急性低氧暴露对台阶强度动态恒外阻力腿部伸展运动中神经肌肉和血液动力学反应的影响。

Impact of acute hypoxic exposure on neuromuscular and hemodynamic responses during step intensity dynamic constant external resistance leg extension exercise.

机构信息

Robbins College of Health and Human Sciences, Human & Environmental Physiology Laboratory, Baylor University, One Bear Place #97313, Waco, TX 76798, USA.

出版信息

J Electromyogr Kinesiol. 2024 Aug;77:102887. doi: 10.1016/j.jelekin.2024.102887. Epub 2024 May 15.

DOI:10.1016/j.jelekin.2024.102887

PMID:38761513

Abstract

OBJECTIVES

This study examined the effects of acute normoxic and hypoxic exposure on neuromuscular and hemodynamic physiological responses performed during dynamic step muscle actions.

METHODS

Thirteen recreationally active men (mean ± SD age: 21.2 ± 2.9 yrs) performed dynamic leg extensions unilaterally under Normoxic (FiO = 21 %) and Hypoxic (FiO = 13 %) conditions in a randomized order at 20 %, 40 %, 60 %, 80 %, and 100 % of their maximal strength. Electromyographic (EMG) amplitude, EMG frequency, (Oxygenated and Deoxygenated hemoglobin; Oxy, Deoxy, Total hemoglobin (Total), and skeletal muscle tissue oxygenation status (StO) were measured from the vastus lateralis during all contractions.

RESULTS

There were no detectable differences in the neuromuscular responses between normoxia and hypoxia for EMG amplitude (p = 0.37-0.74) and frequency (p = 0.17-0.83). For EMG amplitude there were general increases with intensity (p < 0.01-0.03). EMG frequency remained similar from 20% to 80% and then increased at 100 % effort (p = 0.02). There was no significant difference in patterns of responses for Oxy (p = 0.870) and Total (p = 0.200) between normoxia and hypoxia. StO (p = 0.028) decreased and Deoxy (p = 0.006) increased under hypoxia compared to normoxia during dynamic step muscle actions performed in a randomized order.

CONCLUSION

Unlike fatigue, acute hypoxemia in an unfatigued state does not impact the localized neuromuscular responses, but minimally impacts the hemodynamic responses.

摘要

目的

本研究旨在探讨急性常氧和低氧暴露对动态腿部伸展肌肉动作过程中神经肌肉和血液动力学生理反应的影响。

方法

13 名有休闲运动经验的男性（平均年龄±标准差：21.2±2.9 岁）在随机顺序下，在常氧（FiO₂=21%）和低氧（FiO₂=13%）条件下，以 20%、40%、60%、80%和 100%的最大力量分别进行单侧动态腿部伸展运动。在所有收缩过程中，从股外侧肌测量肌电图（EMG）幅度、EMG 频率、（氧合和去氧血红蛋白；Oxy、Deoxy、总血红蛋白（Total）和骨骼肌组织氧合状态（StO）。

结果

在常氧和低氧条件下，EMG 幅度（p=0.37-0.74）和频率（p=0.17-0.83）的神经肌肉反应没有明显差异。EMG 幅度随着强度的增加而普遍增加（p<0.01-0.03）。EMG 频率在 20%至 80%之间保持相似，然后在 100%的努力下增加（p=0.02）。在常氧和低氧条件下，Oxy（p=0.870）和 Total（p=0.200）的反应模式没有显著差异。与常氧相比，在随机顺序下进行的动态腿部肌肉动作中，低氧时 StO（p=0.028）降低，Deoxy（p=0.006）增加。