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This investigation evaluated the physiological impact of different dietary protein intakes on skeletal muscle protein synthesis postexercise in endurance runners. Five endurance-trained, male runners participated in a randomized, crossover design diet intervention, where they consumed either a low (0.8 g/kg; LP)-, moderate (1.8 g/kg; MP)-, or high (3.6 g/kg; HP)-protein diet for 4 wk. Diets were designed to be eucaloric with carbohydrate, fat, and protein approximating 60, 30, and 10%; 55, 30, and 15%; and 40, 30, and 30% for LP, MP, and HP, respectively. Substrate oxidation was assessed via indirect calorimetry at 3 wk of the dietary interventions. Mixed-muscle protein fractional synthetic rate (FSR) was measured after an endurance run (75 rain at 70% VO2 peak) using a primed, continuous infusion of [²H5]phenylalanine. Protein oxidation increased with increasing protein intake, with each trial being significantly different from the other (P « 0.01). FSR after exercise was significantly greater for LP (0.083%/h) and MP (0.078%/h) than for HP (0.052%/h; P « 0.05). There was no difference in FSR between LP and MP. This is the first investigation to establish that habitual dietary protein intake in humans modulates skeletal muscle protein synthesis after an endurance exercise bout. Future studies directed at mechanisms by which level of protein intake influences skeletal muscle turnover are needed. [ABSTRACT FROM AUTHOR]

Presents a study that examined the time course changes in serum insulin concentrations in food-deprived rats after an oral bolus of leucine. Examination of the contribution of changes in serum concentrations of insulin to the increase in protein synthesis; Circulating insulin concentrations in food-deprived rats infused with somatostatin and leucine; Chemical essential for the enhanced rates of protein synthesis observed in skeletal muscle after food intake.

Provides information on a study which evaluated an approach for determining skeletal muscle-specific glucose flux using radioactive stereoisomers and the microdialysis technique. Methods; Results; Discussion.

Investigates the effect of dynamic exercise on mean blood velocity and muscle interstitial metabolite responses of humans. Increase in interstitial adenosine from rest to exercise; Role of potassium and adenosine in the regulation of skeletal muscle blood flow during.