The amino acids in protein serve as building blocks for muscle proteins and as chemical signalers for turning on protein synthesis after exercise. An ongoing controversy in sports nutrition is the timing of protein intake before or after exercise. In older people, consuming protein before exercise might interfere with protein absorption from the gastrointestinal tract.
A Dutch study of older and younger men found that consuming protein after exercise boosted protein synthesis, and age did not influence the results. Consuming proteins after exercise, either as a meal or as part of a supplement, turns on protein synthesis and maximizes the benefit of the exercise program. (American Journal of Clinical Nutrition, published online)