

• Cardiorespiratory changes not sex specific • Aerobic, maximal intensity – increased Q•max due to increased SVmax (increased preload, contractility) – increased Muscle blood flow, capillary density – increased Maximal ventilation • Aerobic, submaximal intensity – Q• unchanged – increased SV, decreased HR

Question 43

Explain VO2max changes between the sexes? Are these changes sex-specific?

Answer 43

• V•O2max changes not sex specific – ~15 to 20% increase – increased Q•max, increased muscle blood flow – Depends on training intensity, duration, frequency • Lactate threshold increased • Blood lactate for given work rate decreases • Women respond to training like men do

Question 44

Explain sports performance differences between the sexes.

Answer 44

``` • Men outperform women by all objective standards of competition – Most noticeable in upper-body events – Gap narrowing • Women’s performance drastically improved over last 30 to 40 years – Leveling off now – Due to harder training ```

Question 45

Explain menstruation and athletic performance in females?

Answer 45

• Normal menstrual function – Menstrual (flow) phase – Proliferative phase (estrogen) – Ovulation—follicle stimulating hormone (FSH), luteinizing hormone (LH) – Secretory phase (estrogen, progesterone) • Cycle length ~28 days, can vary • No reliable data indicate altered athletic performance across menstrual phases • No physiological differences in exercise responses across menstrual phases • World records set by women during every menstrual phase

Question 46

Explain menstrual dysfunction and athletic performance in females?

Answer 46

``` • Menarche: first menstrual period – May be delayed in certain sports (e.g., gymnastics) – Delayed menarche: after age 14 • Delayed-menarche athletes self-select? – Sport may not - delayed menarche – Small, lean athletic girls (delayed menarche candidates) may gravitate to sport • Menstrual dysfunction – Seen more in lean-physique sports – Eumenorrhea: normal – Oligomenorrhea: irregular – Amenorrhea (primary, secondary): absent – Can affect 5 to 66% of athletes • Menstrual dysfunction ≠ infertility • Secondary amenorrhea—caused by energy deficit (inadequate caloric intake) – decreased LH pulse frequency – decreased T3 secretion – decreased Estrogen, progesterone – May also involve GnRH, leptin, cortisol • As long as caloric intake adequate, exercise does not lead to secondary amenorrhea ```

Question 47

Explain any pregnancy concerns?

Answer 47

1. Acute reduction in uterine blood flow (shunt to active muscle) -> fetal hypoxia 2. Fetal hyperthermia from increase in maternal core temperature 3. Maternal CHO usage increased, thereby decreasing CHO availability to fetus 4. Miscarriage, final outcome of pregnancy • decreased Uterine blood flow may not lead to hypoxia – Uterine (a-v-)O2 difference increase may compensate – Fetal HR increases due to maternal catecholamines • Fetal hyperthermia: unresolved • CHO availability: unresolved • Miscarriage, final pregnancy outcome – Data scarce, conflicting – Many studies show favorable (or no) effects

Question 48

Explain physical activity recommendations for pregnant women?

Answer 48

• Mild-to-moderate exercise 3 times / week • No supine exercise after first trimester • Stop when fatigued • Non–weight-bearing exercise preferable • No risk of falling, loss of balance, etc. • Ensure adequate caloric intake • Dress and hydrate to avoid heat stress • Prepregnancy exercise routine should be gradually resumed postpartum • No scuba diving • Benefits > risks if cautiously undertaken

Question 49

Explain osteopenia & osteoporosis and how hormone deficiencies contribute to these diseases (risk factors between the sexes?)

Answer 49

``` • Osteopenia versus osteoporosis – Risk greater in women especially after menopause – Slowed and retarded by weight-bearing exercise • Major contributing factors – Estrogen deficiency – Inadequate calcium intake – Inadequate physical activity – Amenorrhea, anorexia nervosa • Physical activity affects bone health – Maximize bone density early in life – Diet, weight-bearing physical activity • Menstrual status affects bone health – Particular concern for postmenopausal women; exercise can protect against bone loss – Women with amenorrhea or anorexia nervosa often suffer low bone mass ```

Question 50

Explain eating disorders and risk factors between the sexes.

Answer 50

• Anorexia nervosa – Refusal to maintain minimal normal weight – Distorted body image, fear of fatness – Amenorrhea • Bulimia nervosa – Recurrent binge eating – Lack of control during binges – Purging behaviors (vomiting, laxatives, diuretics) • Young women at highest risk • Eating disorder versus disordered eating • Worse in certain sports – Appearance sports: diving, figure skating, ballet – Endurance sports: distance running, swimming – Weight-class sports: jockeys, boxing, wrestling – Perfectionists, competitive, under tight control • Self-reporting underestimates prevalence • Eating disorders considered addictions – Behavior reinforced by media, parents, coaches – Very difficult to treat – Often accompanied by denial – Life threatening, expensive to treat • Must seek out trained clinical specialist

Question 51

What is the Female Athlete Triad?

Answer 51

• Syndrome of interrelated conditions – Energy deficit  secondary amenorrhea  low bone mass – Disordered eating may (not) be involved • Three disorders can occur alone or in combination, must be addressed early • Treatment: increased caloric intake, decreased activity (in some cases)

Question 52

What is menopause & how can exercise be utilised for this condition?

Answer 52

• Usually occurs between ages 45 and 55 • Symptoms can lower quality of life in some • Exercise is recommended to improve mood, decrease depression, and improve sleep