Chocolate milk is an effective postexercise drink that improves recovery, according to the results of a small, randomized trial reported in the February issue of the International Journal of Sport Nutrition and Exercise Metabolism. "Our study indicates that chocolate milk is a strong alternative to other commercial sports drinks in helping athletes recover from strenuous, energy-depleting exercise," coauthor Joel M. Stager, PhD, from Indiana University in Bloomington, said in a news release. "Chocolate milk contains an optimal carbohydrate to protein ratio, which is critical for helping refuel tired muscles after strenuous exercise and can enable athletes to exercise at a high intensity during subsequent workouts."
On 3 separate days, 9 male, endurance-trained cyclists performed an interval workout followed by 4 hours of recovery, and a subsequent endurance trial to exhaustion at 70% maximum oxygen consumption (VO2max). In a single-blind, randomized design, the men drank equivalent volumes of chocolate milk, fluid replacement drink (FR), or carbohydrate replacement drink (CR) immediately after the first exercise bout and 2 hours of recovery. The chocolate milk and CR had equivalent carbohydrate content. Primary endpoints were time to exhaustion, average heart rate, rating of perceived exertion, and total work for the endurance exercise.
Time to exhaustion and total work were significantly greater for chocolate milk and for FR trials than for CR trials, suggesting that chocolate milk is an effective recovery aid between 2 exhausting exercise bouts.
Study limitations include the possibility that the 4-hour recovery period limited the complete digestion of the complex carbohydrates contained in CR. "The results of this study suggest that chocolate milk, with its high carbohydrate and protein content, may be considered an effective alternative to commercial FR and CR for recovery from exhausting, glycogen-depleting exercise," the authors write.
According to the authors, the amount of stored glycogen in skeletal muscles influences exercise performance, and delaying carbohydrate ingestion for 2 hours after a workout can reduce the rate of glycogen resynthesis by half. Studies noted by the authors have suggested that 50 to 75 g of carbohydrate be ingested within 30 to 45 minutes after exercise, with ingestion of 1.2 to 1.5 g carbohydrate per kilogram of body weight per hour for the next few hours. Protein ingestion also has been shown to hasten the rate of glycogen synthesis. CR and FR, which replenish fluid and electrolytes lost during exercise but contain less carbohydrates, are 2 types of postexercise drinks that have been formulated to address glycogen synthesis and carbohydrate replacement.
The current trial is a single-blind, randomized, crossover experimental study using endurance athletes as their own controls to compare the effect of 3 types of drinks: chocolate milk, FR, and CR with the equivalent carbohydrate content of chocolate milk, on performance as measured by time to exhaustion, average heart rate, rating of perceived exertion, and total work performed.
Study Highlights