Athlete Health and Research Performance Center, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar.
Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland.
Eur J Appl Physiol. 2017 Nov;117(11):2171-2179. doi: 10.1007/s00421-017-3705-y. Epub 2017 Aug 29.
We manipulated the inspired oxygen fraction (FiO) to examine the effects of physiological perturbations on exercise-related sensations and the neural drive of the quadriceps during repeated, brief, maximal cycle sprints.
Nine active males completed a repeated sprint cycle protocol (10 × 4-s maximal sprints with 30 s of passive recovery) in normoxia (NM; FiO 0.21) and severe normobaric hypoxia (HY; FiO 0.13). Peak power, quadriceps Root Mean Squared electromyography (RMS EMG), physiological (heart rate, arterial oxygen saturation, blood lactate concentration) and perceptual responses were recorded.
The 10 sprints in HY were associated with lower arterial oxygen saturation values compared to NM [80.7 ± 0.9 vs. 95.6 ± 0.6%; P < 0.001; effect size (ES) = 0.98], higher blood lactate values (11.9 ± 0.4 vs. 9.9 ± 0.9 mmol L; P = 0.05; ES = 0.36), and greater exercise-related sensations (~36%; P < 0.001; ES > 0.47). Mean power for sprints 1-10 were lower (-13 ± 3%; P = 0.001; ES = 0.79), and sprint decrement was more pronounced in HY compared to NM (21.4 ± 3.7 vs. 13.2 ± 2.7%; P = 0.003). There was a 17% decrease in RMS EMG activity from the first to the last sprint (P < 0.001; ES = 0.65), independent of condition (P = 0.597; ES = 0.04).
Despite severe hypoxia exacerbating both physiological and perceptual perturbations, the performance decrement observed during the repeated sprint protocol did not coincide with an accentuated decline in RMS EMG activity. These data suggest that higher-than-normal exercise-related sensations or perceptions coincide with fatigue during repeated sprinting, independent of changes in neural drive, when the task characteristics are known beforehand.
我们通过调整吸入氧气分数（FiO），研究生理干扰对重复短暂最大自行车冲刺过程中与运动相关的感觉和股四头肌神经驱动的影响。
9 名男性运动员在常氧（NM；FiO 0.21）和严重常压缺氧（HY；FiO 0.13）条件下完成重复冲刺自行车测试方案（10 次 4 秒最大冲刺，30 秒被动恢复）。记录峰值功率、股四头肌均方根肌电（RMS EMG）、生理（心率、动脉血氧饱和度、血乳酸浓度）和感知反应。
HY 组的 10 次冲刺与 NM 组相比，动脉血氧饱和度值较低[80.7±0.9 比 95.6±0.6%；P<0.001；效应量（ES）=0.98]，血乳酸值较高（11.9±0.4 比 9.9±0.9mmol·L-1；P=0.05；ES=0.36），与运动相关的感觉更强烈（~36%；P<0.001；ES>0.47）。第 1-10 次冲刺的平均功率较低（-13±3%；P=0.001；ES=0.79），与 NM 相比，HY 组的冲刺衰减更明显（21.4±3.7 比 13.2±2.7%；P=0.003）。从第一次冲刺到最后一次冲刺，RMS EMG 活动减少了 17%（P<0.001；ES=0.65），与条件无关（P=0.597；ES=0.04）。
尽管严重缺氧会加剧生理和感知干扰，但在重复冲刺测试方案中观察到的运动表现下降与 RMS EMG 活动的明显下降并不一致。这些数据表明，在事先了解任务特征的情况下，当运动相关的感觉或感知高于正常水平时，会与重复冲刺时的疲劳同时发生，而与神经驱动的变化无关。
