Mehdizadeh Sina, Arshi Ahmed Reza, Davids Keith
a Biomechanics and Sports Engineering Group, Faculty of Biomedical Engineering , Amirkabir University of Technology , Tehran , Iran.
Eur J Sport Sci. 2014;14(8):791-8. doi: 10.1080/17461391.2014.905986. Epub 2014 Apr 10.
A number of studies have investigated effects of speed on local dynamic stability of walking, although this relationship has been rarely investigated under changing task constraints, such as during forward and backward running. To rectify this gap in the literature, the aim of this study was to investigate the effect of running speed on local dynamic stability of forward and backward running on a treadmill. Fifteen healthy male participants took part in this study. Participants ran in forward and backward directions at speeds of 80%, 100% and 120% of their preferred running speed. The three-dimensional motion of a C7 marker was recorded using a motion capture system. Local dynamic stability of the marker was quantified using short- and long-term largest finite-time Lyapunov exponents (LyE). Results showed that short-term largest finite-time LyE values increased with participant speed meaning that local dynamic stability decreased with increasing speed. Long-term largest finite-time LyEs, however, remained unaffected as speed increased. Results of this study indicated that, as in walking, slow running is more stable than fast running. These findings improve understanding of how stability is regulated when constraints on the speed of movements is altered. Implications for the design of rehabilitation or sport practice programmes suggest how task constraints could be manipulated to facilitate adaptations in locomotion stability during athletic training.
许多研究调查了速度对步行局部动态稳定性的影响，尽管在诸如向前和向后跑步等不断变化的任务限制条件下，这种关系很少被研究。为了弥补文献中的这一空白，本研究的目的是调查跑步速度对跑步机上向前和向后跑步局部动态稳定性的影响。15名健康男性参与者参与了本研究。参与者以其偏好跑步速度的80%、100%和120%的速度向前和向后跑步。使用运动捕捉系统记录C7标记物的三维运动。使用短期和长期最大有限时间李雅普诺夫指数（LyE）对标记物的局部动态稳定性进行量化。结果表明，短期最大有限时间LyE值随参与者速度增加而增加，这意味着局部动态稳定性随速度增加而降低。然而，长期最大有限时间LyE值在速度增加时保持不变。本研究结果表明，与步行一样，慢跑比快跑更稳定。这些发现增进了对运动速度限制改变时稳定性如何调节的理解。对康复或运动实践计划设计的启示表明了如何操纵任务限制以促进运动训练期间运动稳定性的适应。
