Neuromuscular electrical stimulation prior to pre-sleep protein feeding stimulates the use of protein-derived amino acids for overnight muscle protein synthesis.

Abstract

BACKGROUND: Short periods of muscle disuse result in substantial skeletal muscle atrophy. Recently, we showed that both neuromuscular electrical stimulation (NMES) as well as pre-sleep dietary protein ingestion represent effective strategies to stimulate muscle protein synthesis rates. In this study we test our hypothesis that NMES can augment the use of pre-sleep protein-derived amino acids for overnight muscle protein synthesis in older males. METHODS: Twenty healthy, older (69±1 y) males were subjected to 24 h of bed rest, starting at 8:00 AM. In the evening, volunteers were subjected to 70 min one-legged NMES, while the other leg served as non-stimulated control (CON). Immediately following NMES, 40 g intrinsically L-[1-(13)C]-phenylalanine labeled protein was ingested prior to sleep. Blood samples were taken throughout the night, and muscle biopsies were obtained from both legs in the evening and the following morning (8 h after protein ingestion) to assess dietary protein-derived L-[1-(13)C]-phenylalanine enrichments in myofibrillar protein. RESULTS: Plasma phenylalanine concentrations and plasma L-[1-(13)C]-phenylalanine enrichments increased significantly following protein ingestion and remained elevated for up to 6 hours after protein ingestion (P<0.05). During overnight sleep, myofibrillar protein-bound L-[1-(13)C]-phenylalanine enrichments increased to a greater extent in the stimulated compared with the control leg (0.0344±0.0019 vs 0.0297±0.0016 MPE, respectively; P<0.01), representing 18±6% greater incorporation of pre-sleep protein-derived amino acids in the NMES compared with CON leg. CONCLUSIONS: Application of NMES prior to pre-sleep protein feeding stimulates the use of dietary protein-derived amino acids for overnight muscle protein synthesis in older males.