Non-extension movements inducing over half the mechanical energy directly contributing to jumping height in human running single-leg jump

Abstract

The running single-leg jump (RSLJ), including certain non-extension movements (movements not induced by lower-limb extension works), is the highest jumping mode in humans. Here, we show the substantial contributions of non-extension movements, in generating mechanical energy directly contributing to the jumping height (E_vert) in RSLJ. We determined the component of increase in E_vert due to each segment movement in RSLJs by 13 male high-jumpers. The stance-leg shank forward rotation (rotation opposite to the actions of the knee extensors and ankle plantar flexors on the shank), increased E_vert (0.76 ± 0.70 J/kg). E_vert due to the stance-leg thigh forward rotation (4.39 ± 0.57 J/kg) was substantially larger than the inflowing energy into the thigh (difference: 2.36 ± 0.42 J/kg). These results suggest that the forward rotations of the shank and thigh transformed horizontal kinetic energy (E_hori) to E_vert.E_vert was increased by the elevation of the free-leg side of the pelvis (0.53 ± 0.22 J/kg) and rotation of free-leg thigh (1.52 ± 0.26 J/kg). The non-extension movements contributed to over half (59 ± 6%) the increase in E_vert during the take-off phase. Human-specific morphologies are essential for the contributions of non-extension movements; fully extensible knee joints and relatively longer legs with respect to body mass for the transformation from E_hori to E_vert by shank and thigh rotations, and a wide and short pelvis for increasing E_vert by pelvic elevation. This study provides quantifiable evidence to indicate how substantially non-extension movements contribute to higher RSLJ.

Keywords: External work; Human-specific; Pivoting movement; Three-dimension.