Pelvic elevation induces vertical kinetic energy without losing horizontal energy during running single-leg jump for distance

Abstract

In a running single-leg jump (RSLJ) for distance, the generation of vertical velocity without loss of horizontal velocity during the take-off phase is ideal, but difficult; however, we hypothesized that the pelvic rotation in the frontal plane achieved it. Here we show the effect of each segment rotation on the horizontal and vertical kinetic energies ($E_{horiz}$ and $E_{vert}$) of the centre of mass (CoM) during the take-off phase of an RSLJ for distance. We collected kinematic and ground-reaction-force data during RSLJs for distance by nine male long jumpers, involving an approximately 20-m approach in an outdoor field. We determined the components of the $E_{horiz}$ and $E_{vert}$ changes due to each segment movement. Elevation of the pelvic free-leg side increased $E_{vert}$ (0.53±0.16 J/kg, 9±3% of the total $E_{vert}$ change). Pelvic axial rotation decreased $E_{horiz}$, while pelvic elevation did not affect it (0.01±0.02 J/kg, no significant difference from zero). In contrast, forward rotations of the stance-leg shank and thigh decreased $E_{horiz}$ while simultaneously increasing $E_{vert}$. The results showed that pelvic elevation increased the vertical CoM velocity without causing a loss in horizontal velocity, although the lower-limb segments' effects on the vertical and horizontal velocities exhibited a trade-off, as previously speculated. RSLJs for distance have been frequently assumed as sagittal movements. However, our findings highlight the importance of three-dimensional pelvic movement, particularly in the frontal plane, for controlling both the vertical and horizontal velocities.Highlightsl We show the effect of each segment rotation on the horizontal and vertical kinetic energies ($E_{horiz}$ and $E_{vert}$) of the centre of mass during the take-off phase of a running single-leg jump for distance.l Elevation of the pelvic free-leg side increased $E_{vert}$ but did not decrease $E_{horiz}$, while the forward rotations of the stance-leg thigh and shank decreased $E_{horiz}$, while simultaneously increasing $E_{vert}$.l We highlight the importance of pelvic movement in the frontal plane for controlling both the vertical and horizontal velocities with single-leg stance.

Keywords: 3D analysis; biomechanics; kinetics; performance.