Comparison of two methods for measuring hamstring reaction time using the Kin-Com isokinetic dynamometer.

Methods for quantifying deficits in proprioceptive feedback need to be examined. The purpose of this study was to compare two protocols measuring hamstring reaction time. Forty subjects, 13 males and 27 females, between 21 and 31 years of age (means = 24.3, SD = 2.04) were tested bilaterally on the Kin-Com isokinetic dynamometer with simultaneous use of the KC-EMG electromyograph. Subjects were instructed to maximally contract their hamstring musculature in response to a sudden lever arm movement. The peak torque time (PTT) protocol quantified the time lapse between initial lever arm movement and the generation of maximum torque. The electromyograph time (EMGT) protocol measured the time lapse between initial lever arm movement and initial myoelectrical activity of the hamstring musculature. Both PTT and EMGT were found to be reliable (Cronbach alpha 0.823-0.896), with no significant difference (p < .05) between dominant and nondominant limbs. These results indicate that PTT and EMGT are effective for quantifying hamstring reaction time and that the uninvolved lower extremity may be used as a control.