Azevedo Rafael D A, J E Béjar Saona, Inglis Erin Calaine, Iannetta Danilo, Murias Juan M
Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada.
Physiol Rep. 2020 Jun;8(12):e14478. doi: 10.14814/phy2.14478.
This study investigated the effect of reduced inspired fraction of O (FiO ) in the correspondence between the respiratory compensation point (RCP) and the breakpoint in the near-infrared spectroscopy-derived deoxygenated hemoglobin signal ([HHb] ) during a ramp-incremental (RI) test to exhaustion. Eleven young males performed, on two separated occasions, a RI test either in normoxia (NORM, FiO = 20.9%) or hypoxia (HYPO, FiO = 16%). Oxygen uptake ( O ), and [HHb] signal from the vastus lateralis muscle were continuously measured. Peak O (2.98 ± 0.36 vs. 3.39 ± 0.26 L min ) and PO (282 ± 29 vs. 310 ± 19 W) were lower in HYPO compared to NORM condition, respectively. The O and PO associated with RCP and [HHb] were lower in HYPO (2.35 ± 0.24 and 2.34 ± 0.26 L min ; 198 ± 37 and 197 ± 30 W, respectively) when compared to NORM (2.75 ± 0.26 and 2.75 ± 0.28 L min ; 244 ± 29 and 241 ± 28 W, respectively) (p < .05). Within the same condition, the O and PO associated with RCP and [HHb] were not different (p > .05). Bland-Altman plots mean average errors between RCP and [HHb] were not different from zero in HYPO (0.01 L min and 1.1 W) and NORM (0.00 L min and 3.6 W) conditions. The intra-individual changes between thresholds associated with O and PO in HYPO from NORM were strongly correlated (r = .626 and 0.752, p < .05). Therefore, breathing a lower FiO during a RI test resulted in proportional reduction in the RCP and the [HHb] in terms of O and PO, which further supports the notion that these physiological responses may arise from similar metabolic changes reflecting a common phenomenon.
本研究调查了在递增负荷（RI）至力竭测试期间，降低吸入氧分数（FiO₂）对呼吸补偿点（RCP）与近红外光谱衍生的脱氧血红蛋白信号（[HHb]）断点之间对应关系的影响。11名年轻男性在两个不同时间段分别在常氧（NORM，FiO₂ = 20.9%）或低氧（HYPO，FiO₂ = 16%）条件下进行RI测试。持续测量外侧股四头肌的摄氧量（VO₂）和[HHb]信号。与常氧条件相比，低氧条件下的峰值VO₂（2.98 ± 0.36对3.39 ± 0.26 L·min⁻¹）和功率峰值（282 ± 29对310 ± 19 W）更低。与常氧（2.75 ± 0.26和2.75 ± 0.28 L·min⁻¹；244 ± 29和241 ± 28 W）相比，低氧条件下与RCP和[HHb]相关的VO₂和功率峰值更低（分别为2.35 ± 0.24和2.34 ± 0.26 L·min⁻¹；198 ± 37和197 ± 30 W）（p < 0.05）。在相同条件下，与RCP和[HHb]相关的VO₂和功率峰值无差异（p > 0.05）。在低氧（VO₂为0.01 L·min⁻¹和功率为1.1 W）和常氧（VO₂为0.00 L·min⁻¹和功率为3.6 W）条件下，RCP和[HHb]之间的Bland-Altman图平均误差与零无差异。低氧条件下相对于常氧条件，与VO₂和功率峰值相关的阈值的个体内变化高度相关（r = 0.626和0.752，p < 0.05）。因此，在RI测试期间呼吸较低的FiO₂会导致RCP和[HHb]在VO₂和功率峰值方面成比例降低，这进一步支持了这些生理反应可能源于反映共同现象的相似代谢变化这一观点。
