School of Sport and Health Sciences, St. Luke's Campus, University of Exeter, Heavitree Road, Exeter, Devon EX1 2LU, UK.
Respir Physiol Neurobiol. 2010 Sep 30;173(2):138-45. doi: 10.1016/j.resp.2010.07.005. Epub 2010 Jul 21.
We used near-infrared spectroscopy (NIRS) to test the hypothesis that body position alters the sigmoidal response profile of muscle fractional O(2) extraction (estimated using deoxy[Hb+Mb]) during incremental cycle exercise. Seven male subjects (mean±SD age 32±13 years) completed a ramp incremental cycling test to exhaustion (30W/min) in both the supine and upright body positions. The sigmoidal (as opposed to hyperbolic) model that provided the better fit to deoxy[Hb+Mb] data during upright cycling was also present for the supine response; however, the slope of the sigmoid was increased (upright: 0.052±0.012 vs. supine: 0.090±0.036%⋅%P(peak)(-1); P<0.05) and a plateau occurred at a lower work rate (upright: 83±8 vs. supine: 68±19%P(peak)(-1); P<0.05) during supine exercise. These changes occurred in the absence of a leftward shift of the sigmoid. We also found a significantly greater deltaV(O)₂/deltaW slope above compared to below gas exchange threshold (GET) for both conditions (upright: 9.8±0.5 vs. 8.2±0.9; supine: 10.7±0.9 vs. 8.0±0.8) and for supine compared to upright cycling above GET. These findings suggest that the supine posture affects O₂ extraction and V(O)₂ kinetics to a greater extent as work rate progresses during ramp incremental exercise.
我们使用近红外光谱（NIRS）来检验以下假说，即身体姿势会改变肌肉部分氧摄取率（用去氧[Hb+Mb]来估算）在递增式循环运动中的曲线响应形态。7 名男性被试（平均年龄±标准差为 32±13 岁）在仰卧位和直立位两种姿势下完成了递增式自行车测试直至力竭（30W/min）。在直立位自行车运动中，与双曲线模型相比，去氧[Hb+Mb]数据更符合曲线模型；然而，曲线的斜率增加（直立位：0.052±0.012 比仰卧位：0.090±0.036%⋅%P(peak)(-1)；P<0.05），并且在仰卧位运动中，平台期出现在更低的工作率（直立位：83±8 比仰卧位：68±19%P(peak)(-1)；P<0.05）。这些变化的发生并未导致曲线向左移位。我们还发现，与仰卧位相比，在直立位自行车运动中，在高于和低于气体交换阈值（GET）时，deltaV(O)₂/deltaW 斜率显著更大（直立位：9.8±0.5 比 8.2±0.9；仰卧位：10.7±0.9 比 8.0±0.8），并且在高于 GET 时，仰卧位比直立位自行车运动中 deltaV(O)₂/deltaW 斜率更大。这些发现表明，在递增式循环运动中，随着工作率的增加，仰卧位会更大程度地影响氧摄取和 V(O)₂动力学。
