Strength asymmetry can be detrimental to athlete performance and may lead to injury. The countermovement jump (CMJ) can be used to measure strength asymmetry via shear force production. The reliability of parameters and effects of asymmetry and shear force production on vertical CMJ performance were evaluated in a study with 15 university-level sprint and high jump athletes (m = 11, f = 4). The athletes performed three CMJs on two occasions, separated by 1 week. Tri-axial ground reaction force (GRF) was recorded using two force platforms embedded within a bespoke weight training area. Key performance metrics were calculated in real-time describing total CMJ performance, asymmetry and shear force production. Changes in the means and coefficients of variation (CV) were used to express reliability. Twenty-six parameters from the Total analysis and 21 Asymmetry analysis parameters showed a CV lower than 10%. Temporal and kinetic variables describing Asymmetry analysis highlight a lower CV compared with equivalent parameters derived from Total analysis. Shear parameters show high levels of CV compared with Total analysis and Asymmetry analysis. The measures of asymmetry calculated using methods described in this work were shown to be reliable for monitoring CMJ performance. No significant negative relationships were found between measures of asymmetry or shear force and traditional performance metrics in the CMJ (e.g. jump height, specific peak power and peak force). Further work is required to identify the potential of reducing asymmetry on CMJ performance.

力量不对称可能会损害运动员的表现，并可能导致受伤。反向运动跳跃（CMJ）可用于通过产生剪切力来测量强度不对称性。在15名大学级别的短跑运动员和跳高运动员（m  = 11，f）中进行的一项研究中评估了参数的可靠性以及不对称性和剪切力产生对垂直CMJ性能的影响 = 4）。运动员两次进行了三个CMJ，相隔1周。三轴地面反作用力（GRF）是使用嵌入在定制重量训练区域内的两个测力平台记录的。实时计算关键性能指标，以描述CMJ的总体性能，不对称性和剪切力产生。均值和变异系数（CV）的变化用于表示可靠性。总计分析中的26个参数和21个非对称性分析参数显示CV低于10％。时空和动力学变量描述了不对称分析突出了较低的CV相比，从全面分析得出的等效参数。剪切参数显示与总量分析和不对称分析。使用这项工作中描述的方法计算出的不对称性量度对于监控CMJ性能是可靠的。在不对称性或剪力的度量与CMJ中的传统性能度量（例如，跳跃高度，比峰值功率和峰值力）之间没有发现显着的负相关关系。需要进一步的工作来确定减少不对称性对CMJ性能的潜力。