Validity of lower extremity strength and power utilizing a new closed chain dynamometer

Purpose: The purpose of this study was to compare selected variables measur ed on a traditional isokinetic dynamometer (Cybex II) with a new lower extr emity, closed chain dynamometer (Omnikinetic, OmK). Methods: Twelve subject s (6 male, 6 female, age = 28 +/- 5 yr, mean +/- SD) performed Cybex II kne e flexion and extension at 1.05, 3.14, and 5.23 rad.s(-1). A maximal effort of 10 repetitions of lower extremity concentric extension and eccentric fl exion at 36% of subject's 1-RM was performed on the OmK. Crank power and jo int (ankle, knee, and hip) kinetics were recorded as a mean of 10 repetitio ns. Results: t-Tests revealed right versus left leg differences (P < 0.05) for Cybex II peak torque flexion at 5.23 rad.s(-1), and OmK knee and hip pe ak power and hip root mean square power (RMS) power. Cybex peak knee torque s were related (Pearson r values 0.78-0.92, P < 0.01) to OmK peak knee torq ues. Cybex average power was related to OmK knee power (Pearson r values 0. 71-0.96, P < 0.01) and OmK crank power (r = 0.62-0.94, P <.01). Correlation s tended to be stronger comparing the OmK with the fastest (5.23 rad.s(-1)) Cybex II speed. Conclusions: These results suggest that the OmK knee and c rank kinetic data are comparable to Cybex II isokinetic dynamometry. The ab ility to evaluate lower extremity joint exercise at a subject's maximal mov ement speed, in addition to the use of a closed-chain, multi-joint motion, may allow for the OmK to provide a more global evaluation of lower extremit y kinetics during seated concentric-extension, eccentric-flexion exercise.