Department of Exercise Science and Outdoor Recreation, Utah Valley University, Orem, UT 84058, USA.
Department of Exercise Science, Fairmont State University, Fairmont, WV 26554, USA.
Int J Environ Res Public Health. 2022 Jul 26;19(15):9139. doi: 10.3390/ijerph19159139.
The intensity of large muscle mass exercise declines at altitude due to reduced oxygen delivery to active muscles. The purpose of this investigation was to determine if the greater limb blood flow during single-leg cycling prevents the reduction in tissue oxygenation observed during traditional double-leg cycling in hypoxic conditions. Ten healthy individuals performed bouts of double and single-leg cycling (4, four-minute stages at 50−80% of their peak oxygen consumption) in hypoxic (15% inspired O2) and normoxic conditions. Heart rate, mean arterial pressure, femoral blood flow, lactate, oxygenated hemoglobin, total hemoglobin, and tissue saturation index in the vastus lateralis were recorded during cycling tests. Femoral blood flow (2846 ± 912 mL/min) and oxygenated hemoglobin (−2.98 ± 3.56 au) during single-leg cycling in hypoxia were greater than double-leg cycling in hypoxia (2429 ± 835 mL/min and −6.78 ± 3.22 au respectively, p ≤ 0.01). In addition, tissue saturation index was also reduced in the double-leg hypoxic condition (60.2 ± 3.1%) compared to double-leg normoxic (66.0 ± 2.4%, p = 0.008) and single-leg hypoxic (63.3 ± 3.2, p < 0.001) conditions. These data indicate that while at altitude, use of reduced muscle mass exercise can help offset the reduction in tissue oxygenation observed during larger muscle mass activities allowing athletes to exercise at greater limb/muscle specific intensities.
由于向活跃肌肉输送的氧气减少，大肌肉群运动的强度在高海拔地区会下降。本研究的目的是确定在缺氧条件下，单腿循环时较大的肢体血流量是否可以防止在传统的双腿循环中观察到的组织氧合减少。10 名健康个体在缺氧（15%吸入 O2）和常氧条件下进行了双腿和单腿循环（4 个 4 分钟阶段，分别为峰值耗氧量的 50-80%）。在循环测试期间记录了心率、平均动脉压、股动脉血流量、乳酸、氧合血红蛋白、总血红蛋白和股外侧肌的组织饱和度指数。单腿循环在缺氧时的股动脉血流量（2846 ± 912 mL/min）和氧合血红蛋白（-2.98 ± 3.56 au）大于缺氧时的双腿循环（分别为 2429 ± 835 mL/min 和-6.78 ± 3.22 au，p ≤ 0.01）。此外，与双腿常氧（66.0 ± 2.4%，p = 0.008）和单腿缺氧（63.3 ± 3.2，p < 0.001）条件相比，双腿缺氧条件下的组织饱和度指数也降低（60.2 ± 3.1%）。这些数据表明，在高海拔地区，使用较小肌肉群运动可以帮助抵消较大肌肉群活动中观察到的组织氧合减少，从而使运动员能够以更大的肢体/肌肉特定强度进行运动。
