Mammalian fuel utilization during sustained exercise
Mammalian fuel utilization during sustained exercise
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DOI：
10.1016/s0305-0491(98)00025-x
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发表时间：
1998-05-01
影响因子：
2.2
通讯作者：
Brooks, GA
中科院分区：
文献类型：
--
作者：
Brooks, GA
人类运动过程中底物利用的“交叉”和“乳酸穿梭”概念被扩展到描述其他哺乳动物物种的代谢反应。“交叉概念”是指脂质在维持需要一半或更少的有氧能力（(V) / dot O-2max）的努力中起主导作用；然而，更大的相对努力越来越依赖于血糖和肌糖原作为底物。因此，当运动强度从轻度增加到中度和高强度时，燃料选择从依赖脂质转向依赖碳水化合物。糖原和葡萄糖分解代谢率最好描述为运动强度的指数函数，但糖原的斜率比葡萄糖反应的斜率更大。相反，血浆游离脂肪酸通量被描述为顶点在点O-2max上约50% (V)的倒双曲线。在持续运动中，内分泌和细胞内因素在决定底物平衡中起关键作用。此外，有氧能力的基因型适应以及短期和长期慢性活动的表型适应会影响运动过程中底物利用的平衡。“乳酸穿梭”的概念是，在剧烈运动期间，以及其他加速糖酵解的条件下，无论氧合状态如何，肌肉中的糖酵解通量都涉及乳酸的形成。此外，根据乳酸穿梭概念，乳酸是分配碳水化合物氧化和糖异生势能的主要手段。在人类和其他哺乳动物中，乳酸（不是丙酮酸）的形成、分布和处置是持续运动中调节中间代谢的关键步骤。(C) 1998爱思唯尔科学有限公司版权所有。
The 'crossover' and 'lactate shuttle' concepts of substrate utilization in humans during exercise are extended to describe metabolic responses on other mammalian species. The 'crossover-concept' is that lipid plays a predominant role in sustaining efforts requiring half or less aerobic capacity ((V)over dot O-2max); however, greater relative efforts depend increasingly on blood glucose and muscle glycogen as substrates. Thus, as exercise intensity increases from mild to moderate and hard, fuel selection switches (crosses over) from lipid to carbohydrate dependence. Glycogen and glucose catabolic rates are best described as exponential functions of exercise intensity, but with a greater gain in slope of the glycogen than glucose response. in contrast, plasma free fatty acid flux is described as an inverted hyperbola with vertex at approximately 50% (V) over dot O-2max. Both endocrine and intra-cellular factors play critical roles in determining substrate balance during sustained exercise. Moreover, genotypic adaptation for aerobic capacity as well as phenotypic adaptations to short- and long-term chronic activity affect the balance of substrate utilization during exercise. The concept of a 'lactate shuttle' is that during hard exercise, as well as other conditions of accelerated glycolysis, glycolytic flux in muscle involves lactate formation regardless of the state of oxygenation. Further, according to the lactate shuttle concept, lactate represents a major means of distributing carbohydrate potential energy for oxidation and gluconeogenesis. In humans and other mammals, the formation, distribution and disposal of lactate (not pyruvate) represent key steps in the regulation of intermediary metabolism during sustained exercise. (C) 1998 Elsevier Science Inc. All rights reserved.