Association of muscle coactivation during isometric and isokinetic knee extension with muscle strength and physical performance

Abstract

Purpose: The purpose of this study was to examine the association of muscle coactivation during isometric and isokinetic knee extension with muscle strength and physical performance. Subjects: Nineteen healthy young adults were recruited for this study. Methods: Electromyograms of the biceps femoris and vastus lateralis were recorded and the coactivation index (CAI) of isometric and isokinetic knee extension was calculated. We also measured muscle strength during knee extension and the timed up and go test time. Results: A significant relationship was revealed between CAI and muscle strength in isokinetic knee extension. The timed up and go test time was associated with CAI in both isometric and isokinetic knee extension. Conclusion: These findings suggest that higher coactivation is associated with lower muscle strength and slower timed up and go test time.