Macronutrient intake and whole body protein metabolism following resistance exercise

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ROY, B. D., J. R. FOWLES, R. HILL, and M A. TARNOPOLSKY. Macronutrient intake and whole body protein metabolism following resistance exercise. Med. Sci. Sports Exerc., Vol. 32, No. 8, pp. 1412–1418, 2000. The provision of carbohydrate (CHO) supplements following resistance exercise attenuated muscle protein (PRO) degradation (Roy et al. J. Appl. Physiol. 82:1882–1888, 1997). The addition of PRO may have a synergistic effect upon whole body protein balance by increasing synthesis (Biolo et al. Am. J. Physiol. 273:E122–E129, 1997).PurposeTo determine if the macronutrient composition of a postexercise beverage would alter muscle anabolism and/or catabolism following resistance exercise.MethodsWe provided isoenergetic CHO (1 g·kg−1) and CHO/PRO/FAT supplements and placebo (PL) immediately (t = 0 h) and 1 h (t = +1 h) following resistance exercise (9 exercises/3 sets/80% 1 RM) to 10 young, healthy, resistance-trained males. Whole body leucine turnover was determined from L-[1-13C]leucine kinetics at ∼4 h postexercise.ResultsNo differences were observed for urinary 3-methylhistidine or urea nitrogen excretion between the trials. Leucine flux was significantly elevated at ∼4 h postexercise for both CHO/PRO/FAT (177.59 ± 12.68 μmol·kg−1·h−1) and CHO (156.18 ± 7.77 μmol·kg−1·h−1) versus PL (126.32 ± 10.51 μmol·kg−1·h−1) (P < 0.01). Whole body leucine oxidation was elevated at ∼4 h for CHO/PRO/FAT (29.50 ± 3.34 μmol·kg−1·h−1) versus CHO (16.32 ± 2.33 μmol·kg−1·h−1) (P < 0.01) and PL (21.29 ± 2.54 μmol·kg−1·h−1) (P < 0.05). Nonoxidative leucine disposal (NOLD) was significantly elevated at ∼4 h for both CHO/PRO/FAT (148.09 ± 10.37 μmol·kg−1·h−1) and CHO (139.86 ± 7.02 μmol·kg−1·h−1) versus PL (105.03 ± 8.97 μmol·kg−1·h−1) (P < 0.01).ConclusionsThese results suggest that consumption of either CHO or CHO/PRO/FAT immediately and 1 h following a resistance training bout increased NOLD as compared with a placebo.

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