Macronutrient intake and whole body protein metabolism following resistance exercise
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UNLABELLED: 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). PURPOSE: To determine if the macronutrient composition of a postexercise beverage would alter muscle anabolism and/or catabolism following resistance exercise. METHODS: We provided isoenergetic CHO (1 g x 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 approximately 4 h postexercise. RESULTS: No differences were observed for urinary 3-methylhistidine or urea nitrogen excretion between the trials. Leucine flux was significantly elevated at approximately 4 h postexercise for both CHO/PRO/FAT (177.59+/-12.68 micromol x kg(-1) x h(-1)) and CHO (156.18+/-7.77 micromol x kg(-1) x h(-1)) versus PL (126.32+/-10.51 micromol x kg(-1) x h(-1)) (P < 0.01). Whole body leucine oxidation was elevated at approximately 4 h for CHO/PRO/FAT (29.50+/-3.34 micromol x kg(-1) h(-1)) versus CHO (16.32+/-2.33 micromol x kg(-1) x h(-1)) (P < 0.01) and PL (21.29+/-2.54 micromol x kg(-1) x h(-1)) (P < 0.05). Nonoxidative leucine disposal (NOLD) was significantly elevated at approximately 4 h for both CHO/PRO/FAT (148.09+/-10.37 micromol x kg(-1) x h(-1)) and CHO (139.86+/-7.02 micromol x kg(-1) x h(-1)) versus PL (105.03+/-8.97 micromol x kg(-1) x h(-1)) (P < 0.01). CONCLUSIONS: These 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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