Determinants and detection of anaerobic threshold and consequences of exercise above it.
Determinants and detection of anaerobic threshold and consequences of exercise above it.
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作者：
K. Wasserman
在运动过程中，耗氧量（VO 2）水平被称为无氧阈值，高于该耗氧量水平，有氧能量产生由无氧机制补充，导致乳酸持续增加和代谢性酸中毒。发生无氧阈值的VO 2受影响向组织输送氧气的因素的影响，当氧气流量增加时增加，当氧气流量减少时减少。无氧阈是一个重要的功能分界点，因为无氧阈以上和无氧阈以下对运动的生理反应是不同的。在无氧阈值以上，除了代谢性酸中毒的发展之外，运动耐力降低，VO 2动力学减慢，使得稳态延迟，每分钟通气量与代谢需求不成比例地增加，并发展为进行性呼吸急促。无氧阈值可以直接从乳酸浓度测量，具有来自乳酸和VO 2的对数-对数转换的良好阈值检测。该阈值定义了乳酸/丙酮酸比率增加时的VO 2。由于碳酸氢盐随乳酸盐的变化而变化，因此其测量也可用于估计乳酸盐阈值。但最方便的是，由碳酸氢盐缓冲乳酸的物理化学事件引起的气体交换的变化可用于检测运动期间的无氧阈值。
During exercise, the level of oxygen consumption (VO2) above which aerobic energy production is supplemented by anaerobic mechanisms causing a sustained increase in lactate and metabolic acidosis is termed the anaerobic threshold. The VO2 at which the anaerobic threshold occurs is influenced by the factors that affect oxygen delivery to the tissues, being increased when oxygen flow is enhanced and decreased when oxygen flow is diminished. The anaerobic threshold is an important functional demarcation since the physiologic responses to exercise are different above the anaerobic threshold as compared with below the anaerobic threshold. Above the anaerobic threshold, in addition to the development of metabolic acidosis, exercise endurance is reduced, VO2 kinetics are slowed so that a steady state is delayed, and minute ventilation increases disproportionately to the metabolic requirement and a progressive tachypnea develops. The anaerobic threshold can be measured directly from lactate concentration with good threshold detection from a log-log transformation of lactate and VO2. This threshold defines the VO2 at which the lactate/pyruvate ratio increases. As bicarbonate changes reciprocally with lactate, its measurement can also be used to estimate the lactate threshold. But most conveniently, changes in gas exchange caused by the physical-chemical event of buffering of lactic acid by bicarbonate can be used to detect the anaerobic threshold during exercise.