Dietary protein and/or carbohydrate consumption augments postexercise recovery by facilitating the rebuilding of damaged contractile tissues and restoring energy reserves. What is unknown is how altering postexercise nutrient timing affects the shift towards fat utilization after a resistance training bout, in addition to changes in net protein retention. PURPOSE: To examine the effects of immediate versus delayed postexercise nutrient intake on postexercise fat and carbohydrate oxidation, nitrogen balance, and cortisol during 3 hours of recovery. METHODS: Resistance trained (≥ 1 y) men (n = 10, 22 ± 2 y, 83 ± 10 kg) performed a resistance exercise bout (3 sets of 6 exercises that stimulate major muscle groups, 2–3 minutes of rest). Participants then consumed one of the three following postexercise nutrition interventions: immediate consumption of a whey protein concentrate (0.35 g/kg) and dextrose carbohydrate (1.0 g/kg) beverage (IMM), delayed consumption (2 h) of a whey and dextrose beverage (+2H), or placebo (flavoring with water; PLA). Participants recovered for three hours while expired carbon dioxide and oxygen were collected. Substrate oxidation (carbohydrate and fat) and energy expenditure were determined, in addition to body protein breakdown (via the analyses of the hormone cortisol and urinary protein excretion). RESULTS: Nitrogen balance was significantly lower in PLA (-0.02 ± .01g) compared to +2H (5.21 ± 0.63 g, p ≤ 0.001, ES = 11.61) and IMM (5.21 ± 0.64 g) (p ≤ 0.001, ES = 11.59) during the three-hour recovery. There were no significant differences in nitrogen balance in IMM compared with +2H (p = 1.0). Carbohydrate oxidation was significantly higher in IMM, compared with +2H, 60 minutes postexercise (0.21 ± 0.13 g/min vs. 0.11 ± 0.12 g/min, respectively) (p = 0.014). Fat oxidation was higher in +2H compared with IMM minute 90 (p > 0.05, ES = 0.60), minute 120 (p > 0.05, ES = 0.40), and minute 150 (p > 0.05, ES = 0.50). There were no significant differences in salivary cortisol among groups (all p = 1.0). CONCLUSION: Delayed nutrient intake promotes higher fat utilization, whereas IMM nutrient intake promotes greater carbohydrate oxidation earlier in the recovery period. Additionally, both interventions result in similar net protein retention. Thus, postponing postexercise nutrient intake may have implications in favorable body composition improvements.
|Advisor:||Lunn, William, Talpey, Scott|
|School:||Southern Connecticut State University|
|School Location:||United States -- Connecticut|
|Source:||MAI 81/2(E), Masters Abstracts International|
|Subjects:||Kinesiology, Gender studies, Nutrition|
|Keywords:||Energy expenditure, Nutrient timing, Postexercise nutrient timing, Protein retention, Resistance-trained men, Susbtrate oxidation|
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