Muscle contraction-blood flow interactions during upright knee extension exercise in humans
Muscle contraction-blood flow interactions during upright knee extension exercise in humans
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DOI：
10.1152/japplphysiol.00219.2004
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发表时间：
2005-04-01
影响因子：
3.3
通讯作者：
Barstow, TJ
中科院分区：
文献类型：
--
作者：
Lutjemeier, BJ;Miura, A;Barstow, TJ
为了测试肌肉泵效应在稳定状态的直立次最大膝关节伸展运动中的证据，7名男性受试者以40次收缩/分钟的速度进行了7个不连续的增量运动阶段（3分钟/阶段），工作速率为60 - 75%的峰值有氧工作速率。通过连续多普勒超声对股动脉进行心肌周期平均血流量（MBF）反应和收缩平均血流量反应的计算。肌肉泵的净贡献是通过平均运动血流量（MBFM）和早期恢复血流量（MBFR）之间的差异来估计的。MBFM随功率输出的增加成比例增加，两种计算MBF的方法之间没有显著差异。在1期和5期，MBFM大于MBFR；对于所有其他的，MBFM与MBFR相似。对于较轻的工作速率（阶段1 - 4），运动和早期恢复平均动脉压（MAP）之间没有显着差异。在第5 - 7阶段，MAP在运动期间显著升高，在恢复早期显著下降。从这些结果我们得出结论：1)在最轻的工作速率下，肌肉泵对MBFM有净正效应；2)在稳态适度运动（阶段2 - 4）中，有节奏的肌肉收缩的净效应是中性的（即，肌肉收缩引起的阻抗正好被放松时的电位增强所抵消）；3)在三个更高的工作速率测试（阶段5 - 7）中，肌肉泵对MBFM有净正效应。松弛时血流的任何增强都不足以完全补偿收缩引起的肌肉灌注阻抗。这就需要更高的MAP来实现MBFM。
To test for evidence of a muscle pump effect during steady-state upright submaximal knee extension exercise, seven male subjects performed seven discontinuous, incremental exercise stages ( 3 min/stage) at 40 contractions/min, at work rates ranging to 60 - 75% peak aerobic work rate. Cardiac cycle-averaged muscle blood flow (MBF) responses and contraction-averaged blood flow responses were calculated from continuous Doppler sonography of the femoral artery. Net contribution of the muscle pump was estimated by the difference between mean exercise blood flow (MBFM) and early recovery blood flow (MBFR). MBFM rose in proportion with increases in power output with no significant difference between the two methods of calculating MBF. For stages 1 and 5, MBFM was greater than MBFR; for all others, MBFM was similar to MBFR. For the lighter work rates ( stages 1 - 4), there was no significant difference between exercise and early recovery mean arterial pressure ( MAP). During stages 5 - 7, MAP was significantly higher during exercise and fell significantly early in recovery. From these results we conclude that 1) at the lightest work rate, the muscle pump had a net positive effect on MBFM, 2) during steady-state moderate exercise ( stages 2 - 4) the net effect of rhythmic muscle contraction was neutral (i.e., the impedance due to muscle contraction was exactly offset by the potential enhancement during relaxation), and 3) at the three higher work rates tested ( stages 5 - 7), any enhancement to flow during relaxation was insufficient to fully compensate for the contraction-induced impedance to muscle perfusion. This necessitated a higher MAP to achieve the MBFM.