Vertical stiffness and muscle strain in professional Australian football

Abstract

The purpose of this study was to establish if vertical stiffness was greater in professional Australian rules footballers who sustained a lower limb skeletal muscle strain compared to those who did not, and to establish if a relationship between age, or training history, and vertical stiffness existed. Thirty-one participants underwent weekly rebound jump testing on a force platform over two seasons. Vertical stiffness was calculated for injured players and the uninjured cohort 1 and 3 weeks prior to sustaining an injury and at the end of preseason. Eighteen athletes were in the “uninjured” cohort and 13 in the “injured” cohort. No significant difference in vertical stiffness was observed between groups (P = 0.18 for absolute stiffness; P = 0.08 for stiffness relative to body mass), within groups (P = 0.83 and P = 0.88, respectively) or for a time*cohort interaction (P = 0.77 and P = 0.80, respectively). No relationship between age and vertical stiffness existed (r = ?0.06 for absolute and relative stiffness), or training history and vertical stiffness (r = ?0.01 and 0.00 for absolute and relative stiffness, respectively) existed. These results and others lend to suggest that vertical stiffness is not related to lower limb muscle strain injury.     

基于假人仿真模型的冰雪运动生物力学教学实验设计北大核心

“理论力学”是力学、机械、航空航天等工科专业的核心必修课之一。然而,目前该课程的教学实验大多是原理演示或简单参数测量,不利于学生深刻理解专业知识、提升解决实际问题的综合创新能力。为解决上述难题,围绕人体运动这一典型的多刚体系统动力学问题,构建了基于假人仿真模型的自由式滑雪空中技巧运动生物力学教学实验,涵盖力学模型简化、拉格朗日方程构建、刚体惯性参数计算、动力学仿真软件应用等主要知识点和技能。该教学实验转化自“科技冬奥”重点研发计划的科研成果,具有前沿性、交叉性和综合探究性,有助于提升复合型拔尖跨学科人才的综合实践能力。