增補脫脂牛奶對中強度耐力運動表現及生理反應之影響

Purpose: To investigate the effect of skim milk supplement on the moderate endurance performance and physiological responses. Methods: Nine college male athletes voluntarily participated in this randomized and crossover designed study, and completed 2 trials separated by at least 7 days: skim milk (SM) and water (W) treatments. Before treatment, the incremental cycling exercise test was performed on a cycle ergometer to assess maximal oxygen uptake (VO2max) and power output at VO2max (Pmax). In each trial, participants were asked to perform a glycogen-depleting exercise followed by 4-h of recovery, and a sub maximal cycling exercise at 70%Pmax to exhaustion. Immediately following first exercise bout and 2-h of recovery, participants consumed either SM or W. Blood lactate (La), heart rate (HR), oxygen uptake (VO,), respiratory exchange ratio (RER), time to exhaustion (TTE), rating of perceived exertion (RPE) and free fatty acid (FFA) were continuously measured throughout the trial. Results: No significant differences were found on the TTE, VO2, HR and RPE during the 70%Pmax submaximal cycling exercise between SM and W (p ＞ .05). However, the FFA (SM vs. W, 0.13 ± 0.05 vs. 0.66 ± 0.26 mmol．L^(-1),p ＜ .05) and La (SM vs. W, 1.1 ± 0.2 vs. 1.4 ± 0.5 mmol．L^(-1), p ＜ .05) in W after supplement were significantly higher than those in SM. The RER in SM were significantly lower than those in W at 50%TTE (SM vs. W, 0.88 ± 0.06 vs. 0.93 ± 0.05, p ＜ .05) and 100%TIE (SM vs. W, 0.87 ± 0.07 vs. 0.93 ± 0.05, p ＜ .05) during the 70%Pmax submaximal cycling exercise. Moreover, the fat oxidation rates in SM were significantly higher than those in W at 50% ~ 100% TTE (SM vs. W, 0.56 ± 0.04 vs. 0.28 ± 0.02 g．min^(-1),p ＜ .05), during the 70% Pmax submaximal cycling exercise. Conclusion: These results suggest that skim milk is an effective recovery aid after exhaustive exercise, and it can increase the fat oxidation rate during the moderate exercise.