and now a contest: why women live longer than men
TRANSCRIPT
Physiological responses to heat accumulation
surface blood flow is increased at expense to other tissues
EPI release– HR upward drift glycogen use
blood volume cardiac efficiency ( SV, HR)
fatigue
Fluid balance
dehydration impairs endurance performance, – minimal effect on power and speed events
blood volume will skin blood flow and heat dissipation
thirst mechanism doesn’t keep up with dehydration
need for water replacement > than electrolyte replacement
Maintaining fluid balance
fluid intake during exercise will:– minimize dehydration– minimize rise in body temperature– reduce CV stress
[CHO] > 6-8% slows absorption from gut
Sport Nutrition: Sport Drinks
[CHO] affects fluid absorption rate in gut– Gatorade – 6%– Exceed – 7.2%– Coca-Cola – ~11%– Sprite – 10.2%– cranberry juice – 15%– orange juice – 11.8%
ACSM Fluid Replacement Recommendations
Before exercise, drink: – ~500 ml 2 hr before exercise
During exercise, drink:– early and at regular intervals– to replace lost fluids (if tolerated)– over-hydration can result in hyponatremia
After exercise, drink:– excess of that lost during exercise
Acclimatization to exercise in heat
body fluids/blood volume (w/in 3-5 d) skin blood flow rate of sweating (may take up to 10 d) electrolyte loss heat tolerance
Achieving heat acclimatization normal workouts in heat for 5-10 d
Suggested Readings(available at gssiweb.com under Sport Science Exchange)
Murray, R. Fluid replacement: The American College of Sports Medicine Position Stand. GSSE 9(4) SSE#53, 1996. http://www.gssiweb.com
Maughan, R.J. and S.M. Shirreff. Preparing athletes for competition in the heat: developing an effective acclimatization strategy. GSSE 10(2) SSE#65, 1997.http://www.gssiweb.com
The primary mode of heat dissipation during exercise is
a. convection
b. radiation
c. conduction
d. sweat evaporation
What likely is the primary cause of HR drift during moderate-intensity exercise in heat?
a. plasma volume leading to SV
b. Epi release
c. temperature
d. sweating
e. body weight