结论:氧气输送被认为与低于临界力的运动需求紧密耦合,因为增加氧气输送不会增加氧气吸收速率。尚不清楚在低于临界功率的小肌肉量运动中,氧气输送的“正常”调节对于兴奋-收缩耦合是否是最佳的。在这里,我们在人类中表明,增加氧气输送超过“正常”可以改善激发-收缩耦合。这些结果表明,在高强度运动领域,氧气输送与代谢需求的“正常”匹配对于肌肉兴奋-收缩耦合不是最佳的。因此,运动肌肉中血管调节的性质是,它不支持兴奋-收缩耦合的最佳灌注。
UNASSIGNED:氧气输送被视为与临界功率以下运动中的需求紧密耦合,因为增加氧气输送不会增加VO2。然而,目前尚不清楚,在大强度域中,对小肌肉量运动的氧气输送的“正常”调整是否最适合兴奋-收缩耦合。20名参与者(10名女性)远程骨骼肌(即,在收缩力(实验模型1)和以肌肉激活为目标(实验模型2)的节律性前臂握力运动期间,胫骨前肌)转移(高灌注状态)或未(对照状态)激活4分钟。对来自两个实验模型的组合数据完成分析。在远程骨骼肌代谢反射激活30秒后,平均动脉血压,前臂血流,和肌肉氧合增加,并保持增加,直到metaboreflex停药。当氧气输送量提高时,肌肉激活与收缩力的比率得到改善。在metaboreflex中断后,前臂氧气输送和肌肉激活和收缩力比率迅速(在30秒内)恢复到对照水平。这些发现表明,(a)metaboreflex可有效增加前臂肌肉的氧气输送和氧合,(b)随着氧气输送的增加,肌肉激活与收缩力的比率得到改善,和(C)在重运动强度领域,氧气输送与代谢需求的正常匹配对于肌肉兴奋-收缩耦合不是最佳的。这些结果表明,运动肌肉中血管调节的性质是,它不支持兴奋-收缩耦合的最佳灌注。摘要图例目的:检验以下假设:针对肌肉收缩功能优化了氧气输送的“正常”调节。
方法:在20名参与者(10名女性)中,远程骨骼肌(即,在收缩力和针对有节奏的前臂手握运动的肌肉激活过程中,胫骨前)代谢反射被激活(高灌注状态)或未被激活(控制状态)持续4分钟。
结果:在高灌注条件下,随着血流量超过“正常”,收缩力与肌肉激活的比率迅速提高,然后在恢复正常血流量条件下,该比率迅速恢复到对照水平。
结论:运动肌肉中血管调节的性质是它不支持兴奋-收缩耦合的最佳灌注。本文受版权保护。保留所有权利。
Oxygen delivery is viewed as tightly coupled to demand in exercise below critical power because increasing oxygen delivery does not increase V O 2 ${V_{{O_2}}}$ . However, whether the \'normal\' adjustment of oxygen delivery to small muscle mass exercise in the heavy intensity domain is optimal for excitation-contraction coupling is currently unknown. In 20 participants (10 female), a remote skeletal muscle (i.e. tibialis anterior) metaboreflex was (Hyperperfusion condition) or was not (Control condition) activated for 4 min during both force of contraction (experimental model 1) and muscle activation-targeted (experimental model 2) rhythmic forearm handgrip exercise. Analysis was completed on the combined data from both experimental models. After 30 s of remote skeletal muscle metaboreflex activation, mean arterial blood pressure, forearm blood flow and muscle oxygenation were increased and remained increased until metaboreflex discontinuation. While oxygen delivery was elevated, the muscle activation to force of contraction ratio was improved. Upon metaboreflex discontinuation, forearm oxygen delivery and the muscle activation and force of contraction ratio rapidly (within 30 s) returned to control levels. These findings demonstrate that (a) the metaboreflex was effective at increasing forearm muscle oxygen delivery and oxygenation, (b) the muscle activation to force of contraction ratio was improved with increased oxygen delivery, and (c) in the heavy exercise intensity domain, the normal matching of oxygen delivery to metabolic demand is not optimal for muscle excitation-contraction coupling. These results suggest that the nature of
vasoregulation in exercising muscle is such that it does not support optimal perfusion for excitation-contraction coupling. KEY POINTS: Oxygen delivery is viewed as tightly coupled to demand in exercise below critical power because increasing oxygen delivery does not increase the rate of oxygen uptake. Whether the \'normal\' adjustment of oxygen delivery in small muscle mass exercise below critical power is optimal for excitation-contraction coupling is not known. Here we show in humans that increasing oxygen delivery above \'normal\' improves excitation-contraction coupling. These results suggest that, in the heavy exercise intensity domain, the \'normal\' matching of oxygen delivery to metabolic demand is not optimal for muscle excitation-contraction coupling. Therefore, the nature of
vasoregulation in exercising muscle is such that it does not support optimal perfusion for excitation-contraction coupling.