Martin W H
Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA.
Med Sci Sports Exerc. 1997 May;29(5):635-9. doi: 10.1097/00005768-199705000-00008.
Endurance exercise training increases fat oxidation during large muscle mass exercise. Although the source of this fat has been thought to be plasma free fatty acids (FFA) released from adipose tissue, the training-induced decrease in lipolytic hormonal responses to exercise is not consistent with this concept. The purpose of this communication is to review findings, from our laboratory indicating that, in young healthy subjects, endurance exercise training reduces plasma FFA turnover and oxidation during moderate intensity prolonged 2-leg cycling while simultaneously enhancing depletion of triglycerides from the active musculature. Evidence is presented that metabolism of intramuscular triglycerides can explain the increase in total fat oxidation observed in the trained state during large muscle mass exercise. However, these results may not be applicable to exercise involving small muscle groups, a distinction that is likely to be important in explaining the apparent conflict between our findings and those from other laboratories where experimental conditions were different. In summary, for large muscle mass exercise up to 2 h in duration, plasma FFA are a less important fuel source in the trained state, and intramuscular triglycerides supply the major portion of the increase in oxidized fatty acids.
耐力运动训练可增加大肌群运动期间的脂肪氧化。尽管一直认为这种脂肪的来源是从脂肪组织释放的血浆游离脂肪酸（FFA），但训练引起的对运动的脂解激素反应降低与这一概念并不一致。本通讯的目的是回顾我们实验室的研究结果，这些结果表明，在年轻健康受试者中，耐力运动训练会降低中等强度长时间双腿骑行期间的血浆FFA周转率和氧化，同时增强活跃肌肉组织中甘油三酯的消耗。有证据表明，肌内甘油三酯的代谢可以解释在大肌群运动的训练状态下观察到的总脂肪氧化增加。然而，这些结果可能不适用于涉及小肌群的运动，这一区别在解释我们的研究结果与其他实验条件不同的实验室的结果之间明显的冲突时可能很重要。总之，对于持续时间长达2小时的大肌群运动，在训练状态下血浆FFA是不太重要的燃料来源，肌内甘油三酯提供了氧化脂肪酸增加的主要部分。
