Formal, J. R., Jackson, C. G., Anderson, T. R., & Greer, F. A. (2012). Effects of chocolate milk and a whey protein drink on muscle damage and performance. Presentation 1854 at the 59th Annual Meeting of the American College of Sports Medicine, San Francisco, California; May 29-June 2, 2012.

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This study compared muscle recovery effects of fat-free chocolate milk and a chocolate whey protein drink mixture on performance and measures of muscle damage in male recreational athletes (N = 8). Ss completed three testing sessions after muscle damage, measured by elevated serum creatine kinase levels, that was induced by a sprint protocol. On day one of each testing session, a standardized warm-up was followed by 15 x 30-meter sprints with a 10-meter deceleration zone leading to a complete stop with 60 second rest periods. Creatine kinase and performance assessments [peak quadriceps isometric force, vertical jump, pro agility, muscle soreness, and Mental and Physical State and Trait Energy and Fatigue Scales] were measured immediately after and at 48 and 96 hours post-exercising. Testing session 1 established baseline measures with no supplementation. In testing sessions 2 and 3, Ss received two cups of either fat-free chocolate milk or chocolate whey protein drink post-exercise. Treatment beverages were isocaloric and given in a randomly counterbalanced double-blind protocol.

There were no significant differences in sprint performances across tests, indicating no training effect over time. Creatine kinase levels were clinically elevated above normal range immediately following all sprint protocols indicating exercise-induced muscle damage. Creatine kinase levels were highest 48 hours post-exercise and lowest 96 hours post-exercise. When creatine kinase levels at 48 and 96 hours were compared, the fat-free chocolate milk levels were significantly lower than those of the chocolate whey protein drink condition. There were no differences between the supplements for the peak quadriceps isometric force, vertical jump, pro agility, muscle soreness, and Mental and Physical State and Trait Energy and Fatigue Scales assessments.

Implication. Fat-free chocolate milk attenuates elevated creatine kinase levels following exercise-induced muscle damage faster at 48 and 96 hours than a chocolate whey protein drink mixture. Also cellular level muscle recovery was enhanced by fat-free chocolate milk. Fat-free chocolate milk may therefore lessen exercise induced muscle damage if used chronically as a post-exercise drink. Performance variables were not affected differentially by either supplement.

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