竞技体育,科技先行——上海体育学院运动技能研究中心撑杆跳高“运动科技助力”项目


撑杆跳高运动在田径项目的分门别类中始终占有着非常特殊的地位——单次运动进程虽然耗时极短,却包含着举杆冲刺、插杆入斗、持杆起跳、杆上动作等多个身体维度的不同组合,这使得这项运动的技术性非常复杂。从运动员的角度来说,“复杂”意味着除了静态身体素质的要求严苛以外,更需要他们和教练团队清楚地了解到整个过程中的各种细节。自2018年以来,上海体育学院运动技能研究中心利用先进技术成功完成了多次专门针对国内外高水平撑杆跳高运动员技术动作过程中动作数据的采集分析和报告。奇石乐生物力学测力台因其准确的动态测量技术和易于安装、方便集成的特点,有效帮助研究团队实现赛道上瞬时力值复杂变化的采集任务。

上海体育学院创建于1952年,至今已有近70年历史。作为中国最早的体育高等学府之一,其运动技能研究中心(下称SPRC)是2003年在国家财政部与上海市政府的中央与地方共建项目资助下成立的,国内一流实验测试大厅和科研设备场所。SPRC成立十多年以来,不同方向上的各类科研项目涉及三个大类:

1.竞技体育项目的生物力学——帮助高水平乃至国家级运动员和教练团队提高比赛水平、优化运动能力、改善技术动作;

2.中心传统优势科研项目的运动装备(鞋、服装、护具、用品)生物力学研究——与国际一流运动装备厂商合作,开发专业装备、预防运动损伤、提高比赛表现;

3.最新前沿技术的探索——神经生物力学增能等。此次撑杆跳高项目,既是学院响应国家倡议下田径比赛周期内的备战工作,也是研究中心自短跑、游泳及球类运动之后,转型针对国内运动科研领域“冷门”项目的一次挑战。

“像这样的大范围的三维动作,过去在生物力学研究当中,如果能够全部把它捕捉下来,实际上还是有一定难度的。”刘宇教授(上海体育学院科学研究院院长,教育部“长江学者”特聘教授、美国国家体育科学院the National Academy of Kinesiology NAK外籍院士)是本次项目团队的带头人。“那么也就是借助这个平台,我们可以收集撑杆跳高运动员动作过程中身体各个部位的运动、身体重心的运动、各个关节的角度变化、助跑的步长、步频、步速以及地面反作用力——一个是起跳前最后三步每一步的三维地面反作用力,一个是插杆起跳过程里穴斗对杆子的三维反作用力。这些信息如果光靠教练员的肉眼是很难得到的。”

刘宇教授身为国际一流的运动生物力学专家,对于整个项目给予了很高的评价:

实验帮助我们从运动学和动力学的角度捕捉运动员在整个撑杆跳高过程中的所有数据,为教练员提供技术分析结果、训练计划的建议,还将建立撑杆跳高运动员动作技术以及能量模型。'
上海体育学院科学研究院院长刘宇教授

 

在种类繁多的研究过程中,数字推断和物理模型建立的基础是一直不变的——需要对测试对象进行实时的动作捕捉和力值监测。自2004年研究中心大范围扩建以来,对于尖端运动学和生物力学技术的引入始终保持着开放积极的态度。2018年年末,研究中心就将奇石乐测力台视为可以在测试中助力准确观测运动员瞬时表现的理想设备引入至学院田径场地,铺设在外侧跑道路面下方的轨道内,并基于撑杆跳项目的需要提前规划好了安装穴位和通道。因此,学校师生可以在很短的时间内对测力台进行位置的移动和测试前的设置。其灵活性极大地帮助缩减测试搭建的时间和人力成本。在这一次撑杆跳项目的准备阶段,三组测力台在奇石乐专业工程师的帮助下仅仅用时半个小时就能顺利完成了在测试专用跑道的安装工作。

同时,为了准确地获得撑杆跳选手后三步蹬地位置的中心数据,在每一个运动员开测前都必须按照其各自独有的起跳步伐节奏来微调测力台的相对位置。测力台设置的便利性确保了测试当天的三名运动员可以几乎做到无缝衔接地逐一上场完成测试,提高了测试效率。

另一方面,奇石乐生物力学应用部门为这项运动特地研发了Z20903型三维智能化撑杆跳穴斗测力台。该测力台采用坚固的结构设计,从几何形态和运动功能上来说都与普通的标准撑杆跳插斗完全匹配,奇石乐引以为傲的压电测量技术能够自杆头接触穴斗的瞬间开始记录整个力值变化的详细曲线——从插杆、起跳导致的瞬间力值陡升,到悬垂、摆体过程中随着竿子形变到达峰值,随后跟随运动员举腿、引体慢慢回落。在以毫秒为单位的极短瞬间内,杆头的力值会进行方向和数值上的突然变化,需要测力台兼具宽泛的测量范围、较高的固有频率和出色的动态脉冲响应水平。

撑杆跳测试项目装备

  • Qualisys 700+ 摄像机 22 台

  • Qualisys 210c 摄像机 1 台

  • Kistler 测力台 3 块

  • Kistler 撑杆跳测力穴斗 1 个

  • Optojump  20米

Pole Vault facility at the Shanghai University of Sport, equipped with force plates from Kistler
View of the pole vault facility at the Research Center of the Shanghai University of Sport, equipped with force plates from Kistler and optical measurement solutions.

Basic research and development of elite athletes

SUS was founded nearly 70 years ago, making it one of China’s longest-established higher educational institutions specializing in sports. The SPRC was added to the university in 2003: its superb hall, including a range of biomechanical equipment, was built with the help of government and municipal funding. The center covers three main research areas. First, biomechanics in competitive sport, with the focus on top athletes and national team members (as well as their trainers, of course): the goal here is to improve performance and athletic abilities in general. The second key area involves collaboration with manufacturers of sports apparel such as footwear, shirts and protective equipment, so that biomechanical information can be exploited to prevent injuries and develop athletes' performance. And the SPRC's third area of interest is research into innovations in various fields: neuropriming is one example. 

The SPRC's pole vault project fulfills a dual purpose: on the one hand, China's best athletes are prepared for the next track and field season in the run-up to the Olympic Games, as part of the "Technology-empowered Olympics" initiative launched by the General Administration of Sport of China. The second objective is to study a sport that is chronically under-researched in China, following on from the success of similar programs for sprint, swimming, and ball sports.

Precisely capturing force actions in the movement sequence

"In earlier biomechanical research, it was actually quite difficult to capture such a wide range of 3D motions in their entirety,” according to Professor Liu Yu, Dean of the Research Institute at SUS, a national award-winner and Fellow of the U.S. National Academy of Kinesiology, who heads the project. He continues:

“Thanks to the system from Kistler, we can capture the movements of the body's center of gravity and also of individual parts of the body, as well as the resultant angles and the length, frequency, and speed of the run-up. What's more, the forces in all three spatial dimensions are measured – including, in particular, the force exerted by the athlete on the ground in his or her last three steps, and when the pole is planted in the box. This kind of information is not available to coaches who only observe athletes with the naked eye.”

Professor Liu Yu, Dean of the Research Institute at Shanghai University of Sport

In research of this sort, data and model quality is critically dependent on precise acquisition of movements and force measurement in real time. Knowing this, the SPRC decided to opt for leading kinematics and biomechanics technology right from the start of the project. Towards the end of 2018, initial tests with three 9287C force plates from Kistler were carried out in the open-air facility; plans were then drawn up for further integration, including the installation work needed for the pole vaulting project. This already allowed trainers and students to try out the equipment and get to know it, greatly reducing the amount of work and time needed to set up the tests.

With assistance from Kistler, it took only half an hour to install the three sets of force plates in the dedicated measurement track for the project in the hall. But to ensure that the data on each pole vaulter's last three steps was as accurate as possible, the force plates had to be aligned in exactly the right positions prior to every test. This was easily achieved thanks to the simple installation procedure for the equipment, so full data acquisition for three athletes was completed in just one day.

Custom measurement solution for the planting box

In addition, the Kistler engineers developed a multi-component force measuring box specifically intended for pole vaulting applications. The box features an exceptionally robust design, and it precisely replicates the function and geometry of the actual planting box. The integrated piezoelectric sensors supply an accurate force curve – from the moment when the pole touches the planting box, as the force increases continuously, until the tension built up in the pole due to deformation is released and the force then decreases as the athlete gradually lets go of the pole. There are extreme changes in the direction and magnitude of the force within fractions of a second – and these fluctuations can only be captured properly by a measuring instrument that has a wide measurement range, high natural frequency and outstanding dynamic sensitivity.

As an international expert on sports biomechanics, Professor Liu emphasizes the great importance of this project: "In conjunction with optical measurement systems, force plates from Kistler have given us a complete picture of the kinematics and dynamics of the athlete throughout the entire sequence of a pole vault. Based on the data we have obtained, we're able to carry out technical analyses, give training recommendations, and compile an accurate model of the movements and performance of each individual athlete."