Wilkerson Daryl P, Jones Andrew M
School of Sport and Health Sciences, University of Exeter, St. Luke's Campus, Heavitree Road, Exeter EX1 2LU, United Kingdom.
Respir Physiol Neurobiol. 2007 May 14;156(2):203-11. doi: 10.1016/j.resp.2006.09.008. Epub 2006 Oct 7.
We hypothesised that initiating heavy-intensity exercise from an elevated baseline metabolic rate would result in slower Phase II O2 uptake V(O2) kinetics and a greater overall 'gain' in V(O2) per unit increase in work rate. Seven healthy males performed a series of like-transitions on a cycle ergometer: (1) from light exercise to 'moderate' exercise (80% of the gas exchange threshold, GET; L-->M); (2) from light exercise to 'heavy' exercise (40% of the difference between GET and V(O2) peak; L-->H); (3) from moderate exercise to heavy exercise (M-->H). The Phase II time constant (tau) was significantly (P<0.01) greater in the M-->H condition (48+/-11 s) compared to the L-->M and L-->H conditions (26+/-6 s versus 27+/-4 s, respectively). Moreover, the end-exercise 'gain' values were significantly different between the three conditions (L-->M, 8.1+/-0.7 mL min-1 W-1; L-->H, 9.7+/-0.4 mL min-1 W-1; M-->H, 10.7+/-0.7 mL min-1 W-1; P<0.05). This 'non-linearity' in the pulmonary V(O2) response to exercise might be attributed, at least in part, to differences in the metabolic properties of the muscle fibres recruited in the abrupt transition from a lower to a higher work rate.
我们假设，从升高的基础代谢率开始进行高强度运动，将导致第二阶段氧气摄取量（V(O2)）动力学变慢，并且每单位工作率增加时V(O2)的总体“增加量”更大。七名健康男性在自行车测力计上进行了一系列类似的转换：（1）从轻运动转换为“中等强度”运动（气体交换阈值的80%，GET；L→M）；（2）从轻运动转换为“高强度”运动（GET与V(O2)峰值之差的40%；L→H）；（3）从中等强度运动转换为高强度运动（M→H）。与L→M和L→H条件（分别为26±6秒和27±4秒）相比，M→H条件下的第二阶段时间常数（tau）显著更大（P<0.01）（48±11秒）。此外，三种条件下运动结束时的“增加量”值存在显著差异（L→M，8.1±0.7 mL min-1 W-1；L→H，9.7±0.4 mL min-1 W-1；M→H，10.7±0.7 mL min-1 W-1；P<0.05）。肺部V(O2)对运动反应的这种“非线性”可能至少部分归因于在从较低工作率突然转换到较高工作率时所募集的肌纤维代谢特性的差异。
