Physical Activity Performed in the Evening Increases the Overnight Muscle Protein Synthetic Response to Presleep Protein Ingestion in Older Men

Background: The age-related decline in skeletal muscle mass is partly attributed to anabolic resistance to food intake. Dietary protein ingestion before sleep could be used as a nutritional strategy to compensate for anabolic resistance. Objective: The present study assessed whether physical activity performed in the evening can augment the overnight muscle protein synthetic response to presleep protein ingestion in older men. Methods: In a parallel group design, 23 healthy older men (mean SEM age: 71 1 y) were randomly assigned to ingest 40 g protein intrinsically labeled with L[1-C-13]-phenylalanine and L-[1-C-13]-leucine before going to sleep with (PRO+EX) or without (PRO) performing physical activity earlier in the evening. Overnight protein digestion and absorption kinetics and myofibrillar protein synthesis rates were assessed by combining primed, continuous infusions of L-[ring-H-2(5)]-phenylalanine, L-[1-C-13]-leucine, and L-[ring-H-2(2)]-tyrosine with the ingestion of intrinsically labeled casein protein. Muscle and blood samples were collected throughout overnight sleep. Results: Protein ingested before sleep was normally digested and absorbed, with 54% +/- 2% of the protein-derived amino acids appearing in the circulation throughout overnight sleep. Overnight myofibrillar protein synthesis rates were 31 % (0.058% +/- 0.002%/h compared with 0.044% +/- 0.003%/h; P <0.01; based on L-[ring-H-2(5)]-phenylalanine) and 27% (0.074% +/- 0.004%/h compared with 0.058% +/- 0.003%/h; P <0.01; based on L-[1-C-13]-leucine) higher in the PRO+EX than in the PRO treatment. More dietary protein-derived amino acids were incorporated into de novo myofibrillar protein during overnight sleep in PRO+EX than in PRO treatment (0.042 +/- 0.002 compared with 0.033 +/- 0.002 mole percent excess; P <0.05). Conclusions: Physical activity performed in the evening augments the overnight muscle protein synthetic response to presleep protein ingestion and allows more of the ingested protein-derived amino acids to be used for de novo muscle protein synthesis during overnight sleep in older men. This trial was registered at Nederlands Trial Register as NTR3885.