Laboratoire des Sciences du Sport , Besançon, France ; Laboratoire d'Analyse de la Performance Sportive, Université de Pau, Département STAPS , Tarbes, France.
J Sports Sci Med. 2007 Dec 1;6(4):526-31. eCollection 2007.
Besides neuro-mechanical constraints, chemical or metabolic stimuli have also been proposed to interfere with the coordination between respiratory and locomotor rhythms. In the light of the conflicting data observed in the literature, this study aimed to assess whether acute hypoxia modifies the degree of coordination between respiratory and locomotor rhythms during rowing exercises in order to investigate competitive interactions between neuro-mechanical (movement) and chemical (hypoxia) respiratory drives. Nine male healthy subjects performed one submaximal 6-min rowing exercise on a rowing ergometer in both normoxia (altitude: 304 m) and acute hypoxia (altitude: 2877 m). The exercise intensity was about 40 % and 35 % (for normoxia and hypoxia conditions, respectively) of the individual maximal power output measured during an incremental rowing test to volitional exhaustion carried out in normoxia. Metabolic rate and minute ventilation were continuously collected throughout exercise. Locomotor movement and breathing rhythms were continuously recorded and synchronized cycle-by-cycle. The degree of coordination was expressed as a percentage of breaths starting during the same phase of the locomotor cycle. For a same and a constant metabolic rate, acute hypoxia did not influence significantly the degree of coordination (mean ± SEM, normoxia: 20.0 ± 6.2 %, hypoxia: 21.3 ± 11.1 %, p > 0.05) while ventilation and breathing frequency were significantly greater in hypoxia. Our results may suggest that during rowing exercise at a moderate metabolic load, neuro-mechanical locomotion-linked respiratory stimuli appear "stronger "than peripheral chemoreceptors- linked respiratory stimuli induced by hypoxia, in the context of our study. Key pointsChanges in breathing frequency and ventilation induced by altitude have no effect on the degree of coordination between locomotor and breathing rhythms during moderate rowing exercise.During moderate rowing exercise in hypoxia, the neuro-mechanical drives still dominate over chemoreceptive stimuli.These above statements have to be taken carefully because it might be quite different during activities where the coupling between locomotor and breathing rhythms is less constrained (e.g., running, cycling).
除了神经机械限制外，化学或代谢刺激也被提出会干扰呼吸和运动节律之间的协调。鉴于文献中观察到的相互矛盾的数据，本研究旨在评估急性缺氧是否会改变划桨运动期间呼吸和运动节律之间的协调程度，以研究神经机械（运动）和化学（缺氧）呼吸驱动之间的竞争相互作用。9 名健康男性受试者在划船测功仪上分别在常氧（海拔 304 米）和急性缺氧（海拔 2877 米）条件下进行一次最大 6 分钟的亚最大强度划船运动。运动强度约为个体最大输出功率增量划船测试至常氧自愿衰竭测量值的 40%和 35%（分别用于常氧和缺氧条件）。运动过程中持续收集代谢率和分钟通气量。连续记录和同步运动和呼吸节律的周期到周期。协调程度用呼吸开始于运动周期相同相位的百分比表示。对于相同和恒定的代谢率，急性缺氧不会显著影响协调程度（平均值±SEM，常氧：20.0±6.2%，缺氧：21.3±11.1%，p>0.05），而通气量和呼吸频率在缺氧时显著增加。我们的结果可能表明，在适度代谢负荷下进行划船运动时，神经机械运动相关的呼吸刺激在我们的研究背景下似乎比由缺氧引起的外周化学感受器相关的呼吸刺激“更强”，在我们的研究背景下，神经机械运动相关的呼吸刺激比由缺氧引起的外周化学感受器相关的呼吸刺激“更强”。关键点在中等划船运动期间，海拔引起的呼吸频率和通气变化对运动和呼吸节律之间的协调程度没有影响。在低氧条件下进行中等强度的划船运动时，神经机械驱动仍然支配着化学感受刺激。这些陈述必须谨慎对待，因为在运动和呼吸节律耦合受限制较少的活动中（例如跑步、骑自行车），情况可能大不相同。
