Kramer J F, Vaz M D, Hakansson D
Department of Physical Therapy, Faculty of Applied Health Sciences, University of Western Ontario, London, Canada.
Med Sci Sports Exerc. 1991 Feb;23(2):231-7.
The purpose of this study was to determine whether the magnitude of the activation force, defined as the force that must be applied to the load cell in order to activate the resistance arm of an isokinetic dynamometer, affected knee extensor torques. Twenty-four healthy female subjects performed resisted knee extension through the range of 95 degrees to 5 degrees knee flexion, with a 5-s rest between concentric and eccentric muscle actions. Six exercise sets, composed of the combinations of activation force (20,50, and 100 N) and angular velocity (45 and 135 degrees.s-1), were randomly assigned on each of two occasions, completed within a 10-d period. Although peak torques were not affected by the activation force, average torques, eccentric torques at mid-range (50 degrees knee flexion), and torques during the initial portion of each muscle action (80 degrees knee flexion during concentric muscle actions and 20 degrees flexion during eccentric actions) increased as the activation force increased. The effect of the activation force tended to be more pronounced during eccentric than during concentric muscle actions, and at the faster angular velocity. Comparisons of torques should be based on similar test protocols, including activation force.
本研究的目的是确定激活力（定义为为激活等速测力计的阻力臂而必须施加于测力传感器的力）的大小是否会影响膝关节伸肌扭矩。24名健康女性受试者在膝关节从95度屈曲到5度的范围内进行抗阻膝关节伸展，在向心和离心肌肉动作之间休息5秒。在10天内分两次随机分配由激活力（20、50和100牛）和角速度（45和135度·秒⁻¹）组合而成的六组运动。尽管峰值扭矩不受激活力影响，但平均扭矩、膝关节屈曲50度时的离心扭矩以及每个肌肉动作初始阶段（向心肌肉动作时膝关节屈曲80度，离心动作时膝关节屈曲20度）的扭矩随着激活力的增加而增加。激活力的影响在离心肌肉动作中往往比在向心肌肉动作中更明显，且在角速度更快时更明显。扭矩比较应基于相似的测试方案，包括激活力。
