Ferguson-Stegall, L., McCleave, E. L., Ding, Z., Doerner, P. G., Liu, Y., Wang, B., Dessard, B. M., Kleinart, M., Healy, M., Lassiter, D. G., & Ivy, J. L. (2011). Aerobic exercise training adaptations are increased by post-exercise carbohydrate-protein supplementation. Medicine and Science in Sports and Exercise, 43(5). Supplement abstract 2214.

This study compared the effects of a carbohydrate-protein supplement in the form of chocolate milk, an isocaloric carbohydrate supplement, and placebo on cardiovascular and intramuscular adaptations that occurred in response to a 4.5 week aerobic exercise training program in healthy, untrained mixed-gender Ss (N = 32). Ss cycled for one hour, five days per week, for four and a half weeks at 75-80% of maximal oxygen consumption (VO2max). Supplements were ingested immediately and one hour after all sessions. VO2max and lactate threshold were assessed at baseline, the midpoint of training, and the end of the training period. Muscle biopsies were performed at baseline, midpoint, and the end of the training period to assess changes in citrate synthase and succinate dehydrogenase activity, as well as for total PGC-la(alpha) (a master regulator of mitochondrial biogenesis) content.

Improvements in VO2max were significantly greater in the chocolate milk group than the carbohydrate and placebo groups. Lactate threshold increased in all groups from baseline to the study-end with no differences between treatments. Total increases from baseline to the study-end in the activities of citrate synthase and succinate dehydrogenase, as well as in total PGC-la content were found in all groups over time, with no significant differences between treatments.

Implication. VO2max improvements occur faster with chocolate milk supplementation than with carbohydrate or placebo. The faster rate of adaptation is systemic rather than cellular in nature.

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