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

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 (Evert) in RSLJ. We determined the component of increase in Evert 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 Evert (0.76 ± 0.70 J/kg). Evert 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 (Ehori) to Evert.Evert 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 Evert 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 Ehori to Evert by shank and thigh rotations, and a wide and short pelvis for increasing Evert by pelvic elevation. This study provides quantifiable evidence to indicate how substantially non-extension movements contribute to higher RSLJ.