Department of Informatics and Sports, University of Pablo de Olavide , Sevilla, Spain.
J Sports Sci Med. 2010 Jun 1;9(2):282-7. eCollection 2010.
In most common bilateral landings of vertical jumps, there are two peak forces (F1 and F2) in the force-time curve. The combination of these peak forces and the high frequency of jumps during sports produce a large amount of stress in the joints of the lower limbs which can be determinant of injury. The aim of this study was to find possible relationships between the jump height and F1 and F2, between F1 and F2 themselves, and between F1, F2, the time they appear (T1 and T2, respectively) and the length of the impact absorption phase (T). Thirty semi-professional football players made five countermovement jumps and the highest jump of each player was analyzed. They were instructed to perform the jumps with maximum effort and to land first with the balls of their feet and then with their heels. All the data were collected using a Kistler Quattro Jump force plate with a sample rate of 500 Hz. Quattro Jump Software, v.1.0.9.0., was used. There was neither significant correlation between T1 and F1 nor between T1 and F2. There was a significant positive correlation between flight height (FH) and F1 (r = 0.584, p = 0.01) but no significant correlation between FH and F2. A significant positive correlation between F1 and T2 (r = 0.418, p < 0.05) and a significant negative correlation between F2 and T2 (r = -0.406, p < 0.05) were also found. There is a significant negative correlation between T2 and T (r = -0. 443, p < 0.05). T1 has a little effect in the impact absorption process. F1 increases with increasing T2 but F2 decreases with increasing T2. Besides, increasing T2, with the objective of decreasing F2, makes the whole impact absorption shorter and the jump landing faster. Key pointsIn the landing phase of a jump there are always sev-eral peak forces. The combination of these peaks forces and the high frequency of jumps during sports produces a large amount of stress in the joints of the lower limbs which can be determinant of injury.In the most common two-footed landings usually appear two peak forces (F1 and F2) in the force-time curve and the second one is usually related to injury's risk. In this article it is shown that increasing the time F2 appears decrease F2.Increasing landing times could be counterproductive with respect to the goals of the sport. In this article it is shown that increasing the time F2 appears makes, however, the whole impact absorption shorter in du-ration.
在大多数常见的双脚垂直跳跃着地阶段，力-时间曲线上会出现两个峰值力（F1 和 F2）。这些峰值力的组合以及运动中跳跃的高频次会在下肢关节产生大量的应力，这可能是造成损伤的决定因素。本研究旨在发现跳跃高度与 F1 和 F2 之间、F1 和 F2 之间、F1、F2 及其出现时间（分别为 T1 和 T2）与冲击吸收阶段长度（T）之间的可能关系。30 名半职业足球运动员进行了五次反向跳跃，分析了每位运动员的最高跳跃。他们被要求用最大的力量进行跳跃，先用脚掌着地，然后用脚跟着地。所有数据均使用 Kistler Quattro Jump 测力板以 500Hz 的采样率采集。Quattro Jump 软件，v.1.0.9.0. 用于分析数据。T1 与 F1 之间以及 T1 与 F2 之间均无显著相关性。飞行高度（FH）与 F1 呈显著正相关（r = 0.584，p = 0.01），但 FH 与 F2 无显著相关性。F1 与 T2 之间呈显著正相关（r = 0.418，p < 0.05），F2 与 T2 之间呈显著负相关（r = -0.406，p < 0.05）。T2 与 T 之间存在显著负相关（r = -0.443，p < 0.05）。T1 在冲击吸收过程中的影响较小。F1 随 T2 的增加而增加，但 F2 随 T2 的增加而减少。此外，为了降低 F2，增加 T2 会使整个冲击吸收阶段变短，跳跃着地更快。关键点：在跳跃着地阶段，通常会出现几个峰值力。这些峰值力的组合以及运动中跳跃的高频次会在下肢关节产生大量的应力，这可能是造成损伤的决定因素。在最常见的双脚着地中，力-时间曲线上通常会出现两个峰值力（F1 和 F2），第二个峰值力通常与受伤风险有关。本文表明，增加 F2 出现的时间会降低 F2。增加着地时间可能会对运动的目标产生反效果。本文表明，增加 F2 出现的时间会使整个冲击吸收阶段变短。
