Guest lecturer - Sex differences Flashcards
why are most studies on exercise physiology only on __________ ________?
- only on young recreationally active men
- bc women have too many variabilities/confounding variables! hormone fluctuations (basically 4 different people in a month) –> hard to investigate science
what is one big misconception about male vs female in exercise physiology?
that females are just smaller males
what do we already know about inherent differences between males and females?
MALES have
- less body fat
- bigger shoulder width
- more total lean mass
- more strength
- more Hg mass
- faster running, swimming and cycling speed
- more lung surface
- better weightlifting, powerlifting
- better grip, bicep strength
- more power
etc.
define
- glycemic control –> def + how?
- insulin sensitivity
GLYCEMIC CONTROL
- ability to maintain blood glucose homeostasis in response to stimuli like meals with carbohydrates
- regulation of blood glucose homeostasis = balance btw haptic glucose production and peripheral glucose uptake
INSULIN SENSITIVITY:
- cell’s sensitivity to insulin secretion to get glucose absorbed into cell
compare healthy vs impaired glucose tolerance person when eating meals and going through their day
- consequence of impaired person?
- healthy: will have peaks and lows, if there’s a high, rapidly comes down
- impaired: really big peaks and really big lows, not super consistent
CONSEQUENCE: if sugar stays in blood too long –> leads to chronic metabolic diseases
what are 4 ways to measure glycemic control?
- blood sample –> check [glucose]
- continuous glucose monitoring –> measure in free living setting
- oral glucose tolerance test –> give 75g and measure blood glucose every hour for 3h ish
- hyperinsulinemic … (don’t worry about it)
what are the acute exercise effects on glucose uptake and insulin sensitivity? (graph)
- vs chronic exercise effects
ACUTE:
- phase 1: during exercise: increase glucose uptake bc increased blood flow + muscle contraction (mechanical stimuli) mediates glucose uptake in muscles
- phase 2: after exercises (up to 2 days): transient increase in insulin sensitivity –> ie only need 5 units of insulin vs 10 units to have same effect
CHRONIC:
- alternate between high glucose uptake and high insulin sensitivity –> for several days/week
- eventually long-lasting adaptations will be made –> insulin sensitivity baseline will become higher and will increase less after each exercise
- peripheral adaptation: increase glycemic control and increase insulin sensitivity!
what are 3 common types of aerobic exercise?
- MODERATE-INTENSITY CONTINUOUS TRAINING (MICT):
- 30-90min at moderate intensity (65% VO2max) - HIGH-INTENSITY INTERVAL TRAINING (HIIT):
- ie 10 x 1min @90% max HR, 1 min recovery
- anaerobic metabolism –> uses glucose - SPRINT INTERVAL TRAINING (SIT):
- 3 x 20” all out sprints –> 2 min recovery
*2 and 3: are very time efficient way to get the same benefits as 1
describe the energy substrate us btw rest, 40%, 55% and 75% of VO2 max exercise
REST:
- 50% plasma FFA, 50% plasma glucose
40%:
- 35% ish muscle glycogen
- 35% ish plasma FFA
- other fat sources (20% ish)
- plasma glucose (10%)
55%:
- 40% muscle glycogen
- 25% plasma FFA
- 25% other fat sources
- 20% plasma glucose
75%:
- 58% muscle glycogen
- 19% plasma glucose
- 19% ish plasma FFA
- 5% ish other fat sources
difference btw sex and gender?
- why is understanding sex differences in metabolism important?
sex = biologically determined
- assigned at birth, based on reproductive organ and chromosome
gender is socially or culturally determined
- how one identifies
- important for optimizing health, performance and personalized interventions
what do studies show about:
1. mean insulin sensitivity in males vs females (study where they weren’t trying to find sex dif)
2. change in insulin AUC males vs females after 16 months of MICT in obese
3. insulin sensitivity in healthy males vs females after 6 weeks SIT
4. 24h avg glu in males vs females overweight after 6 weeks of SIT
5. insulin sensitivity in females with obesity after 6 weeks HIIT
- mean insulin sensitivity increased by 10% but high variability –> men had 16% and women had 5% improvements
- lower/improved insulinemia for males (35% improved) but not in females (no change btw control and exercise, a bit of decrease actually)
- 30% improvement for males, no improvement/decrease in females
- males improved, but females did a bit worse
- did NOT improve insulin sensitivity at all
what were the different ways of measuring glycemic control/insulin sensitivity in the 5 studies?
- intravenous glucose tolerance test
- oral glucose tolerance test
- intravenous glucose tolerance test
- continuous glucose monitoring
- oral glucose tolerance test
what are the sex differences in skeletal muscle metabolism during acute exercise? (7)
- decreased RER in females in prolonged exercise
- women tend to rely more on fat (RER closer to 0.7) VS males rely more on CHO (RER closer to 1.0) - decreased expression of enzymes needed for glucose metabolism (hexokinase, glycogen phosphorylase, PFK, lactate dehydrogenase, glycogen synthase) in females –> explains why they have a decreased reliance on CHO in exercise
- females use less muscle glycogen during exercise vs men, regardless of exercise intensity
- in both type I and type II fibers –> men have a greater decrease in muscle glycogen - females have greater type 1 muscle fibers (slow twitch, oxidative) VS males have greater type 2a and 2x fibers
- females have greater capillary density in all fibers = greater aerobic capacity
- less AMPK signalling in females (barely 10%) vs males (300% increase in signaling after 90’ exercise)
- AMPK signaling = stress response needed to adaptation! - females have less ADP, AMP, Cr, ATP reduction, lactate, catecholamine than males (related to AMPK activation)
- catecholamine reflects high cellular stress = anaerobic glycolysis
what does glycogen breakdown have to do with insulin sensitivity?
- consequence for females?
- when there is glycogen breakdown, your body will want to have post-exercise re-synthesis = increase glycogen synthase activity –> increase demande in glucose uptake = increased carbohydrate storage –> related to insulin sensitivity!
VS females –> decreased glycogen breakdown –> decrease post-exercise glycogen re-synthesis = decrease demand for glucose uptake
are physiological differences btw males and females due to estrogen?
- study: 8 days supplementation of estrogen in men –> showed that decrease glucose oxidation and increased fat oxidation
- therefore, estrogen has a direct effect on energy metabolism
- ie look at post-menopausal (similar hormonal profile to males) –> no more sex-differences
