Tokyo Metropolitan University, Tokyo, Japan.
Toin University of Yokohama, Kanagawa, Japan.
PLoS One. 2022 May 20;17(5):e0268634. doi: 10.1371/journal.pone.0268634. eCollection 2022.
This study investigated the mechanical role of metatarsophalangeal (MTP) joints in human jumping. Eighteen healthy young men performed three types of single-leg jumps (SJ: squat jump; CMJ: countermovement jump; HJ: standing horizontal jump) on a force plate under barefoot (BARE) and forefoot immobilisation (FFIM) conditions. For FFIM, the forefoot was immobilised around the MTP joints of the dominant leg by a custom-made splint. Force-time components and the centre of pressure (COP) trajectory were measured from the ground reaction force (GRF) in the take-off phase of jumping. The vertical jump heights calculated from the net vertical impulse were lower under FFIM than under BARE during the CMJ (p < 0.05). The HJ distance under FFIM was significantly shorter than that under BARE (p < 0.01). The relative net vertical impulse was lower under FFIM than under BARE during the CMJ (p < 0.05). During the HJ, all the horizontal GRF variables were significantly lower under FFIM than under BARE (p < 0.01), but none of the vertical GRF variables differed between the two conditions. The horizontal relative GRF in the 90-95% of the final take-off phase during the HJ was significantly lower under FFIM than under BARE (p < 0.01). Under FFIM, the COP range in the antero-posterior direction in the take-off phase of the HJ decreased (p < 0.05), whereas its range in the anterior direction for the SJ and CMJ increased (p < 0.05). The results of this study indicate that MTP joint motion can play an important role in regulating force-generating capacities of toe flexor muscles in the take-off phase of human jumping, especially in the horizontal direction of horizontal jumping.
本研究探讨了跖趾（MTP）关节在人类跳跃中的力学作用。18 名健康的年轻男性在赤脚（BARE）和前足固定（FFIM）条件下，在力板上进行了三种单腿跳跃（SJ：深蹲跳；CMJ：反向跳跃；HJ：站立水平跳跃）。对于 FFIM，通过定制的夹板将前足在优势腿的 MTP 关节周围固定。在起跳阶段，从地面反作用力（GRF）测量力-时成分和压力中心（COP）轨迹。从净垂直冲量计算的垂直跳跃高度在 FFIM 下比 BARE 下的 CMJ 低（p < 0.05）。FFIM 下的 HJ 距离明显短于 BARE 下（p < 0.01）。在 CMJ 期间，FFIM 下的相对净垂直冲量低于 BARE 下（p < 0.05）。在 HJ 期间，所有水平 GRF 变量在 FFIM 下均明显低于 BARE 下（p < 0.01），但两种条件下的垂直 GRF 变量均无差异。在 HJ 的最后起飞阶段的 90-95%期间，FFIM 下的水平相对 GRF 明显低于 BARE 下（p < 0.01）。在 FFIM 下，HJ 起跳阶段的 COP 范围在前后方向上减小（p < 0.05），而 SJ 和 CMJ 的前向范围增加（p < 0.05）。本研究的结果表明，MTP 关节运动在调节人跳跃起飞阶段脚趾屈肌的力产生能力方面可以发挥重要作用，尤其是在水平跳跃的水平方向。
