The anabolic potential of dietary protein intake on skeletal muscle is prolonged by prior light-load exercise

Summary Background & aims Hyperaminoacidemia stimulates myofibrillar fractional synthesis rate (myoFSR) transiently in resting skeletal muscle. We investigated whether light-load resistance exercise can extent this responsiveness. Methods Ten healthy males exercised one leg with a light-load resistance-like exercise at 16% of 1 repetition maximum and received oral protein boluses every hour for a 10-h period. Their myoFSR was determined by [1- 13 C]-leucine incorporation. Muscle biopsies were obtained from the resting (REST) and exercised (EXC) muscles every 2.5-h in the protein-fed period. Results Protein feeding significantly elevated plasma leucine and essential amino acids by an average of 39 ± 9% (mean ± SEM) and 20 ± 4%, respectively, compared to the basal concentrations: 197 ± 12 μmol L −1 and 854 ± 35 μmol L −1 , respectively. The myoFSR was similar in EXC and REST muscles in the first 8 h (all time intervals p  > 0.05). After 8 h the myoFSR dropped in the REST muscle to 0.041 ± 0.005%·h −1 , which was 65 ± 5% of the rate in EXC leg at the same time point (0.062 ± 0.004%·h −1 ) and 80 ± 14% of the level in REST leg from 0.5 to 8 h (0.056 ± 0.005%·h −1 ) (interaction p Conclusions Compared to rest, light-load exercise prolonged the stimulatory effect of dietary protein on muscle biosynthesis providing perspectives for a muscle restorative effect in clinical settings where strenuous activity is intolerable.