EFFECT OF GLUCOSE SUPPLEMENT TIMING ON PROTEIN-METABOLISM AFTER RESISTANCE TRAINING

We determined the effect of the timing of glucose supplementation an f ractional 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 exercis e (8 sets/similar to 10 repetitions/similar to 85% of 1 single maximal repetition). They received a carbohydrate (CHO) supplement (1 g/kg) o r placebo (PI) immediately (t = 0 h) and 1 h (t = +1 h) postexercise. FSR was determined for exercised (Ex) and control (Con) limbs by incre mental L-[1-C-13]leucine enrichment into the vastus lateralis over sim ilar to 10 h postexercise. Insulin was greater (P < 0.01) at 0.5, 0.75 , 1.25, 1.5, 1.75, and 2 h, and glucose was greater (P < 0.05) at 0.5 and 0.76 h for CHO compared with P1 condition. FSR was 36.1% greater i n the CHO/Ex leg than in the CHO/Con leg (P = not significant) and 6.3 % greater in the Pl/Ex leg than in the Pl/Con leg (P = not significant ). 3-Methylhistidine excretion was lower in the CHO (110.43 +/- 3.62 m u mol/g creatinine) than PI condition (120.14 +/- 5.82, P < 0.05) as w as urinary urea nitrogen (8.60 +/- 0.06 vs. 12.28 +/- 1.84 g/g creatin ine, P < 0.05). This suggests that CHO supplementation (1 g/kg) immedi ately and 1 h after resistance exercise can decrease myofibrillar prot ein breakdown and urinary urea excretion, resulting in a more positive body protein balance.