Comparison of Carbohydrate and Milk-Based Beverages on Muscle Damage and Glycogen Following Exercise

in International Journal of Sport Nutrition and Exercise Metabolism
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This study examined effects of carbohydrate (CHO), milk-based carbohydrate-protein (CHO-PRO), or placebo (P) beverages on glycogen resynthesis, muscle damage, inflammation, and muscle function following eccentric resistance exercise. Untrained males performed a cycling exercise to reduce muscle glycogen 12 hours prior to performance of 100 eccentric quadriceps contractions at 120% of 1-RM (day 1) and drank CHO (n = 8), CHO-PRO (n = 9; 5 kcal/kg), or P (n = 9) immediately and 2 hours post-exercise. At 3 hours post-eccentric exercise, serum insulin was four times higher for CHO-PRO and CHO than P (p < .05). Serum creatine kinase (CK) increased for all groups in the 6 hours post-eccentric exercise (p < .01), with the increase tending to be lowest for CHO-PRO (p < .08) during this period. Glycogen was low post-exercise (33 ± 3.7 mmol/kg ww), increased 225% at 24 hours, and tripled by 72 hours, with no group differences. The eccentric exercise increased muscle protein breakdown as indicated by urinary 3-methylhistidine and increased IL-6 with no effect of beverage. Quadriceps isokinetic peak torque was depressed similarly for all groups by 24% 24 hours post-exercise and remained 21 % lower at 72 hours (p < .01). In summary, there were no influences of any post-exercise beverage on muscle glycogen replacement, inflammation, or muscle function.

J.R. Wojcik and J. Walberg-Rankin are with the Department of Human Nutrition, Foods, and Exercise at Virginia Polytechnic Institute and State University, Blacksburg, VA 24061. L.L. Smith is with the Department of Exercise Science at Northeastern Illinois University, Chicago, IL 60625. F.C. Gwazdauskas is with the Department of Dairy Science at Virginia Polytechnic Institute and State University, Blacksburg, VA 24061.