Reliability of a reciprocal test protocol performed on the kinetic communicator: an isokinetic test of knee extensor and flexor strength.

This study tested knee extensor and flexor strength using a reciprocal testing protocol on the Kin-Com isokinetic dynamometer. The purposes were: 1) to identify the variability associated with subjects, repetitions, occasions, and their various interactions; 2) to express the overall measurement error in clinically relevant terms; and 3) advance a strategy for maximizing reliability while simultaneously ensuring that all major sources of measurement error are represented. Fourteen healthy women were tested on two separate occasions (test sessions). On each occasion, measurements of knee extensor and flexor peak torque, average torque, and peak torque angle were gathered for each subject. The results indicated a high overall reliability (range 0.936-0.952) for all measures except peak torque angle (0.630-0.799). Reliability coefficients were consistently lower between occasions than among repetitions, indicating that this type of testing should occur on more than one occasion so as to include all sources of measurement error. This study has expressed measurement error in clinically relevant terms using a 95% confidence range. The findings indicate that a high reliability for isokinetic leg strength measurements can be achieved using a reciprocal testing protocol on the Kin-Com device.J Orthop Sports Phys Ther 1988;10(6):218-223.