School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, Leicestershire, UNITED KINGDOM.
National Centre for Sport and Exercise Medicine-East Midlands, Loughborough, Leicestershire, UNITED KINGDOM.
Med Sci Sports Exerc. 2018 Jun;50(6):1241-1248. doi: 10.1249/MSS.0000000000001560.
The aim of this study was to investigate the effect of altering preferred running speed by ±20% on kinetic asymmetry.
Three-dimensional motion analysis and force data were acquired from 15 healthy males (age, 27 ± 4.6 yr; height, 1.81 ± 0.09 m; mass, 80.4 ± 12.4 kg) during their preferred running speed and at ±20% of this speed. Three-tesla magnetic resonance images were used to measure Achilles tendon cross-sectional area and moment arm, for use in calculation of tendon stress. Kinetic and tendon stress asymmetry were subsequently calculated in each condition using the symmetry index.
Across all joints and conditions, the average asymmetry of peak moments was between ±6%, but higher individual values were observed. There was no effect of speed on the magnitude of asymmetry. Ground contact times, vertical ground reaction forces, and support and ankle moments (maximum absolute asymmetry, 9%) were more symmetrical than hip and knee moments (up to 18%). Individual joint contribution to support moment and positive work were similar in both limbs, and ankle and hip compensatory interactions were observed with alterations in running speed. Achilles tendon stress increased with increased running speed, with higher stress in the preferred limb; asymmetry in tendon stress was not related to asymmetry in vertical ground reaction forces.
Results show small effects of altering running speed on kinetic asymmetry, but responses are individual specific with interactions occurring between joints to maintain overall movement symmetry. Further research is needed to understand the mechanical and neuromuscular mechanisms underpinning these compensations.
本研究旨在探讨改变 preferred running speed（预设跑步速度）±20%对动力学不对称性的影响。
15 名健康男性（年龄 27±4.6 岁；身高 1.81±0.09 米；体重 80.4±12.4 千克）在预设跑步速度和 ±20%预设速度下进行三维运动分析和力数据采集。使用 3 特斯拉磁共振成像测量跟腱横截面积和力臂，用于计算肌腱应力。随后，使用对称性指数计算每个条件下的动力学和肌腱应力不对称性。
在所有关节和条件下，峰值力矩的平均不对称性在±6%之间，但观察到更高的个体值。速度对不对称性的大小没有影响。着地时间、垂直地面反作用力以及支撑和踝关节力矩（最大绝对不对称性为 9%）比髋关节和膝关节力矩（高达 18%）更对称。在两条腿中，支撑力矩和正功的各个关节贡献相似，并且随着跑步速度的改变，观察到踝关节和髋关节的补偿相互作用。跟腱应力随跑步速度的增加而增加，预设腿的应力更高；跟腱应力的不对称性与垂直地面反作用力的不对称性无关。
结果表明，改变跑步速度对动力学不对称性的影响很小，但个体的反应是特定的，关节之间会发生相互作用，以保持整体运动的对称性。需要进一步研究来了解这些补偿的力学和神经肌肉机制。
