Abstract des Autors

We determined the effect of the timing of glucose supplementation on fractional muscle protein synthetic rate (FSR), urinary urea excretion, and whole body and myofibrillar protein degradation after resistance exercise. Eight healthy men performed unilateral knee extensor exercise (8 sets/ca 10 repetitions/ca. 85% of 1 single maximal repetition). They received a carbohydrate (CHO) supplement (1 g/kg) or placebo (PI) immediately (t=0 h) and 1 h (t=+1 h) postexercise. FSR was determined for exercised (Ex) and control (Con) limbs by incremental L-[1-13C]leucine enrichment into the vastus lateralis over ca. 10 h postexercise. Insulin was greater at 0.5, 0.75, 1.25, 1.5, 1.75, and 2 h, and glucose was greater at 0.5 and 0.75 h for CHO compared with Pl condition. FSR was 36.1% greater in the CHO/Ex leg than in the CHO/Con leg and 6.3% greater in the Pl/Ex leg than in the Pl/Con leg. 3-Methylhistidine excretion was lower in the CHO (110.43+/-3.62 micro-mol/g creatinine) than Pl condition (120.14+/-5.82, P<0.05) as was urinary urea nitrogen (8.60+/-0.66 vs. 12.28+/-1.84 g/g creatinine, P<0.05). This suggests that CHO supplementation (1 g/kg) immediately and 1 h after resistance exercises can decrease myofibrillar protein breakdown and urinary urea excretion, resulting in a more positive body protein balance. Verf.-Referat