Carbohydrate Supplementation Attenuates Muscle Glycogen Loss during Acute Bouts of Resistance Exercise

in International Journal of Sport Nutrition and Exercise Metabolism
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The effects of carbohydrate (CHO) supplementation on muscle glycogen and resistance exercise performance were examined with eight highly resistance trained males (mean ± SEM, age: 24.3 ± 1.1 years, height: 171.9±2.0 cm, body mass: 85.7 ± 3.5 kg; experience 9.9 ± 2.0 years). Subjects participated in a randomized, double blind protocol with testing sessions separated by 7 days. Testing consisted of an initial isokinetic leg exercise before and after an isotonic resistance exercise (IRT) session consisting of 3 leg exercises lasting ~39 min. Subjects consumed a CHO (1.0 g CHO ·kg body mass−1) or placebo treatment (PLC), prior to and every 10-min (0.5 g CHO ·kg body mass−1) during the IRT. Muscle tissue was obtained from the m vastus lateralis after a supine rest (REST) immediately after the initial isokinetic test (POST-ISO) and immediately after the IRT (POST-IRT). The CHO treatment elicited significantly less muscle glycogen degradation from the POST-ISO to POST-IRT (126.9 ± 6.5 to 109.7 ± 7.1 mmol·kg wet weight−1) compared to PLC (121.4±8.1 to 88.3±6.0 mmol·kg wet weight−1). There were no differences in isokinetic performance between the treatments. The results of this investigation indicate that the consumption of a CHO beverage can attenuate the decrease in muscle glycogen associated with isotonic resistance exercise but does not enhance the performance of isokinetic leg exercise.

G.G. Haff is with the Exercise Physiology Laboratory at Appalachian State University, Boone NC 28608. A.J. Koch, J.A. Potteiger, K.E. Kuphal, and J.J. Jakicic are with the Exercise Physiology Laboratory at the University of Kansas, Lawrence, KS 66045. L.M. Magee is with the Watkins Health Center at the University of Kansas, Lawrence, KS 66045. S.B. Green is with the Department of Psychology and Research in Education at the University of Kansas.