Faculty of Health and Sport Sciences, University of Tsukuba, Ibaraki 305-8574, Japan
Japan Institute of Sports Sciences, Tokyo 115-0056, Japan.
Biol Open. 2014 Jul 4;3(8):689-99. doi: 10.1242/bio.20148284.
This study investigated kinematics of human accelerated sprinting through 50 m and examined whether there is transition and changes in acceleration strategies during the entire acceleration phase. Twelve male sprinters performed a 60-m sprint, during which step-to-step kinematics were captured using 60 infrared cameras. To detect the transition during the acceleration phase, the mean height of the whole-body centre of gravity (CG) during the support phase was adopted as a measure. Detection methods found two transitions during the entire acceleration phase of maximal sprinting, and the acceleration phase could thus be divided into initial, middle, and final sections. Discriminable kinematic changes were found when the sprinters crossed the detected first transition-the foot contacting the ground in front of the CG, the knee-joint starting to flex during the support phase, terminating an increase in step frequency-and second transition-the termination of changes in body postures and the start of a slight decrease in the intensity of hip-joint movements, thus validating the employed methods. In each acceleration section, different contributions of lower-extremity segments to increase in the CG forward velocity-thigh and shank for the initial section, thigh, shank, and foot for the middle section, shank and foot for the final section-were verified, establishing different acceleration strategies during the entire acceleration phase. In conclusion, there are presumably two transitions during human maximal accelerated sprinting that divide the entire acceleration phase into three sections, and different acceleration strategies represented by the contributions of the segments for running speed are employed.
本研究通过 50 米短跑探讨了人类加速冲刺的运动学，并检验了在整个加速阶段是否存在加速度策略的转变和变化。12 名男性短跑运动员进行了 60 米短跑，在此过程中，使用 60 个红外摄像机逐步捕捉运动学。为了检测加速阶段的转变，采用整个支撑阶段整个身体重心（CG）的平均高度作为衡量标准。检测方法在最大冲刺的整个加速阶段发现了两个转变，因此可以将加速阶段分为初始、中间和最后三个部分。当短跑运动员穿过第一个被检测到的转变时（CG 前方的脚触地，支撑阶段膝关节开始弯曲），以及穿过第二个被检测到的转变时（身体姿势的变化结束，髋关节运动强度开始轻微下降），会发现可区分的运动学变化，从而验证了所采用的方法。在每个加速部分，下肢各节段对 CG 前向速度增加的贡献不同——初始部分为大腿和小腿，中间部分为大腿、小腿和脚，最后部分为小腿和脚——这建立了整个加速阶段不同的加速度策略。总之，人类最大加速度冲刺可能存在两个转变，将整个加速阶段分为三个部分，并采用代表跑步速度的各节段贡献的不同加速度策略。
