Virmavirta Mikko, Kivekäs Juha, Komi Paavo
Neuromuscular Research Center, Department of Biology of Physical Activity, University of Jyväskylä, Finland.
J Appl Biomech. 2011 Nov;27(4):375-9. doi: 10.1123/jab.27.4.375. Epub 2011 Aug 26.
The effect of skis on the force-time characteristics of the simulated ski jumping takeoff was examined in a wind tunnel. Takeoff forces were recorded with a force plate installed under the tunnel floor. Signals from the front and rear parts of the force plate were collected separately to examine the anteroposterior balance of the jumpers during the takeoff. Two ski jumpers performed simulated takeoffs, first without skis in nonwind conditions and in various wind conditions. Thereafter, the same experiments were repeated with skis. The jumpers were able to perform very natural takeoff actions (similar to the actual takeoff) with skis in wind tunnel. According to the subjective feeling of the jumpers, the simulated ski jumping takeoff with skis was even easier to perform than the earlier trials without skis. Skis did not much influence the force levels produced during the takeoff but they still changed the force distribution under the feet. Contribution of the forces produced under the rear part of the feet was emphasized probably because the strong dorsiflexion is needed for lifting the skis to the proper flight position. The results presented in this experiment emphasize that research on ski jumping takeoff can be advanced by using wind tunnels.
在风洞中研究了滑雪板对模拟跳台滑雪起跳时力-时间特性的影响。通过安装在风洞地面下方的测力板记录起跳力。测力板前后部分的信号被分别采集，以研究跳台滑雪运动员起跳过程中的前后平衡。两名跳台滑雪运动员进行了模拟起跳，首先在无风条件下以及各种有风条件下不使用滑雪板进行起跳。此后，使用滑雪板重复相同的实验。在风洞中，运动员使用滑雪板能够做出非常自然的起跳动作（类似于实际起跳）。根据运动员的主观感受，使用滑雪板进行模拟跳台滑雪起跳甚至比之前不使用滑雪板的试验更容易完成。滑雪板对起跳过程中产生的力的大小影响不大，但它们仍然改变了脚下的力的分布。脚部后方产生的力的贡献可能得到了强调，因为将滑雪板提升到合适的飞行位置需要强烈的背屈。本实验结果强调，利用风洞可以推动对跳台滑雪起跳的研究。
