研究在递增强度运动过程中人体骨骼肌内氧合血红蛋白(HbO2)含量相对变化的拐点与呼吸商拐点, 比较两者在时间上出现的先后次序及规律, 分析它们不同步的生理机制。选取赛艇专项运动员12名为被试者, 在赛艇测功仪(CONCEPT Ⅱ)上做等级性递增强度运动, 起始功率为50 W, 此后每3 min增加50 W直至力竭。运动中利用近红外三波长便携式肌氧监测仪监测被试者股四头肌中HbO2含量相对变化, 并通过MAX-Ⅱ心肺功能仪同步记录其摄氧量, 包括氧摄入量(VO2)和二氧化碳呼出量(VCO2)。呼吸商拐点相对于HbO2相对变化拐点有一个延迟效应。结论：近红外光谱肌氧监测系统可以比呼吸系统更及时的反应运动员在运动中的无氧工作状态。这为利用肌氧监测系统测定HbO2变化来推测呼吸商拐点提供了有力的佐证, 这将有可能提供新的摄氧量测定方法。

The relative change between inflection points of respiratory quotient (RQ) and HbO2 in skeletal muscle during the process of increased intensity sports is investigated. The occurrence priority and interval regularity of the two based on time is compared, and the physiological mechanism of synchronisms is analyzed. 12 rowing athlete candidates are chosen to test to do increased intensity sports on dynamometer (CONCEPT Ⅱ). The output power of initial load is 50 W, and then increased by 50 W every 3 min until exhaustive. The relative changes of HbO2 in Quadriceps by near-infrared spectroscopy (NIRS) during sports are monitored. Simultaneously the oxygen uptake of candidates in sports is determined and recorded, including the intake of oxygen (VO2) and exhaled volume of carbon dioxide (VCO2) by the Cardiopulmonary Function Instrument MAX-Ⅱ. The inflection point of RQ is relatively changing to ΔHbO2. That means there is a time delay in RQ. The delay in VO2 and VCO2 relative to HbO2, which is affirmed in the single-factor variance analysis test, is do exist. During increased intensity sports, the respiratory quotient changes regularly accompanied with the inflection point, and content of muscle oxygen (ΔHbO2) in quadriceps changes regularly with unconventional inflection point which might denote that of respiratory quotient. Inflection point of respiratory quotient has a regular delay time relative to that of ΔHbO2. The phenomenon provides powerful evidence for us to speculate inflection point of respiratory quotient by measuring ΔHbO2 in Muscle-Oxygen Monitoring System. It may provide new methods to measure oxygen uptake.