Institute of Sport Sciences, University of Lausanne, Lausanne, SWITZERLAND.
Department of Biological Sciences, University of Denver, Denver, CO.
Med Sci Sports Exerc. 2023 Feb 1;55(2):245-254. doi: 10.1249/MSS.0000000000003042. Epub 2022 Sep 22.
This study investigates the effects of normobaric hypoxia on repeated sprint exercise (RSE) with different balance between oxidative (phosphocreatine and oxidative pathway) and glycolytic contributions. Therefore, performance and psychophysiological responses were compared during RSE to exhaustion with the same exercise-to-rest ratio (1:2) but different sprint durations (5, 10, or 20 s) either in normoxic (RSN) or hypoxic (RSH; F io2 = 0.13) conditions.
On separate visits, 10 active participants completed in random order three cycling RSN (5:10; 10:20 and 20:40) and three similar RSH sessions to exhaustion. Vastus lateralis muscle oxygenation was recorded by near-infrared spectroscopy. Blood lactate concentration, limb and breathing discomfort, and ratings of perceived exertion were measured.
Total sprint number was smaller in hypoxia than in normoxia for 5:10 (20.8 ± 8.6 vs 14.7 ± 3.4; P = 0.014) and 10:20 (13.7 ± 6.3 vs 8.8 ± 2.5; P = 0.018) but not 20:40 (5.6 ± 1.9 vs 5.6 ± 2.5). The fatigue index was larger in hypoxia only for 5:10 (-43.5%, P < 0.001). Irrespective of condition, blood lactate concentration increased with the sprint duration with higher values for 20:40 than 5:10 (13.1 ± 2.7 vs 11.5 ± 2.2 mmoL·L -1 ; P = 0.027). Limb and breathing discomfort and ratings of perceived exertion did not differ in all RSE. Muscle oxygenation was mainly impacted by sprint duration (i.e., main effect of sprint duration on [HHb] min, [tHb] max, Δ[HHb], and Δ[tHb]) but not by hypoxia. The normoxia-to-hypoxia percentage decrease for total sprint number for 5:10 was correlated with the highest power output over 5 s ( R2 = 0.55; P = 0.013) and 10 s ( R2 = 0.53; P = 0.016).
Hypoxia impairs repeated sprint ability when the oxidative but not the glycolytic contribution is substantial. The oxidative-glycolytic balance, influenced partly by sprint duration, is key during repeated sprint in hypoxia.
本研究旨在探讨常压低氧对不同氧化（磷酸肌酸和氧化途径）和糖酵解贡献平衡的重复冲刺运动（RSE）的影响。因此，在相同的运动与休息比（1:2）但不同的冲刺持续时间（5、10 或 20 秒）下，在常氧（RSN）或低氧（RSH；F io2 = 0.13）条件下，比较了 RSE 至力竭时的运动表现和心理生理反应。
在单独的访问中，10 名活跃的参与者以随机顺序完成了三次 RSN（5:10；10:20 和 20:40）和三次类似的 RSH 至力竭的测试。通过近红外光谱法记录股外侧肌氧合。测量血乳酸浓度、肢体和呼吸不适以及感知用力程度。
与常氧相比，低氧时 5:10（20.8 ± 8.6 对 14.7 ± 3.4；P = 0.014）和 10:20（13.7 ± 6.3 对 8.8 ± 2.5；P = 0.018）的总冲刺次数较少，但 20:40 则没有（5.6 ± 1.9 对 5.6 ± 2.5）。只有在 5:10 时，低氧组的疲劳指数更大（-43.5%，P < 0.001）。无论条件如何，血乳酸浓度均随冲刺持续时间增加而增加，20:40 时的血乳酸浓度高于 5:10（13.1 ± 2.7 对 11.5 ± 2.2 mmoL·L-1；P = 0.027）。所有 RSE 中肢体和呼吸不适以及感知用力程度均无差异。肌肉氧合主要受冲刺持续时间的影响（即，冲刺持续时间对[HHb]min、[tHb]max、Δ[HHb]和Δ[tHb]的主要影响），而不是低氧的影响。5:10 时的总冲刺次数在常氧到低氧的百分比下降与 5 秒（R2 = 0.55；P = 0.013）和 10 秒（R2 = 0.53；P = 0.016）的最高功率输出相关。
当氧化贡献而不是糖酵解贡献较大时，低氧会损害重复冲刺能力。在低氧下进行重复冲刺时，氧化-糖酵解平衡受冲刺持续时间的部分影响，是关键。
