cho metabolism during prolonged exercise (~72% vo 2max ) to exhaustion w/ and w/out cho feedings...
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CHO metabolism during prolonged exercise (~72% VO2max) to exhaustion w/ and w/out CHO feedings (every 20 min)
Coyle et al., JAP, 1986
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Fat metabolism during prolonged exercise
(~72% VO2max) to exhaustion w/ and
w/out CHO feedings (every 20 min)
1 hr 2 hr 3 hr 4 hrPlacebo .85 .84 .80 --
CHO .85 .86 .86 .85
RER data
Coyle et al., JAP, 1986
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Substrate use during exercise to exhaustion w/ and w/out CHO feeding
Coyle et al., JAP, 1986
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Fluid & CHO Intake during Exercise
water (placebo) 5% glucose polymer 6% glucose/sucrose solution 7% glucose polymer/fructose
Murray et al., MSSE, 1987
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CHO and fluid feeding during intermittent exercise
no difference for plasma Na+ or K+
no difference in RPE no difference in RER no difference in plasma La no difference in Power 1 (240 revolutions) time of Power 2 (480 revolutions) shorter for
sucrose/glucose and glucose polymer/fructose trials
most complaints with glucose polymer trial
Murray et al., MSSE, 1987
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Hepatic glucose output (HGP) and glucose
uptake (Rd) w/ and w/out CHO feedings during
prolonged exercise (~70% of VO2max)
McConell et al., JAP, 1994
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CHO Feeding during Prolonged Exercise
blood glucose maintains CHO oxidation rate time to exhaustion/performance conserves liver glycogen muscle glucose uptake plasma insulin plasma FFA no effect on muscle glycogen utilization (in
cycling studies)
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CHO feeding during prolonged exercise
time of CHO feeding few differences in CHO type upper limit of exogenous CHO oxidation difference in CHO oxidation between
running and cycling protocols?
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Early studies on diet and performance
high-fat diet RER and RPE (Krogh & Lindhard, 1920)
correlation between blood [glucose] and physical condition at end of Boston Marathon (Levine et al., 1924)
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Bergström et al., Acta Physiol Scand, 1967
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Bergström & Hultman, Scand J Clin Lab Invest, 1967
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Benefits of CHO Loading
muscle glycogen stores time to exhaustion no benefit on performance of <90 min
(Hawley et al., 1997; Madsen et al., 1990)
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Effects of High-CHO Diet
time to exhaustion muscle glycogen stores use of CHO for energy
Effects of High-fat Diet
plasma [FFA] and FFA uptake IMTG use of fat (70% from IMTG) for energy ß-oxidation enzymes
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Hawley et al., J Sports Sci, 1995
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Point 5: A high-CHO diet maximizes performances during training(TD Noakes, MSSE, 1997)
Athletes do not each high-CHO diets during training.
Literature doesn’t support that dietary-CHO during training diminishes training or performance (Lamb et al., 1990; Sherman & Wimer, 1991; Simonsen et al., 1991).
Studies have shown that a period of adaptation to low-CHO diet may improve subsequent performance (Lambert et al., 1994; Muoio et al., 1994)
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Effect of High-Fat Diet
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Early Studies of Diet Effects
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Effect of Dietary CHO in Untrained Subjects
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Effect of CHO intake on muscle glycogen and rowing power (3x2500 m)
Simonsen et al., JAP, 1991
** Week 4 was significantly greater than low-CHO diet group
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Effect of Dietary CHO on Muscle Glycogen Repletion
Costill & Miller, Int J Sports Med, 1980
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Sport Nutrition: Carbohydrate
Before exercise CHO intake helps “top off” glycogen storesDuring exercise CHO intake not important until later in
exercise (but before onset of fatigue)After exercise high CHO intake increases rate of glycogen
storage – CHO type doesn’t matter