MIXED CARBOHYDRATE SUPPLEMENTATION INCREASES CARBOHYDRATE OXIDATION AND ENDURANCE EXERCISE PERFORMANCE AND ATTENUATES POTASSIUM ACCUMULATION

We studied the effects of different CHO supplements on exercise metabo lism (1 hr at 75% VO(2)max) and performance (fatigue time at 85% VO(2) max) in 8 male endurance athletes (VO(2)max = 68.8 +/- 3.8 ml . k(-1). min(-1)). Four treatments were administered in a randomized, double-b lind fashion: Trial A = 3-day pretest, postexercise supplementation (1 77 kcal [81% carbohydrate, 19% protein] consumed < 10 min after exerci se) + 600 ml 8% glucose polymers/ fructose 1 hr pretesting + 600 ml 8% glucose polymers/glucose during testing; Trial B = placebo during 3-d ay pretest + remainder same as Trial A; Trial C = placebo at all time points; and Trial D = same as Trial B with 8% glucose 1 hr before the test as well as during the test. Time to fatigue at 85% VO(2)max (up a rrow 24%) and total CHO oxidation were greater for A versus C (p < .05 ). Plasma glucose concentration was higher for A and B versus C, while increases in plasma potassium concentration were attenuated for A ver sus C (both p < .05). None of the supplements had differential effects upon hematocrit, plasma sodium [Na+] and lactate, VO2, or rating of p erceived exertion during exercise. Three-day preexercise protein + car bohydrate supplements followed by 1-hr pre- and during-exercise mixed carbohydrate supplements increased time to fatigue and carbohydrate ox idation and attenuated rises in plasma [K+] compared to placebo.