Jones A M, Carter H, Doust J H
Department of Exercise and Sport Science, Crewe and Alsager Faculty, the Manchester Metropolitan University, Alsager, United Kingdom.
Med Sci Sports Exerc. 1999 Sep;31(9):1299-306. doi: 10.1097/00005768-199909000-00011.
The purpose of this study was to assess the relationship between pulmonary VO2 and running speed over a range of exercise intensities. During constant-load cycle exercise above the lactate threshold (Tlac), it has been shown that VO2 does not attain a steady state within 3 min but continues to rise until either a delayed but elevated steady-state VO2 is attained or exhaustion occurs. Since this greater oxygen cost of exercise (V02 slow component) has only been demonstrated at discrete exercise intensities above Tlac, it was hypothesised that the onset of the VO2 slow component would coincide with Tlac during an incremental test if the stage durations were of sufficient length.
Five male subjects (mean +/- SD age 31 +/- 2 yr: VO2peak 60.1 +/- 5.8 mL x kg(-1) x min(-1)) performed four identical treadmill tests within an 8-d period. The tests involved the completion of six stages of 7-min duration. Running speed was increased by 0.5 km x h(-1) between stages. In the first test, fingertip capillary blood was sampled at the end of each stage for determination of Tlac. For all tests expired air was collected into Douglas bags from 3.0 to 3.75 min and from 6.0 to 6.75 min of each stage to determine any increase in V02 (deltaVO2) over the duration of the stage.
The mean deltaVO2 for each stage over the four tests was determined for each subject. Repeated measures ANOVA with post-hoc Tukey tests revealed a significant increase in deltaVO2 at running speeds above, but not below, Tlac.
The results of this study confirm the close association between the VO2 slow component and the onset of lactic acidosis and demonstrate alinearity in the VO2-exercise intensity relationship above Tlac for incremental treadmill exercise.
本研究旨在评估在一系列运动强度下肺摄氧量（VO₂）与跑步速度之间的关系。在高于乳酸阈（Tlac）的恒定负荷循环运动中，研究表明VO₂在3分钟内未达到稳定状态，而是持续上升，直到达到延迟但升高的稳定状态VO₂或出现疲劳。由于这种更大的运动氧耗（VO₂慢成分）仅在高于Tlac的离散运动强度下得到证实，因此假设在递增测试中，如果阶段持续时间足够长，VO₂慢成分的起始将与Tlac同时出现。
五名男性受试者（平均±标准差年龄31±2岁；VO₂峰值60.1±5.8 mL·kg⁻¹·min⁻¹）在8天内进行了四次相同的跑步机测试。测试包括完成六个7分钟的阶段。各阶段之间跑步速度以0.5 km·h⁻¹的幅度增加。在第一次测试中，在每个阶段结束时采集指尖毛细血管血样以测定Tlac。对于所有测试，在每个阶段的3.0至3.75分钟以及6.0至6.75分钟收集呼出气体到道格拉斯袋中，以确定该阶段持续时间内VO₂的任何增加（ΔVO₂）。
确定了每个受试者在四次测试中每个阶段的平均ΔVO₂。采用事后Tukey检验的重复测量方差分析显示，在高于但不低于Tlac的跑步速度下，ΔVO₂有显著增加。
本研究结果证实了VO₂慢成分与乳酸性酸中毒起始之间的密切关联，并证明了递增跑步机运动中高于Tlac时VO₂与运动强度关系的非线性。
