Amasay Tal, Suprak David N
Barry University, Miami Shores, FL, USA.
Western Washington University, Bellingham, WA, USA.
J Hum Kinet. 2022 Nov 8;84:53-63. doi: 10.2478/hukin-2022-0091. eCollection 2022 Oct.
A countermovement jump (CMJ) is common in sport and often time-constrained. Little is known about contributors to quickness in jumps. This study examined effective predictors of time to take-off and effects of the starting position on reaction time and take-off time in a countermovement jump performed for quickness from upright and squat positions. Forty-nine collegiate athletes performed CMJs for quickness from upright and squatting starting positions to 75% of their maximal jump height. Several variables were calculated from the kinetic data related to jump performance. Correlation and multiple regression were used to determine variables related and predictive of time to take-off under both conditions. Paired t-tests evaluated differences in reaction and take-off times between conditions. In the upright condition, an increasing rate of force development and force, and decreasing time variables, impulses, and countermovement depth were associated with shorter time to take-off. The time to take-off prediction included rates of force development, force, time, and impulse. In the squat condition, shorter time to take-off was associated with lesser time variables, eccentric impulse, force at the end of the eccentric phase, and countermovement depth, and a greater rate of force development, concentric impulse, peak power, peak force, and reaction time. The time to take-off prediction equation included time to the bottom of the countermovement, time to peak force, and peak power. Reaction and take-off times were longer in the upright condition. Quick jump efficiency may be improved by strategies to increase maximum strength and the eccentric rate of force development while decreasing countermovement depth and time to bottom.
反向纵跳（CMJ）在体育运动中很常见，且通常受时间限制。对于跳跃速度的影响因素知之甚少。本研究考察了起跳时间的有效预测指标，以及起始姿势对从直立和深蹲姿势进行快速反向纵跳时反应时间和起跳时间的影响。49名大学生运动员从直立和深蹲起始姿势进行CMJ，达到其最大跳跃高度的75%。从与跳跃表现相关的动力学数据中计算出几个变量。使用相关性分析和多元回归来确定两种条件下与起跳时间相关并可预测起跳时间的变量。配对t检验评估不同条件下反应时间和起跳时间的差异。在直立条件下，力量发展速率和力量增加，以及时间变量、冲量和反向运动深度减小，与较短的起跳时间相关。起跳时间预测指标包括力量发展速率、力量、时间和冲量。在深蹲条件下，较短的起跳时间与较小的时间变量、离心冲量、离心阶段结束时的力量以及反向运动深度相关，以及较大的力量发展速率、向心冲量、峰值功率、峰值力量和反应时间。起跳时间预测方程包括到达反向运动最低点的时间、到达峰值力量的时间和峰值功率。直立条件下的反应时间和起跳时间更长。通过增加最大力量和力量发展的离心速率，同时减小反向运动深度和到达最低点的时间的策略，可能会提高快速跳跃效率。
