To evaluate the effect that protein and glucose supplement intake during a long-term, high-intensity training program has on muscle soreness and health.

387 new male and female conscripts in the US Marine Corps were given either a protein and glucose supplement (10g protein, 8g glucose, 3g fat), glucose placebo (0g protein, 8g glucose, 3g fat), or calorie-free placebo (0g protein, 0g glucose, 0g fat), and a parallel-group comparison study performed. During a 54-week boot camp for new conscripts, the test was performed during a 3-day conditioning hike (3, 5, and 10-mile walks) and a 24-day running program (1-3 miles per day), which also included crunches, push-ups, and chin-ups. The training period was additionally supplemented with a 6-day martial arts training program, 4 days of swimming conditioning, and a 3+ mile/day walking regimen. Subjects consumed the above supplements and placebos immediately after each exercise regimen. A subjective score of muscle soreness was performed immediately after exercise and twenty-four hours thereafter. Dedicated physicians evaluated the health and treatment of subjects during the camp period.

The change in muscle soreness scores from the start of the regimen to the 34th day and 54th day was lower in the group consuming protein and glucose supplements than in the other two groups. Furthermore, the total number of subjects visiting the clinic for bacterial and viral infections, muscle and joint injury, heat exhaustion, and other symptoms was 108 persons in the group consuming a glucose and protein supplement, a significantly lower number than in the other two groups (glucose placebo group: 153; calorie-free group: 169).

Not only does consumption of a protein and glucose supplement immediately after exercise promote growth in skeletal muscle mass, but it promotes better health when engaging in a continuous regimen of high-intensity training and can help reduce muscle soreness. The results suggest that an intake of protein can help prevent health issues in people engaging in exercises that involve severe physical stress.