Institute of Membrane and Systems Biology, University of Leeds, Leeds, United Kingdom.
Compr Physiol. 2011 Jan;1(1):203-44. doi: 10.1002/cphy.c090010.
The activities of daily living typically occur at metabolic rates below the maximum rate of aerobic energy production. Such activity is characteristic of the nonsteady state, where energy demands, and consequential physiological responses, are in constant flux. The dynamics of the integrated physiological processes during these activities determine the degree to which exercise can be supported through rates of O₂ utilization and CO₂ clearance appropriate for their demands and, as such, provide a physiological framework for the notion of exercise intensity. The rate at which O₂ exchange responds to meet the changing energy demands of exercise--its kinetics--is dependent on the ability of the pulmonary, circulatory, and muscle bioenergetic systems to respond appropriately. Slow response kinetics in pulmonary O₂ uptake predispose toward a greater necessity for substrate-level energy supply, processes that are limited in their capacity, challenge system homeostasis and hence contribute to exercise intolerance. This review provides a physiological systems perspective of pulmonary gas exchange kinetics: from an integrative view on the control of muscle oxygen consumption kinetics to the dissociation of cellular respiration from its pulmonary expression by the circulatory dynamics and the gas capacitance of the lungs, blood, and tissues. The intensity dependence of gas exchange kinetics is discussed in relation to constant, intermittent, and ramped work rate changes. The influence of heterogeneity in the kinetic matching of O₂ delivery to utilization is presented in reference to exercise tolerance in endurance-trained athletes, the elderly, and patients with chronic heart or lung disease.
日常生活活动通常发生在代谢率低于有氧能量产生的最大速率的情况下。这种活动是稳态的特征，其中能量需求和随之而来的生理反应是不断变化的。在这些活动期间，综合生理过程的动态决定了运动可以通过适当的 O₂利用和 CO₂清除率来支持的程度，因此为运动强度的概念提供了生理框架。O₂交换率响应以满足运动不断变化的能量需求的速度——其动力学——取决于肺、循环和肌肉生物能量系统适当响应的能力。肺摄取 O₂的缓慢反应动力学倾向于更大的底物水平能量供应的必要性，这些过程的能力有限，挑战系统的动态平衡，从而导致运动不耐受。本综述提供了肺气体交换动力学的生理系统观点：从肌肉氧消耗动力学控制的综合观点到循环动力学和肺、血液和组织的气体电容从其肺表达中分离出细胞呼吸。讨论了气体交换动力学的强度依赖性与恒速、间歇和斜坡工作速率变化的关系。在提到耐力训练运动员、老年人和患有慢性心脏或肺部疾病的患者的运动耐力时，还介绍了 O₂输送与利用的动力学匹配的异质性的影响。
