Comparison of dynamic strength as measured by the cybex and mini-gym isokinetic dynamometers

The dynamic nature of manual material handlings tasks may preclude the use of traditional static strength measurements. Isokinetic dynamometers, such as the Cybex and Mini-Gym, offer alternative measurements. Unfortunately the Cybex, though accurate, is very expensive and cumbersome, while the Mini-Gym though portable and cheap may lack preciseness. Elbow flexion, shoulder flexion, shoulder abduction, trunk extension, hip flexion and extension, and knee flexion strengths were measured on five males and four females on both the Cybex and the Mini-Gym. Joint torques and joint positions were measured continuously over time over a variety of different angular velocities. Typical torques over range of motion data indicated an inverted-U shaped curve with torques doubling from a low value at one extreme angle to the high point at mid range of motion then decreasing thereafter. Peak torques decreased with increasing angular velocities. There were large significant differences in the isokinetic data as collected on both devices. Only certain types of movements could be measured on the Mini-Gym. Peak forces were typically lower on the Mini-Gym. The lack of a fixed moment arm on the Mini-Gym allowed other muscle groups to contaminate specific joint movements and degraded the desired angular motion. Accepting these limitations, the Mini-Gym can still be used as an industrial strength testing device. It is inexpensive, simple, portable and can measure the strength of gross muscle action adequately.