Magkos Faidon, Mohammed B Selma, Patterson Bruce W, Mittendorfer Bettina
Washington University School of Medicine, St Louis, MO 63110, USA; Department of Nutrition and Dietetics, Harokopio University, Athens 17671, Greece.
Metabolism. 2009 Sep;58(9):1248-55. doi: 10.1016/j.metabol.2009.03.023. Epub 2009 Jun 18.
Free fatty acid (FFA) availability increases several-fold during exercise and remains significantly elevated for at least 3 to 6 hours after exercise cessation. Little, however, is known regarding the duration of the postexercise rise in FFA flux. In the present study, we used stable isotope-labeled palmitate infusion to examine fatty acid metabolism in 27 healthy untrained men and women (age, 29 +/- 7 years; body mass index, 25 +/- 4 kg/m2) between 13 to 16 hours and 21 to 24 hours after a single bout of moderate-intensity endurance exercise (1-2 hours at 60% of peak oxygen consumption), performed in the evening, and after a time-matched resting trial. Postabsorptive FFA rate of appearance (Ra) and FFA concentration in plasma were significantly greater after exercise than rest throughout the recovery period (P < .015), but the exercise-induced increases declined from approximately 40% at 13 to 16 hours to approximately 10% at 21 to 24 hours postexercise (P = .001). The magnitude of the exercise-induced increase in plasma FFA concentration was proportional to the increase in FFA Ra. Correlation analysis demonstrated that exercise-induced changes in plasma FFA Ra at 13 to 16 hours are (1) negatively associated with resting plasma FFA Ra and (2) positively associated with the net energy expenditure of exercise and the exercise-induced changes in whole-body fat oxidation rate (all P values < .05). In multivariate stepwise linear regression analysis, baseline plasma FFA Ra (P < or = .008) and net energy expenditure of exercise (P < or = .005) independently predicted the exercise-induced change in plasma FFA Ra at 13 to 16 hours. We conclude that the exercise-induced increase in FFA mobilization is (1) long-lived, persisting for 12 to 24 hours after exercise, with a progressive decline with time; (2) greater in subjects with low than high resting plasma FFA availability; and (3) greater after exercise with high than low energy demand.
运动期间游离脂肪酸（FFA）的可利用性会增加数倍，并且在运动停止后至少3至6小时内仍会显著升高。然而，关于运动后FFA通量升高的持续时间，人们了解甚少。在本研究中，我们使用稳定同位素标记的棕榈酸输注，来检测27名健康的未经训练的男性和女性（年龄29±7岁；体重指数25±4kg/m²）在单次中等强度耐力运动（在峰值耗氧量的60%下进行1-2小时）后的13至16小时以及21至24小时，与时间匹配的静息试验后脂肪酸的代谢情况。在整个恢复期，运动后空腹状态下FFA的出现率（Ra）和血浆中FFA浓度均显著高于静息状态（P<.015），但运动诱导的升高从运动后13至16小时的约40%下降至21至24小时的约10%（P=.001）。运动诱导的血浆FFA浓度升高幅度与FFA Ra的升高成比例。相关分析表明，运动后13至16小时血浆FFA Ra的变化：（1）与静息血浆FFA Ra呈负相关；（2）与运动的净能量消耗以及运动诱导的全身脂肪氧化率变化呈正相关（所有P值<.05）。在多变量逐步线性回归分析中，基线血浆FFA Ra（P≤.008）和运动的净能量消耗（P≤.005）独立预测了运动后13至16小时血浆FFA Ra的变化。我们得出结论，运动诱导的FFA动员增加具有以下特点：（1）持续时间长，运动后持续12至24小时，并随时间逐渐下降；（2）静息血浆FFA可利用性低的受试者比高的受试者增加幅度更大；（3）能量需求高的运动后比能量需求低的运动后增加幅度更大。
