Adding protein to a carbohydrate drink increases skeletal muscle protein synthesis during recovery from prolonged aerobic exercise

Protein (PRO) ingestion with carbohydrate (CHO) during recovery from prolonged exercise may promote muscle glycogen synthesis; however, an additional benefit may be an increase in muscle protein synthesis. This study used stable isotope tracer methodology to examine the effect of CHO or CHO+PRO ingestion on mixed skeletal muscle protein fractional synthetic rates (FSR) following prolonged exercise. Six men (22±1 yr) performed 2 h of cycle exercise to reduce body CHO stores. Following exercise, subjects ingested either a CHO+PRO drink (1.2g CHO + 0.4g PRO/kg/h), an iso‐CHO drink (L‐CHO: 1.2g CHO/kg/h) or an iso‐energetic CHO drink (H‐CHO: 1.6g CHO/kg/h) every 15 min for 3 h. Subjects completed all trials in random order, separated by 1 wk. Prior to each trial, subjects received a primed constant infusion of L‐[ring‐ 2 H 5 ]‐phenylalanine (Phe) and muscle FSR was determined from biopsies (v lateralis) obtained at 0 and 4 h of recovery. Analysis of variance revealed that muscle FSR was higher in the CHO+PRO trial (0.088±0.008 %/h) compared to both CHO trials (L‐CHO: 0.066±0.006, H‐CHO: 0.060±0.007; p<0.05). We conclude that adding PRO to a CHO drink increases muscle protein synthesis during recovery from prolonged exercise compared to CHO alone. The higher FSR during recovery may promote the muscle adaptive response to training by facilitating synthesis of new proteins stimulated by exercise. Supported by NSERC, Canada.