LAUSR

INTRODUCTION Protein ingestion during recovery from exercise has been reported to augment myofibrillar protein synthesis rates, without increasing muscle connective protein synthesis rates. It has been suggested that collagen protein may be effective in stimulating muscle connective protein synthesis. The present study assessed the capacity of both whey and collagen protein ingestion to stimulate post-exercise myofibrillar and muscle connective protein synthesis rates. METHODS In a randomized, double-blind, parallel design, 45 young male (n = 30) and female (n = 15) recreational athletes (age: 25 ± 4 y; BMI: 24.1 ± 2.0 kg/m2) were selected to receive primed continuous intravenous infusions with L-[ring-13C6]-phenylalanine and L-[3,5-2H2]-tyrosine. Following a single session of resistance type exercise, subjects were randomly allocated to one of three groups ingesting either 30 g whey protein (WHEY, n = 15), 30 g collagen protein (COLL, n = 15) or a non-caloric placebo (PLA, n = 15). Blood and muscle biopsy samples were collected over a subsequent 5-hour recovery period to assess both myofibrillar and muscle connective protein synthesis rates. RESULTS Protein ingestion increased circulating plasma amino acid concentrations (P < 0.05). The post-prandial rise in plasma leucine and essential amino acid concentrations was greater in WHEY compared with COLL, whereas plasma glycine and proline concentrations increased more in COLL compared with WHEY (P < 0.05). Myofibrillar protein synthesis rates averaged 0.041 ± 0.010, 0.036 ± 0.010 and 0.032 ± 0.007 %/h in WHEY, COLL and PLA, respectively, with only WHEY resulting in higher rates when compared with PLA (P < 0.05). Muscle connective protein synthesis rates averaged 0.072 ± 0.019, 0.068 ± 0.017, and 0.058 ± 0.018 %/h in WHEY, COLL and PLA, respectively, with no significant differences between groups (P = 0.09). CONCLUSIONS Ingestion of whey protein during recovery from exercise increases myofibrillar protein synthesis rates. Neither collagen nor whey protein ingestion further increased muscle connective protein synthesis rates during the early stages of post-exercise recovery in both male and female recreational athletes.