Relationship Between Closed-Linear-Kinetic- and Open-Kinetic-Chain Isokinetic Strength and Lower Extremity Functional Performance

Context: Isokinetic strength and functional performance are used to assess recovery after rehabilitation. It is not known whether low-speed closed-linear-kinetic isokinetic muscle strength correlates with functional performance. Objective: To investigate the relationship between linear closed (CKC) and open (OKC) concentric isokinetic strength of the dominant lower-limb extensors and functional performance. Design: Correlational analysis. Setting: University laboratory. Participants: Thirty uninjured men and women (age = 20.9 ± 2.4 years). Main Outcome Measures: Peak CKC and OKC isokinetic strength and best score from a shuttle run for time, single-leg vertical jump, and single-leg hop for distance. Results: Neither lower-limb CKC nor OKC isokinetic strength measured at low speeds correlated highly with performance on the functional tasks of jumping, hopping, and speed/agility. Conclusions: Although the basis of both closed and open isokinetic strength must be appreciated, they should not be the only determinants of functional performance.