Libonati J R, Cox M, Incanno N, Melville S K, Musante F C, Glassberg H L, Guazzi M
Department of Cardiopulmonary Sciences, Exercise Physiology Laboratory, Northeastern University, Boston, MA 02115, USA.
Cardiologia. 1998 Dec;43(12):1355-60.
Prolonged periods of ischemia/reperfusion are known to deleteriously affect skeletal muscle performance. However, in animal models, brief bouts of both skeletal and cardiac muscle ischemia/reperfusion have been shown to decrease skeletal muscle injury and increase skeletal muscle force output, a phenomenon termed "preconditioning". Because there are transient periods of ischemia/reperfusion during isometric and concentric muscle contractions, the purpose of this study was to examine how short duration forearm occlusion/reperfusion prior to exercise, influenced isometric skeletal muscle force output in humans. Eleven subjects (6 men and 5 women, mean age 25 +/- 1 years) participated in this study. Using a Biodex multijoint ergometer, a protocol of isolated, isometric forearm wrist flexions was utilized to measure muscle force output in two separate trials. In the first trial, 15 isometric maximal voluntary contractions (MVCs) of the wrist flexors were performed in 20 intervals interspersed with 10 s of rest. In the second trial, forearm occlusion was induced (2 min at 200 mmHg by blood pressure cuff occlusion, with 10 s of hyperemia) prior to exercise. Following cuff occlusion, an identical exercise protocol was followed, i.e. 15 isometric wrist flexor MVCs performed in 20 intervals interspersed with 10 s of rest. The total force output over 15 MVCs was greater following intermittent cuff occlusion (no occlusion 2619 +/- 320 ft.lbs vs cuff occlusion 2986 +/- 195 ft.lbs; p < 0.05). The mean force output per MVC also increased during exercise following intermittent cuff occlusion (no occlusion 174 +/- 21 ft.lbs vs cuff occlusion 199 +/- 13 ft.lbs; p < 0.05). In a second set of experiments, we found a 3 to 4 fold hyperemic blood flow following cuff occlusion. These data suggest that brief periods of cuff occlusion/reperfusion may increase repetitive MVC force output by skeletal muscle. Although further study is needed to fully understand the effects of occlusion/reperfusion on skeletal muscle force output, we hypothesize that, in part, this putative effects is secondary to the hyperemic blood flow which follows cuff occlusion.
已知长时间的缺血/再灌注会对骨骼肌性能产生有害影响。然而，在动物模型中，短暂的骨骼肌和心肌缺血/再灌注已被证明可减少骨骼肌损伤并增加骨骼肌力量输出，这一现象被称为“预处理”。由于在等长和向心肌肉收缩过程中存在短暂的缺血/再灌注期，本研究的目的是探讨运动前短时间的前臂阻断/再灌注如何影响人类等长骨骼肌力量输出。11名受试者（6名男性和5名女性，平均年龄25±1岁）参与了本研究。使用Biodex多关节测力计，在两个单独的试验中采用孤立的等长前臂腕部屈曲方案来测量肌肉力量输出。在第一次试验中，腕屈肌进行15次等长最大自主收缩（MVC），分20个间隔进行，间隔期间穿插10秒休息。在第二次试验中，在运动前诱导前臂阻断（通过血压袖带阻断在200 mmHg下持续2分钟，伴有10秒充血）。袖带阻断后，遵循相同的运动方案，即进行15次等长腕屈肌MVC，分20个间隔进行，间隔期间穿插10秒休息。间歇性袖带阻断后15次MVC的总力量输出更大（无阻断时为2619±320英尺磅，袖带阻断时为2986±195英尺磅；p<0.05）。间歇性袖带阻断后运动期间每次MVC的平均力量输出也增加（无阻断时为174±21英尺磅，袖带阻断时为199±13英尺磅；p<0.05）。在第二组实验中，我们发现袖带阻断后充血血流量增加了3至4倍。这些数据表明，短暂的袖带阻断/再灌注可能会增加骨骼肌重复性MVC力量输出。尽管需要进一步研究以充分了解阻断/再灌注对骨骼肌力量输出的影响，但我们推测，部分这种假定的影响继发于袖带阻断后的充血血流量。
