Evaluation of a dynamometer measuring torque of uni- and bilateral concentric and eccentric muscle action.

A dynamometer designed for torque measurements of uni- and bilateral concentric and eccentric muscle actions of the quadriceps and hamstring muscle groups is described. Torque reproducibility and control of lever-arm position were studied using known standards. In vivo measurements assessed angular velocity, lever-arm acceleration, variability of torque between limbs and reproducibility of torque. Torque obtained from left and right leg attachments was equal when using weights and during dynamic in vivo conditions. Static torque recorded at different lever-arm positions and known torque were equal. Likewise, lever-arm position output equated with known angles. In vivo test-retest of peak torque was found to be reliable. Acceleration of the lever arm was greater for concentric bilateral than for unilateral muscle actions but equal during eccentric muscle actions. The dynamometer is suggested to provide valid and reproducible torque measurements up to at least 700 N m at constant angular velocities up to 2.62 rad s-1. Besides being a research tool the dynamometer is useful in clinical settings for rehabilitation and evaluation of skeletal muscle function.