Hunter Sandra K, Griffith Erin E, Schlachter Kristine M, Kufahl Tim D
Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin 53233, USA.
Muscle Nerve. 2009 Jan;39(1):42-53. doi: 10.1002/mus.21203.
The purpose of this study was to compare the time to task failure, postcontraction hyperemia, and vascular conductance of young men and women for a submaximal intermittent fatiguing contraction performed with the handgrip muscles. Twenty men and 20 women (mean +/- SD: 22 +/- 4 years) performed an isometric contraction at 50% of maximal voluntary contraction (MVC) (6-s contraction, 4-s rest) until task failure. Forearm venous occlusion plethysmography was used to estimate the peak blood flow (after 10-min occlusion) and blood flow at rest after 6-s submaximal contractions of varying intensities, and during an intermittent fatiguing contraction at 1-min intervals and task failure. The time to task failure was longer for the women compared with the men (408 +/- 205 s vs. 297 +/- 57 s, P < 0.05). Postcontraction hyperemia and vascular conductance were greater for men than for women after nonfatiguing 6-s submaximal contractions performed at 20%, 40%, 50%, 60%, and 80% of MVC force (P < 0.05). In contrast, hyperemia and vascular conductance were similar for both genders when measured at 50 s into the fatiguing contraction, at each minute thereafter, and at task failure. Regression analysis indicated that the rate of electromyographic activity and perceived exertion were the significant predictors of the time to task failure. The longer time to task failure for women compared with men for an intermittent fatiguing contraction with handgrip muscles was not explained by postcontraction hyperemia or vascular conductance with fatigue.
本研究的目的是比较年轻男性和女性在进行次最大强度间歇性疲劳收缩时，手部肌肉任务失败的时间、收缩后充血情况以及血管传导性。20名男性和20名女性（平均±标准差：22±4岁）以最大自主收缩（MVC）的50%进行等长收缩（6秒收缩，4秒休息），直至任务失败。使用前臂静脉闭塞体积描记法估计在不同强度的6秒次最大收缩后10分钟闭塞时的峰值血流量以及休息时的血流量，以及在1分钟间隔的间歇性疲劳收缩期间和任务失败时的血流量。与男性相比，女性任务失败的时间更长（408±205秒对297±57秒，P<0.05）。在以MVC力的20%、40%、50%、60%和80%进行非疲劳性6秒次最大收缩后，男性的收缩后充血和血管传导性大于女性（P<0.05）。相比之下，在疲劳收缩50秒时、此后每分钟以及任务失败时测量，两性的充血和血管传导性相似。回归分析表明，肌电图活动率和主观用力感觉是任务失败时间的重要预测因素。女性在手部肌肉间歇性疲劳收缩中任务失败时间比男性长，这不能用收缩后充血或疲劳时的血管传导性来解释。
