Kim Ji-Won, Kwon Yuri, Jeon Hyung-Min, Bang Min-Jung, Jun Jae-Hoon, Eom Gwang-Moon, Lim Do-Hyung
The School of Biomedical Engineering, Konkuk University, Chungnju, 380-701, Korea.
The School of Biomedical Engineering, Konkuk University, Chungnju, 380-701, Korea Research Institute of Biomedical Engineering, Konkuk University, Chungnju, 380-701, Korea.
Biomed Mater Eng. 2014;24(6):2681-8. doi: 10.3233/BME-141085.
The purpose of this study was to investigate 1) the effect of feet distance on static postural balance and 2) the location of natural feet distance and its possible role in the relationship of feet distance and postural balance. Static balance tests were performed on a force platform for 100 s with six different feet distances (0, 5, 10, 15, 20, 25 cm). Measures of postural balance included mean amplitude of horizontal ground reaction force (GRF) as well as the mean distance and velocity of the center of pressure (COP). All measures were discomposed into anterioposterior and mediolateral directions. ANOVA and post-hoc comparison were performed for all measures with feet distance as an independent factor. Also measured was the feet distance at the natural stance preferred by each subject. All measures significantly varied with feet distance (p<0.001). Mean distance of COP showed monotonic decrease with feet distance. Mean amplitude of horizontal GRF as well as mean velocity of COP showed U-shaped pattern (decrease followed by increase) with the minimum at the feet distance of 15 cm or 20 cm, near which the natural feet distance of 16.5 (SD 3.8) cm was located. COP is regarded to be an approximation of the center of mass (hence the resultant performance of postural control) in an inverted pendulum model with the horizontal GRF ignored. On the other hand, horizontal GRF is the direct cause of horizontal acceleration of a center of mass. The present result on horizontal GRF shows that the effort of postural control is minimized around the feet distance of natural standing and implies why the natural stance is preferred.
1）双脚间距对静态姿势平衡的影响；2）自然双脚间距的位置及其在双脚间距与姿势平衡关系中可能发挥的作用。在测力平台上进行了100秒的静态平衡测试，测试时设置了六种不同的双脚间距（0、5、10、15、20、25厘米）。姿势平衡的测量指标包括水平地面反作用力（GRF）的平均幅度以及压力中心（COP）的平均距离和速度。所有测量指标均分解为前后方向和内外侧方向。以双脚间距为独立因素，对所有测量指标进行方差分析和事后比较。同时还测量了每个受试者自然站立姿势下的双脚间距。所有测量指标均随双脚间距显著变化（p<0.001）。COP的平均距离随双脚间距呈单调下降。水平GRF的平均幅度以及COP的平均速度呈U形模式（先下降后上升），在双脚间距为15厘米或20厘米时达到最小值，而自然双脚间距为16.5（标准差3.8）厘米，就在该范围附近。在忽略水平GRF的倒立摆模型中，COP被视为质心的近似值（因此也是姿势控制的综合表现）。另一方面，水平GRF是质心水平加速度的直接原因。目前关于水平GRF的结果表明，在自然站立的双脚间距附近，姿势控制的努力最小化，这也解释了为什么自然姿势更受青睐。
