title: The effects of kinetic energy on concentric and eccentric isokinetic work.
abstract: This investigation examined inertial effects on work output during isokinetic concentric knee extension and eccentric knee flexion. Total work (Wtotal) included work due to kinetic energy (Wkin), with respect to gravity (Wgrav), and against the dynamometer (Wdyn). Eighteen resistance-trained participants (9 males, 9 females) performed maximal voluntary concentric (90, 150, 210, 270 deg/s) and eccentric (-150, -90, -30 deg/s) actions with the dominant leg. Differences between work measurement type (WMT), i.e., gravity-corrected work and Wtotal, were assessed. ANOVA (2 WMT x 2 mode x 2 gender x 4 speed) revealed significant main effects (p < 0. 05) for both factors concentrically but only for WMT eccentrically. It was concluded that the effect of kinetic energy during isokinetic leg extension may elicit differences in measurement where the associated error (Kerr) significantly increases with increasing velocity concentrically and decreases eccentrically. Key pointsTotal isokinetic work is underestimated by standard gravity corrected techniques.Standard gravity corrected work measurements overestimate isometric eccentric total work.The overestimation of isometric eccentric total work increases with greater angular velocity.
authors.affiliation: California Department of Corrections Southern Testing Center , Rancho Cucamonga, CA, USA.
authors.forename: Brian
authors.initials: B
authors.lastname: Boggess
authors.forename: Jeff
authors.initials: J
authors.lastname: Moffit
authors.forename: Jacobo
authors.initials: J
authors.lastname: Morales
authors.forename: Tim
authors.initials: T
authors.lastname: Anderson
keywords: Kinetic energy; kinetic error; work measurement type