Minimizing between-limb asymmetries during running is often a goal of training, as increased asymmetries are related to decreased efficiency and increased energy expenditure. However, it is unknown if asymmetries change with increased running exposure or are related to actual race performance. The purpose of this study was to determine (1) if pre-season asymmetries changed year-to-year among collegiate cross country runners, and (2) if these asymmetries were associated with within-season personal records (PRs). Pre-season biomechanical test results and race performance data were analyzed for 54 unique runners (28 female) across six seasons, totaling 152 assessments (age: 19.1 (0.9) years, height: 1.71 (0.10) m, weight: 61.7 (7.7) kg (values = mean [standard deviation])). Biomechanical asymmetries included ground reaction forces; ground contact time; base of gait; foot inclination angle; and peak hip flexion, hip extension, hip adduction, pelvic drop, knee flexion, and ankle dorsiflexion. Year of collegiate eligibility was used to quantify training exposure. Asymmetries during running did not change across years of eligibility (p ≥ 0.12), except propulsive impulse, which decreased over time (p = 0.03). PR times were faster with decreased propulsive impulse asymmetry and increased AVLR and peak ankle dorsiflexion asymmetries. This is the first study to assess longitudinal asymmetries over time and provide potential targets for interventions aimed at modifying asymmetries to improve performance.

中文翻译：

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大学生越野跑者跑步步态不对称的纵向变化及其与个人记录比赛时间的关系

在跑步过程中尽量减少四肢之间的不对称通常是训练的目标，因为不对称的增加与效率降低和能量消耗增加有关。然而，不对称性是否会随着跑步接触的增加而改变，或者与实际比赛表现有关，这是未知的。本研究的目的是确定 (1) 大学越野跑者的季前不对称是否逐年发生变化，以及 (2) 这些不对称是否与赛季内个人记录 (PR) 相关。对六个赛季中 54 名独特跑步者（28 名女性）的季前生物力学测试结果和比赛表现数据进行了分析，共计 152 项评估（年龄：19.1 (0.9) 岁，身高：1.71 (0.10) 米，体重：61.7 (7.7) kg（值 = 平均值 [标准偏差]））。生物力学不对称包括地面反作用力；地面接触时间；步态基础；脚倾角；和峰值髋关节屈曲、髋关节伸展、髋内收、骨盆下垂、膝关节屈曲和踝关节背屈。大学资格年份用于量化培训暴露。跑步期间的不对称性在资格年限中没有改变（p ≥ 0.12），除了推进冲动，随着时间的推移而减少（p = 0.03）。PR 时间随着推进脉冲不对称性的减少和 AVLR 的增加和踝关节背屈不对称峰值的增加而更快。这是第一项评估随时间推移的纵向不对称性并为旨在改善不对称性以提高绩效的干预措施提供潜在目标的研究。