Flashcards in Bergdahl- Chapter 30 and 31 Deck (50):
in general, what percentage of people are obese ?
who tends to gain the most weight ?
how much of the risk of becoming obese depends on genetic factors ?
so do genes cause obesity ?
no, they instead lower the threshold for its development in a more susceptible environment
what genetic factor can be linked to obesity ?
congenital absence of leptin produced continual hunger and marked obesity in studies
what is leptin
a hormonal body weight-regulating substance produced by fat and released into the bloodstream that acts on the hypothalamus
what is the recommended amount of physical activity / day ?
what are the 5 specific risks of excessive body fat ?
1) impaired cardiac function from increased mechanical work
2) hypertension, stroke, DVT
3) increased insulin resistance, type II diabetes
4) renal disease
5) sleep apnea, pulmonary disease (due to added effort to move chest wall)
what are the three ways to measure fat ?
1) percentage of body mass composed of fat
2) distribution of fat in different anatomic regions
3) size and number of individual fat cells
what is the standard fat percentage for overfatness in men and women ?
men: over 20%
women: over 30%
what waist-to-hip girth ratios increase risk of death ?
women : 0.8
what is central/ android-type obesity ?
fat deposits in abdominal area, internal visceral deposits
greater health risk
what are the two ways adipose tissue mass increases ?
1) fat cell hypertrophy
2) fat cell hyperplasia (number)
when you lose weight, what happens in the adipose tissue ?
shrinkage of adipocytes with no change in cell number
when you gain weight, what happens in the adipose tissue ?
enlarges existing adipocytes
what is the best way to weight control ?
following the 1st law of thermodynamics (weight loss occurs whenever energy output exceeds energy intake, regardless of macronutrient mixture)- a healthy diet, moderately reduced food intake
what brain area controls our level of weight/body fat within a tight range ?
how can exercise control the hypothalamus differently than diet ?
exercise and drugs can change a person's setpoint, but dieting has no effect. in dieting, everytime body weight decreases below the certain setpoint, there are internal adjustments that resist the change to conserve and replenish body fat
what is the biologic feedback mechanism that makes it hard to lose weight ?
when fat people lose weight, adipocytes increase their level of fat-storing enzyme, which facilitates body fat synthesis, and the fatter the person, the greater the production of the enzyme LPL
what are ketogenic diets and why are they bad ?
carb restriction while ignoring total calories (limit to 20g/day)
- this generates excess plasma ketone bodies, acidosis since fat is being used more as an energy source
- this aggravates kidneys, depletes glycogen reserves, causes dehydration, etc
what are high protein diets and why are they bad ?
can strain liver, create electrolyte imbalance, glycogen depletion, lean tissue loss
what are semistarvation diets ?
low cal that may benefit several clinical obesity in a very controlled setting
400-800 kcal daily
how does hydration level affect weight control
70% of weight lost in first week is water loss
then water loss lessens while body fat loss increases from 25 to 70%
how does duration of energy deficit affect weight control
caloric equivalent of weight loss increases when duration of caloric restriction progresses
after 2 months it's 2x what it was in the first week
does excess weight gain parallel reduced physical activity or increased caloric intake ?
reduced physical activity
what is the contribution of recovery metabolism to total energy expenditure in low to moderate exercise ?
very small relative to exercise energy expenditure (75 kcal)
what is the dose-response relationship between the total energy expenditure in physical activity and effectiveness of exercise for weight loss ?
focus on increasing duration not intensity for physical activity in order to up total expenditure
energy cost relates directly to body mass- overweight person will expend more calories
does increase in a muscle's metabolic activity stimulate relatively greater fat mobilization in that area ?
nope. spot reduction is not a thing
decreases in body fat will rid itself of which fat ? rather than which one ?
upper body subcutaneous and deep abdominal fat
rather than more resistant fat in legs (gluteal and femoral)
which gender responds more favorably to effects of exercise on weight loss ? why ? 3 reasons
1) gender different in body fat distribution
2) women may more effectively preserve energy balance with increased physical activity
3) men reduce energy intake with exercise training more than women do (they eat more with training)
what kind of aerobic fitness prescription is recommended for the elderly ?
lower level of intensity
what is a priority in terms of exercise for the elderly ?
joint flexibility and balance to reduce risks of falls
when are people the strongest ? why ?
at ages 20-40, that's when the muscle CSA is the biggest
how does the capacity for power decline compared to the capacity for strength ? eccentric and concentric ? arm and leg ?
power declines faster
eccentric declines earlier
arm declines slower
what are the consequences of motor unit remodeling in age ?
denervation, muscle atrophy
how do older men improve compared to older women ?
they'll have greater absolute gains but relative percentage improvement is the same
how does aging affect neural function ?
40% decline in spinal cord axons number
10% decline in NCV
decrement in neuromuscular performance
how does glucose change in aging ?
impaired glucose tolerance, leading to type II diabetes
how is metabolic function affected by aging ?
pituitary gland decreases release of thyrotropin
how does GH release change in aging ?
how does dehydroepiandrosterone release change in aging ?
decreases output from adrenal cortex
which axis is changed in aging leading to menopause and andropause ?
hypothalamic-pituitary - gonadal
how does aging affect static and dynamic lung function ?
how does pulmonary ventilation and gas exchange kinetics change in aging ?
what is the rate at which VO2 max declines ?
1% per year
can regular aerobic exercise prevent the age related decline in aerobic power ?
how does MHR change with age ?
how does max CO change with age ? due to which factors ?
decreases due to lower max HR and SV
how does compliance change with age ?