Postexercise ‘window of potential’ for the stimulation of muscle protein synthesis
Resistance exercise and protein intake work synergistically to stimulate muscle protein synthesis. An improved understanding of the optimal nutritional strategies to maximize postexercise muscle protein synthesis has been gained in recent years. Dietary factors such as protein quanity, amino acid composition, and speed of protein digestion can be manipulated to improve the immediate postexercise recovery gain in muscle protein. Recently, interest has emerged in nutritional timing strategies to improve muscle protein synthesis rates during the prolonged postexercise recovery. Specifically, protein ingestion prior to sleep and the days after exercise appear to be crucial to further augment skeletal muscle reconditioning. A brief review of the current knowledge in this field of research will be provided.
Resistance exercise, when practiced regularly, is a potent stimulus to increase skeletal muscle mass. A prolonged positive net protein balance is necessary to promote gains in lean mass and consequent strength gains. In healthy individuals, a positive net muscle protein balance is generally driven by changes in rates of muscle protein synthesis as opposed to changes in muscle protein breakdown rates. For instance, a single bout of resistance exercise can increase muscle protein synthesis rates by ~100-150% when compared to the non-exercise state, whereas a much smaller change (15-30%) occurs in muscle protein breakdown (1). Although resistance exercise is fundamentally anabolic, protein ingestion during exercise recovery is required to promote a positive net muscle protein balance and therefore the skeletal muscle adaptive response. It has been established that nutritional manipulations immediately after exercise can further support the gain in net muscle protein. In particular, this work has established that the type (2), timing (3), and quantity (4) of protein ingested can modulate postexercise muscle protein synthesis rates.