1Department of Track and Field 2Department of Biomechanics, University School of Physical Education in Wroclaw, Wroclaw, Poland 3Faculty of Sport, University of Ljubljana, Ljubljana, Slovenia.
J Strength Cond Res. 2013 Oct;27(10):2674-84. doi: 10.1519/JSC.0b013e31825fce65.
The purpose of this study was (a) to investigate the effect of the different foot movement (placement) during take-off and the initial knee joint angle used in standing long jump by the ground reaction forces analysis and 3-dimensional motion analysis (BTS SMART motion) and (b) investigate how the jump performances of different foot placement is related to the electromyography (EMG) activity (Noraxon) of 3 selected muscle groups (m. gastrocnemius, m. gluteus maximus, m. rectus femoris, m. tibialis anterior, m. biceps femoris, and m. vastus medialis). Six high caliber sprinters (100 m: 10.87 ± 0.38 seconds and 400 m: 46.75 ± 1.05 seconds) performed a series of jumps from parallel and straddle foot placement at take-off on a 2 force platform (Kistler model 9286B) to determine if a different pattern of take-off improves jumping distance. Using kinematic and kinetic data, the knee joint angle, the trajectories of center of mass (COM), magnitude of take-off peak force, and impulse during take-off phase were calculated. Average standing long jump performances with straddle foot placement were 13.58 cm (5.18%) above that from parallel feet placement. The take-off velocity with 90° knee initial angle initiation of take-off was not different (1.18 and 1.17 m·s, respectively) between the 2 jumps. The take-off angles on the COM trajectory also showed differences (69.87 and 66.8°, respectively) between each other. The contribution (EMG activation) made by the 6 muscles were almost the same during all phases for the 2 jumps; however, some differences can be found, in either unilateral (single leg) or sums of both legs (bilateral) measurements. A recommendation can be formulated that the contribution of straddle foot placement during take-off can significantly increase the value of power measurement especially when the evaluation requires a complex movement structure with the division on the left and right legs, for example, sprint start from block.
（a）通过地面反作用力分析和 3 维运动分析（BTS SMART 运动）研究起跳时不同脚部运动（放置）和初始膝关节角度对跳远成绩的影响；（b）研究不同脚部放置的跳远成绩如何与肌电图（Noraxon）活动（3 个选定肌肉群（m. gastrocnemius、m. gluteus maximus、m. rectus femoris、m. tibialis anterior、m. biceps femoris 和 m. vastus medialis）相关。6 名高水平短跑运动员（100m：10.87±0.38 秒和 400m：46.75±1.05 秒）在 2 个力平台（Kistler 模型 9286B）上从平行和分腿脚放置进行一系列跳跃，以确定不同的起飞模式是否能提高跳跃距离。使用运动学和动力学数据，计算膝关节角度、质心（COM）轨迹、起飞峰值力大小和起飞阶段的冲量。分腿脚放置的平均跳远成绩比平行脚放置高出 13.58cm（5.18%）。以 90°初始膝关节角度开始起飞的起飞速度在 2 次跳跃中没有差异（分别为 1.18 和 1.17m·s）。COM 轨迹上的起飞角度也存在差异（分别为 69.87 和 66.8°）。在 2 次跳跃中，6 块肌肉在所有阶段的贡献（肌电图激活）几乎相同；然而，在单侧（单腿）或双侧（双侧）测量中，都可以发现一些差异。可以提出这样的建议，即起飞时分腿脚放置的贡献可以显著增加功率测量的值，特别是在评估需要左腿和右腿分开的复杂运动结构时，例如从起跑器开始的短跑。
