Timing and distribution of protein ingestion during prolonged recovery from resistance exercise alters myofibrillar protein synthesis


J. A. Hawley: School of Medical Sciences, RMIT University, Bundoora, Victoria 3083, Australia. Email: john.hawley@rmit.edu.au

Key points

  • • A single bolus of ∼20 g of protein after a bout of resistance exercise provides a maximal anabolic stimulus during the early post-exercise recovery period (∼5 h), but the effect of various protein feeding strategies on skeletal muscle protein synthesis during an extended recovery period (12 h) is unknown.
  • • We compared three different patterns of ingestion of 80 g of protein during 12 h recovery after resistance exercise and the associated anabolic response in human skeletal muscle. Protein was ingested in 10, 20 or 40 g feedings using a pulsed, intermediate or bolus ingestion regimen, respectively.
  • • Our results indicate that repeated ingestion of 20 g of protein was superior for stimulating muscle protein synthesis during the 12 h experimental period.
  • • The three dietary treatments induced differential phosphorylation of signalling proteins and changes in mRNA abundance.
  • • This study shows that the distribution of protein intake is an important variable to promote attainment and maintenance of peak muscle mass.

Abstract  Quantity and timing of protein ingestion are major factors regulating myofibrillar protein synthesis (MPS). However, the effect of specific ingestion patterns on MPS throughout a 12 h period is unknown. We determined how different distributions of protein feeding during 12 h recovery after resistance exercise affects anabolic responses in skeletal muscle. Twenty-four healthy trained males were assigned to three groups (n= 8/group) and undertook a bout of resistance exercise followed by ingestion of 80 g of whey protein throughout 12 h recovery in one of the following protocols: 8 × 10 g every 1.5 h (PULSE); 4 × 20 g every 3 h (intermediate: INT); or 2 × 40 g every 6 h (BOLUS). Muscle biopsies were obtained at rest and after 1, 4, 6, 7 and 12 h post exercise. Resting and post-exercise MPS (l-[ring-13C6] phenylalanine), and muscle mRNA abundance and cell signalling were assessed. All ingestion protocols increased MPS above rest throughout 1–12 h recovery (88–148%, P < 0.02), but INT elicited greater MPS than PULSE and BOLUS (31–48%, P < 0.02). In general signalling showed a BOLUS>INT>PULSE hierarchy in magnitude of phosphorylation. MuRF-1 and SLC38A2 mRNA were differentially expressed with BOLUS. In conclusion, 20 g of whey protein consumed every 3 h was superior to either PULSE or BOLUS feeding patterns for stimulating MPS throughout the day. This study provides novel information on the effect of modulating the distribution of protein intake on anabolic responses in skeletal muscle and has the potential to maximize outcomes of resistance training for attaining peak muscle mass.