Isokinetic, isometric and isotonic strength relationships

Relationships among isokinetic, isometric and isotonic strength measurements in knee and elbow extension and flexion were examined in 16 young, healthy men. Isokinetic and isometric torque measurements were obtained from modified Cybex II apparatus. Isokinetic torque values were obtained at velocities of 36 degrees/sec, 108 degrees/sec, and 180 degrees/sec. An electrogoniometer was used to monitor joint angle. A device similar to a Noland-Kuckhoff (NK) table was employed to determine maximal isotonic capabilities using a 1 repetition maximum procedure. Correlations among the 3 testing modes at joint angles of peak isometric torque were generally high (mean = 0.78, range = 0.97 to 0.47) for all 4 muscle groups. The amounts of common variance suggested that all 3 strength testing modes were measuring a similar phenomenon which could be termed maximal voluntary strength. Within a particular muscle group correlations decreased as isokinetic velocities and joint angles became more widely separated.