Skeletal muscle biochemical origin of exercise intensity domains and their relation to whole-body V̇O2 kinetics.
Skeletal muscle biochemical origin of exercise intensity domains and their relation to whole-body V̇O2 kinetics.
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DOI：
10.1042/bsr20220798
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发表时间：
2022-08-31
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4
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本文介绍了运动强度域的生化骨骼肌内基础：中等（M），重（H），非常重（VH）和严重（S）。阈值起源是由一个“Pi双阈值”机制介导的，该机制假设：（1）当无机磷（Pi）超过临界值（Picrit）时，开始额外的ATP使用，这是肌肉V ~ O2和代谢慢成分的基础;（2）当Pi达到峰值（Pipeak）时，由于疲劳而终止运动;（3）Pi的增加与额外ATP用量的增加相互促进，形成正反馈。M/H和H/VH边界由与Picrit和Pipeak相关的Pi离子动力学定义。ATP利用活性的值，成比例的功率输出（PO），为M/H，H/VH和VH/S的边界是最低的未经训练的肌肉和最高的训练有素的肌肉。M/H和H/VH边界（或“H空间”）之间的代谢范围随着肌肉训练而减小，而H/VH和VH/S边界（或“VH空间”）之间的差异仅微弱地依赖于训练状态。肌肉V ~ O_2慢成分的绝对值在M运动中不存在，在H运动中随PO的增加而逐渐升高，达到最大值，在VH和S运动中随PO的增加而降低。模拟未经训练，体力活动和训练有素的肌肉表明，肌肉M/H边界不需要相同的全身M/H边界确定的肺V ~ 2 O ~ 2的动力学和血乳酸，同时表明，生化起源的H/VH边界驻留在骨骼肌和对应于全身的临界功率。
This article presents the biochemical intra-skeletal-muscle basis of exercise intensity domains: moderate (M), heavy (H), very heavy (VH) and severe (S). Threshold origins are mediated by a ‘Pi double-threshold’ mechanism of muscle fatigue, which assumes (1) additional ATP usage, underlying muscle V̇O2 and metabolite slow components, is initiated when inorganic phosphate (Pi) exceeds a critical value (Picrit); (2) exercise is terminated because of fatigue, when Pi reaches a peak value (Pipeak); and (3) the Pi increase and additional ATP usage increase mutually stimulate each other forming a positive feedback. M/H and H/VH borders are defined by Pi on-kinetics in relation to Picrit and Pipeak. The values of the ATP usage activity, proportional to power output (PO), for the M/H, H/VH and VH/S borders are lowest in untrained muscle and highest in well-trained muscle. The metabolic range between the M/H and H/VH border (or ‘H space’) decreases with muscle training, while the difference between the H/VH and VH/S border (or ‘VH space’) is only weakly dependent on training status. The absolute magnitude of the muscle V̇O2 slow-component, absent in M exercise, rises gradually with PO to a maximal value in H exercise, and then decreases with PO in VH and S exercise. Simulations of untrained, physically active and well-trained muscle demonstrate that the muscle M/H border need not be identical to the whole-body M/H border determined from pulmonary V̇O2 on-kinetics and blood lactate, while suggesting that the biochemical origins of the H/VH border reside within skeletal muscle and correspond to whole-body critical power.