Assessing the regulation of skeletal muscle plasticity in response to protein ingestion and resistance exercise

PURPOSE OF REVIEW: The main purpose of this review is to discuss novel methodological advances in the assessment of muscle protein synthesis (MPS) in response to protein feeding and resistance exercise. RECENT FINDINGS: In the past 20 years, there has been a shift from application of the nitrogen balance methods toward the infusion of stable isotopic tracers to assess rates of MPS in response to a range of perturbations. Although this approach has enabled MPS to be assessed with a greater temporal resolution and precision, the method limits the capture of MPS to relatively short-duration infusions of approximately 3-12 h. Recent refinement of analytical methods to assess long-term MPS responses have now provided a platform for studying the impact of exercise and nutrition on muscle anabolism with an extended temporal resolution from hours to days or even weeks. Finally, novel insights into cellular signaling processes may help delineate the molecular mechanisms that govern skeletal muscle plasticity in response to exercise and feeding. SUMMARY: Future work should focus on the impact of novel exercise and nutritional interventions on MPS in an extended postexercise adaptive period, that is, days. The findings of such investigations will help test the long-term efficacy of interventions to enhance skeletal muscle protein reconditioning and hypertrophy.