Sado Natsuki, Yoshioka Shinsuke, Fukashiro Senshi
Faculty of Sport Sciences, Waseda University, Tokorozawa, Saitama, Japan; Department of Life Sciences, The University of Tokyo, Tokyo, Japan.
Department of Life Sciences, The University of Tokyo, Tokyo, Japan.
J Biomech. 2020 May 7;104:109751. doi: 10.1016/j.jbiomech.2020.109751. Epub 2020 Mar 16.
In single-leg jumps, humans achieve more than half the jumping height that they can reach for double-leg jumps. Although this bilateral deficit in jumping has been believed to be due to the reduction of leg extensor force/work exertions, we hypothesised that the three-dimensional biomechanical differences between double-leg and single-leg jumps also influence the bilateral deficit in jumping. Here, we show the substantial effect of the elevation of the pelvic free-leg side in single-leg squat jumps on the bilateral deficit in jumping in addition to extensor force reduction. We collected the kinematic and ground reaction force data during single-leg and double-leg squat jumps from ten male participants using motion capture systems and force platforms. We determined the components of the mechanical energy directly contributing to the height of the centre of mass due to segment movement. The energy due to rotations of the foot, shank, thigh, and pelvis were significantly greater in single-leg squat jumps than in double-leg squat jumps. The magnitudes of the difference in energy between single-leg and double-leg squat jumps due to the pelvis (0.54 ± 0.22 J/kg) was significantly larger than that due to any other segment (<0.30 J/kg). This indicates that pelvic elevation in single-leg jump is a critical factor causing bilateral deficit in jumping, and that humans generate the jumping height with a single leg not just by an explosive leg-extension but also by synchronous free-leg side elevation of the pelvis. The findings suggest that this pelvic mechanism is a factor characterising human single-leg jumps.
在单腿跳跃中，人类达到的跳跃高度超过了双腿跳跃时所能达到高度的一半。尽管人们一直认为跳跃中的这种双侧差异是由于腿部伸肌力量/做功的减少，但我们推测双腿跳跃和单腿跳跃之间的三维生物力学差异也会影响跳跃中的双侧差异。在此，我们展示了单腿深蹲跳中骨盆自由腿侧抬高对跳跃双侧差异的显著影响，此外还有伸肌力量的减少。我们使用运动捕捉系统和力平台收集了10名男性参与者单腿和双腿深蹲跳过程中的运动学和地面反作用力数据。我们确定了由于身体各节段运动而直接有助于质心高度的机械能组成部分。单腿深蹲跳中由于足部、小腿、大腿和骨盆旋转产生的能量显著高于双腿深蹲跳。单腿和双腿深蹲跳之间由于骨盆产生的能量差异幅度（0.54±0.22焦耳/千克）明显大于由于其他任何节段产生的差异幅度（<0.30焦耳/千克）。这表明单腿跳跃中骨盆抬高是导致跳跃双侧差异的关键因素，而且人类单腿跳跃达到的高度不仅是通过腿部的爆发性伸展，还通过骨盆自由腿侧的同步抬高。研究结果表明，这种骨盆机制是人类单腿跳跃的一个特征因素。
