In contrast to the impact of nutritional intervention on post-exercise muscle protein synthesis, little is known about the potential to modulate protein synthesis during exercise. This study investigates the impact of protein co-ingestion with carbohydrate on muscle protein synthesis during resistance type exercise. Ten healthy males were studied in the evening after consuming a standardized diet throughout the day. Subjects participated in 2 experiments, in which they ingested either carbohydrate or carbohydrate with protein during a 2h resistance exercise session. Subjects received a bolus of test drink prior to and every 15 min during exercise, providing 0.15 g.kg(-1).h(-1) carbohydrate with (CHO+PRO) or without (CHO) 0.15 g.kg(-1).h(-1) protein hydrolysate. Continuous intravenous infusions with L-[ring-(13)C6]phenylalanine and L-[ring-(2)H2] tyrosine were applied, and blood and muscle biopsies were collected to assess whole-body and muscle protein synthesis rates during exercise. Protein co-ingestion lowered whole-body protein breakdown rates by 8.4+/-3.6% (P=0.066), compared to the ingestion of carbohydrate only, and augmented protein oxidation and synthesis rates by 77+/-17 and 33+/-3%, respectively (P<0.01). As a consequence, whole-body net protein balance was negative in CHO, whereas a positive net balance was achieved following the CHO+PRO treatment (-4.4+/-0.3 vs 16.3+/-0.4 micromol phe.kg(-1).h(-1), respectively; P<0.01). In accordance, mixed muscle protein fractional synthetic rate (FSR) was 49+/-22% higher following protein co-ingestion (0.088+/-0.012 and 0.060+/-0.004 %.h(-1) in CHO+PRO vs CHO treatment, respectively; P<0.05). We conclude that, even in a fed state, protein co-ingestion stimulates whole-body and muscle protein synthesis rates during resistance type exercise. Key words: muscle, protein synthesis, exercise, nutrition.
|Journal||American Journal of Physiology : Endocrinology and Metabolism|
|Publication status||Published - 1 Jan 2008|