Inglis Erin Calaine, Iannetta Danilo, Murias Juan M
Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.
Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
Am J Physiol Regul Integr Comp Physiol. 2017 Dec 1;313(6):R723-R729. doi: 10.1152/ajpregu.00261.2017. Epub 2017 Sep 20.
This study aimed to examine, at the level of the active muscles, whether the plateau in oxygen (O) extraction normally observed near the end of a ramp incremental (RI) exercise test to exhaustion is caused by the achievement of an upper limit in O extraction. Eleven healthy men (27.3 ± 3.0 yr, 81.6 ± 8.1 kg, 183.9 ± 6.3 cm) performed a RI cycling test to exhaustion. O extraction of the vastus lateralis (VL) was measured continuously throughout the test using the near-infrared spectroscopy (NIRS)-derived deoxygenated hemoglobin [HHb] signal. A leg blood flow occlusion was performed at rest (LBF) and immediately after the RI test (LBF). The [HHb] values during the resting occlusion (108.1 ± 21.7%; LBF) and the peak values during exercise (100 ± 0%; [HHb]) were significantly greater than those observed at baseline (0.84 ± 10.6% at and 0 ± 0% at ) ( < 0.05). No significant difference was found between LBF and [HHb] ( > 0.05) or between the baseline measurements ( > 0.05). [HHb] values at LBF (130.5 ± 19.7%) were significantly greater than all other time points ( < 0.05). These results support the existence of an O extraction reserve in the VL muscle at the end of a RI cycling test and suggest that the observed plateau in the [HHb] signal toward the end of a RI test is not representative of an upper limit in O extraction.
本研究旨在从活跃肌肉层面，探究在递增负荷运动试验接近疲劳终点时通常观察到的氧（O）摄取平台期，是否是由于达到了氧摄取上限所致。11名健康男性（年龄27.3±3.0岁，体重81.6±8.1千克，身高183.9±6.3厘米）进行了递增负荷骑行试验直至疲劳。在整个试验过程中，使用近红外光谱（NIRS）得出的脱氧血红蛋白[HHb]信号连续测量股外侧肌（VL）的氧摄取。在静息时（LBF）和递增负荷试验后立即进行腿部血流阻断（LBF）。静息阻断期间的[HHb]值（108.1±21.7%；LBF）和运动期间的峰值（100±0%；[HHb]）显著高于基线时观察到的值（静息时为0.84±10.6%，运动峰值时为0±0%）（P<0.05）。LBF时的[HHb]值与运动峰值时的[HHb]值之间无显著差异（P>0.05），基线测量值之间也无显著差异（P>0.05）。LBF时的[HHb]值（130.5±19.7%）显著高于所有其他时间点（P<0.05）。这些结果支持在递增负荷骑行试验结束时VL肌肉中存在氧摄取储备，并表明在递增负荷试验接近尾声时观察到的[HHb]信号平台期并不代表氧摄取上限。
