Department of Neuromedicine and Movement Science, Faculty of Medicine and Health Sciences, NTNU, Centre for Elite Sports Research , Trondheim, Norway.
Olympiatoppen , Norway.
J Sports Sci. 2020 Sep;38(18):2155-2160. doi: 10.1080/02640414.2020.1776913. Epub 2020 Jun 16.
Imitation jumps are frequently used in training for ski jumping. Yet, the dynamics of these jumps differ considerably. Thus, the relevance of imitation jumps for ski jumping performance is not elucidated. The aim of this study was to investigate the relationship between the technical execution of imitation jumps and ski jumping performance level. We compared the imitation jumps of 11 ski jumpers of different performance levels using a Spearman correlation transform of time traces of the kinetics (measured using force cells and motion capture) of imitation jumps. The kinetic aspects that were related to performance centred on the moment arm of ground reaction force to the centre of mass before the onset of the push-off, angular momentum early in push-off, thigh angle during the main period of push-off and vertical velocity towards the end of push-off. We propose that the thigh angle may be a key element allowing high development of linear momentum while preparing for appropriate aerodynamic position. Furthermore, the findings suggest that the kinetic development prior to (and during) push-off is more important than the kinematic end state at take-off.
模仿跳跃在跳台滑雪训练中经常被使用。然而，这些跳跃的动力学特征差异很大。因此，模仿跳跃对跳台滑雪成绩的相关性尚不清楚。本研究的目的是调查模仿跳跃的技术执行与跳台滑雪成绩水平之间的关系。我们使用力传感器和运动捕捉测量的动力学时间轨迹的 Spearman 相关变换，比较了不同成绩水平的 11 名跳台滑雪运动员的模仿跳跃。与成绩相关的动力学特征主要集中在蹬伸开始前地面反作用力对质心的力臂、蹬伸早期的角动量、蹬伸主要阶段的大腿角度以及蹬伸结束时的垂直速度。我们提出，大腿角度可能是一个关键因素，它允许在准备合适的空气动力姿势的同时，很好地发展线性动量。此外，研究结果表明，在蹬伸之前（和期间）的动力学发展比起跳时的运动学终态更为重要。
