Preload release increases blood flow and decreases fatigue during repetitive isotonic muscle contractions.
Preload release increases blood flow and decreases fatigue during repetitive isotonic muscle contractions.
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预载释放可增加血流量并减少重复等张肌肉收缩期间的疲劳。
DOI：
10.1152/jappl.1994.77.6.2641
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发表时间：
1994
期刊：
影响因子：
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通讯作者：
Stainsby,WN
中科院分区：
文献类型：
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作者：
Ameredes,BT;Brechue,WF;Stainsby,WN
在犬腓肠肌-跖肌原位上研究了预负荷对血流量（Q）、摄氧量（VO 2）和疲劳的影响。在高前负荷（HP; 69 g/g，n = 5）、低前负荷（LP; 35 g/g，n = 6）和前负荷释放（PR; 0 g/g，n = 5）实验中进行重复（1次收缩/s，持续时间200 ms）后负荷（0.25-0.3最大主动等长张力）等张强直收缩。最大Q值（1.0、1.6和2.1 ml.min-1.g-1，所有比较P < 0.05）和Q2输送（8、13和17 mumol.min-1.g-1，所有比较P < 0.05）随前负荷降低而显著增加。HP的最大VO 2为7.2 mumol.min-1.g-1，显著低于LP（10.5 mumol.min-1.g-1，P < 0.05）和PR值（11.4 mumol.min-1.g-1，P < 0.05），这些差异持续到20 min的收缩。在HP、LP和PR收缩20分钟时，疲劳（测量为功率产生的损失）分别为63%、37%和23%，表明随着前负荷的降低，疲劳显著降低（所有比较P < 0.05）。这些数据表明，前负荷，目前作为被动张力保持收缩之间的水平，可以影响Q，VO 2，和疲劳在重复等张强直性收缩的肌肉原位通过机械确定的代谢调制的动态肌肉性能。
The effects of preload on blood flow (Q), O2 uptake (VO2), and fatigue were investigated in the canine gastrocnemius-plantaris muscle in situ. Repetitive (1 contraction/s, 200 ms duration) afterloaded (0.25–0.3 maximal active isometric tension) isotonic tetanic contractions were performed in high-preload (HP; 69 g/g, n = 5), low-preload (LP; 35 g/g, n = 6), and preload-release (PR; 0 g/g, n = 5) experiments. Maximal Q values (1.0, 1.6, and 2.1 ml.min-1.g-1, P < 0.05 for all comparisons) and Q2 delivery (8, 13, and 17 mumol.min-1.g-1, P < 0.05 for all comparisons) increased significantly with decreasing preload. The maximal VO2 of HP was 7.2 mumol.min-1.g-1, which is significantly lower than both LP (10.5 mumol.min-1.g-1, P < 0.05) and PR values (11.4 mumol.min-1.g-1, P < 0.05); these differences were sustained through 20 min of contractions. Fatigue, measured as a loss of power production, was 63, 37, and 23% at 20 min of contractions in HP, LP, and PR, respectively, indicating significantly less fatigue with decreasing preload (P < 0.05 for all comparisons). These data demonstrate that the preload, present as the level of passive tension maintained between contractions, can influence Q, VO2, and fatigue during repetitive isotonic tetanic contractions of muscle in situ by a mechanically determined metabolic modulation of dynamic muscle performance.