Thigh muscle activation distribution and pulmonary VO2 kinetics during moderate, heavy, and very heavy intensity cycling exercise in humans
Thigh muscle activation distribution and pulmonary VO2 kinetics during moderate, heavy, and very heavy intensity cycling exercise in humans
复制标题
DOI：
10.1152/ajpregu.00028.2007
复制
发表时间：
2007-08-01
影响因子：
2.8
通讯作者：
Fukuba, Yoshiyuki
中科院分区：
文献类型：
--
作者：
Endo, Masako Yamaoka;Kobayakawa, Mayumi;Fukuba, Yoshiyuki
在超乳酸阈（supra-LT）运动中，氧摄取（Vo（2））慢成分的机制知之甚少。有证据表明，Vo（2）慢成分可能是由运动过程中进行性肌肉募集引起的。因此，我们检查了腿部肌肉激活模式[来自磁共振图像的横向弛豫时间（T2）]是否与超LT Vo（2）动力学参数相关。11名受试者在中等强度（80%LT）、重强度（LT和临界功率之间的70%; CP）和非常重强度（CP以上的7%）下进行6分钟踏车测力，并逐呼吸测量肺Vo（2）。在休息时和运动3分钟和6分钟后，对10块腿部肌肉的T2进行了评估。在中度运动，9块肌肉达到稳定状态T2 3分钟，只有在股内侧肌T2进一步增加6分钟后。在剧烈运动，T2在整个股肌组增加3分钟和6分钟之间，和额外的增加T2被认为是在大收肌和股薄肌在此期间的非常繁重的运动。Vo（2）慢成分随运动强度的增加而增加（在中等运动期间功能为零）。随着超LT运动的进行，T2的分布更加多样化：在3分钟和6分钟的剧烈运动之间，T2方差（ms）从3.6 +/- 0.2增加到6.5 +/- 1.7，在非常剧烈的运动中，从5.5 +/- 0.8增加到12.3 +/- 5.4（休息= 3.1 +/- 0.6）。T2分布与Vo（2）慢成分的幅度显著相关（P < 0.05）。这些数据与Vo（2）慢成分是在超LT运动期间进行性肌肉募集的表达的观点一致。
The mechanisms underlying the oxygen uptake (Vo(2)) slow component during supra-lactate threshold (supra-LT) exercise are poorly understood. Evidence suggests that the Vo(2) Slow component may be caused by progressive muscle recruitment during exercise. We therefore examined whether leg muscle activation patterns [from the transverse relaxation time (T2) of magnetic resonance images] were associated with supra-LT Vo(2) kinetic parameters. Eleven subjects performed 6-min cycle ergometry at moderate (80% LT), heavy (70% between LT and critical power; CP), and very heavy (7% above CP) intensities with breath-by-breath pulmonary Vo(2) measurement. T2 in 10 leg muscles was evaluated at rest and after 3 and 6 min of exercise. During moderate exercise, nine muscles achieved a steady-state T2 by 3 min; only in the vastus medialis did T2 increase further after 6 min. During heavy exercise, T2 in the entire vastus group increased between minutes 3 and 6, and additional increases in T2 were seen in adductor magnus and gracilis during this period of very heavy exercise. The Vo(2) slow component increased with increasing exercise intensity (being functionally zero during moderate exercise). The distribution of T2 was more diverse as supra-LT exercise progressed: T2 variance (ms) increased from 3.6 +/- 0.2 to 6.5 +/- 1.7 between 3 and 6 min of heavy exercise and from 5.5 +/- 0.8 to 12.3 +/- 5.4 in very heavy exercise (rest = 3.1 +/- 0.6). The T2 distribution was significantly correlated with the magnitude of the Vo(2) slow component (P < 0.05). These data are consistent with the notion that the Vo(2) slow component is an expression of progressive muscle recruitment during supra-LT exercise.