Differences in elbow flexion torque measured concentrically, eccentrically, and isometrically

The purposes of this study were to describe torque-velocity relationships during concentric, eccentric, and isometric testing of elbow flexor muscles and to determine test-retest reliability of a specific isokinetic testing protocol. Thirty healthy women were tested using an isokinetic dynamometer at velocities of 0 degrees, 30 degrees, 120 degrees, and 210 degrees/sec. Reliability was assessed in 20 of the subjects by retesting concentric and eccentric torques at 30 degrees and 120 degrees/sec after a 30-minute rest interval. The highest torque from three maximal efforts was considered to be peak torque. Mean eccentric peak torque was greater than either isometric or concentric peak torque; as isokinetic test velocity increased, the differences between concentric and eccentric torques became larger. Intraclass correlation coefficients ranged from .72 to .83, indicating lack of consistency between test and retest torques. Consecutive concentric-eccentric testing and lack of mechanical stabilization might have contributed to test-retest variability and to the relatively small differences between concentric and eccentric torques. Continued study of reliability of isokinetic testing protocols and further investigation of concentric-eccentric torque-velocity relationships are advocated.