Abstract
ABSTRACT Purpose We aimed to clarify how the horizontal force-velocity (Fv h) relationship during over-ground sprint running differs with horizontal resistance loads and profiling methods (multiple- and single-trial methods). Methods Twelve males performed sprint running (one unresisted and five resisted) using a motorized loading device. During the trials, the ground reaction forces at every step were obtained using a 50 m force plate system. The step-averaged Fv h relationships were then determined using single- and multiple-trial methods with linear and curvilinear models. The differences in Fv h parameters between loading conditions and between profiling methods, as well as the goodness of fit of the regression models to the measured data, were examined. Results We found that Fv h plots in each loading condition almost overlapped during acceleration, whereas, the horizontal forces deviated toward a lower value around maximal velocity; the linear Fv h parameters derived using the single-trial method had a load-dependency; the linear Fv h relationship derived from the multiple-trial method had a bias toward lower force values with less negative slopes compared with the single-trial method; the curvilinear models fitted the pooled data of all loading conditions better than the linear model; and the Fv h relationship within the velocity range of unresisted sprinting was almost linear. Conclusions The results of this study indicate that the reported load-dependency of Fv h parameters is mainly due to large horizontal forces at very low velocities in resisted sprinting, and the profiling method-dependency is mainly due to the attenuation of horizontal force around the maximal velocity of each loading condition. Factors of deviations from a linear Fv h relationship in horizontal force and the validity and usefulness of nonlinear models require further investigation.
Published Version
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