Davies Rosemary C, Eston Roger G, Poole David C, Rowlands Ann V, DiMenna Fred, Wilkerson Daryl P, Twist Craig, Jones Andrew M
School of Sport and Health Sciences, University of Exeter, St. Luke's Campus, Heavitree Rd., Exeter EX1 2LU, United Kingdom.
J Appl Physiol (1985). 2008 Nov;105(5):1413-21. doi: 10.1152/japplphysiol.90743.2008. Epub 2008 Aug 14.
Unaccustomed eccentric exercise has a profound impact on muscle structure and function. However, it is not known whether associated microvascular dysfunction disrupts the matching of O2 delivery (Qo2) to O2 utilization (Vo2). Near-infrared spectroscopy (NIRS) was used to test the hypothesis that eccentric exercise-induced muscle damage would elevate the muscle Qo2:Vo2 ratio during severe-intensity exercise while preserving the speed of the Vo2 kinetics at exercise onset. Nine physically active men completed "step" tests to severe-intensity exercise from an unloaded baseline on a cycle ergometer before (Pre) and 48 h after (Post) eccentric exercise (100 squats with a load corresponding to 70% of body mass). NIRS and breath-by-breath pulmonary Vo2 were measured continuously during the exercise tests and subsequently modeled using standard nonlinear regression techniques. There were no changes in phase II pulmonary Vo2 kinetics following the onset of exercise (time constant: Pre, 25 +/- 4 s; Post, 24 +/- 2 s; amplitude: Pre, 2.36 +/- 0.23 l/min; Post, 2.37 +/- 0.23 l/min; all P > 0.05). However, the primary (Pre, 14 +/- 3 s; Post, 19 +/- 3 s) and overall (Pre, 16 +/- 4 s; Post, 21 +/- 4 s) mean response time of the [HHb] response was significantly slower following eccentric exercise (P < 0.05). The slower [HHb] kinetics observed following eccentric exercise is consistent with an increased Qo2:Vo2 ratio during transitions to severe-intensity exercise. We propose that unchanged primary phase Vo2 kinetics are associated with an elevated Qo2:Vo2 ratio that preserves blood-myocyte O2 flux.
不习惯的离心运动对肌肉结构和功能有深远影响。然而，尚不清楚相关的微血管功能障碍是否会破坏氧气输送（Qo2）与氧气利用（Vo2）的匹配。近红外光谱（NIRS）被用于检验以下假设：离心运动诱导的肌肉损伤会在高强度运动期间提高肌肉Qo2:Vo2比值，同时在运动开始时保持Vo2动力学的速度。九名身体活跃的男性在离心运动（100次负重相当于体重70%的深蹲）前（Pre）和后48小时（Post），在自行车测力计上从无负荷基线完成了至高强度运动的“阶梯”测试。在运动测试期间连续测量NIRS和逐次呼吸的肺Vo2，随后使用标准非线性回归技术进行建模。运动开始后，II期肺Vo2动力学没有变化（时间常数：Pre，25±4秒；Post，24±2秒；幅度：Pre，2.36±0.23升/分钟；Post，2.37±0.23升/分钟；所有P>0.05）。然而，离心运动后，[HHb]反应的主要平均反应时间（Pre，14±3秒；Post，19±3秒）和总体平均反应时间（Pre，16±4秒；Post，21±4秒）显著减慢（P<0.05）。离心运动后观察到的较慢的[HHb]动力学与向高强度运动过渡期间Qo2:Vo2比值增加一致。我们提出，初级阶段Vo2动力学不变与升高的Qo2:Vo2比值相关，该比值可保持血液-心肌细胞氧气通量。
