目的 从线性和非线性两个角度探究人体站立稳定调控策略。 方法 招募 16 名健康男性受试者,在平衡台完成 30 s 正常站立、闭眼站立以及在泡沫垫上睁眼和闭眼站立,通过时空参数、轨迹近似熵和小波变换分析不同干扰因素站立时足底压力中心(center of pressure, COP)轨迹的线性及非线性特征,采用视觉×本体感觉重复测量方差分析比较干扰情况下(视觉干扰、本体感觉干扰和视觉、本体感觉共同干扰)与正常站立情况下 COP 轨迹线性及非线性特征差异。 结果 在线性指标中,闭眼站立、不稳定站立和闭眼不稳定站立相比于正常站立时 COP 轨迹长度、轨迹速率和 C90 面积均增加( P < 0. 05),3 种干扰方式下的 C90 偏角以及前后( anteroposterior,AP)、内外(mediolateral,ML)方向平均偏移量相比于正常站立无明显变化(P>0. 05)。 在非线性指标中,在 ML 和 AP 两个方向,闭眼站立、不稳定站立和闭眼不稳定站立相比于正常站立 COP 轨迹的近似熵差异均无差异(P>0. 05);频域指标的 ML 方向,视觉干扰使中频、低频和次低 3 个频段的能量权重升高(P<0. 05),超低频能量权重降低(P<0. 05);本体感觉干扰时 3 个频段的能量权重相比于正常站立无差异(P>0. 05);在视觉、本体感觉共同干扰时,中频、低频和次低频能量权重增加(P<0. 05),超低频能量权重降低(P<0. 05);在频域指标的 AP 方向,视觉干扰后相比于正常站立次低频能量下降(P<0. 05)、超低频能量上升(P<0. 05);本体感觉干扰和视觉、本体感觉共同干扰中频、低频和次低频能量权重均上升(P<0. 05),超低频能量权重下降(P<0. 05)。 结论 对于健康人群,站立时人体以较低频段的闭环控制机制为主导,外界信号输入受到干扰并不会改变站立 COP 轨迹的复杂性,其中视觉信息干扰对 ML方向影响较为明显,本体感觉信息干扰对 AP 方向影响较为明显。 站立受到干扰时,开环控制机制的较高频段能量权重增加,身体的晃动幅度和速度变大。

Objective To explore the regulation strategy of human standing stability from linear and nonlinear perspectives. Methods Sixteen healthy male subjects were recruited and required to stand normally or stand with closed eyes, stand on foam pad with open eyes or closed eyes for a period of 30 s on the balancer. The linear and nonlinear characteristics of plantar COP (center of pressure) trajectory during standing with different interference factors were analyzed by spatio-temporal parameters, trajectory approximate entropy and wavelet transform. Visual × proprioceptive repeated measures ANOVA was used to compare the linear and nonlinear characteristics of COP trajectory between the interference condition (visual interference, proprioceptive interference and visual and proprioceptive interference) and normal standing. Results For linear index, the COP trajectory length, trajectory rate and C90 area during closed-eye standing, unstable standing and closed-eye unstable standing were all higher than those during normal standing (P<0.05). The average offset of C90 area and that in mediolateral (MP) and anteroposterior (AP) directions under three interference modes had no significant changes compared with that during normal standing (P>0.05). For nonlinear index, in MP and AP directions, there was no significant difference in approximate entropy between closed-eye standing, unstable standing and closed-eye unstable standing compared with that during normal standing pressure center track (P>0.05). For frequency domain index in MP direction, visual interference increased the energy weight of the intermediate frequency, low frequency and sub-low frequency bands (P<0.05), and decreased the ultra-low frequency energy weight (P<0.05). The energy weight of three frequency bands during proprioceptive interference was not different from that of normal standing (P>0.05), while the energy weight of intermediate frequency, low frequency and sub-low frequency increased (P<0.05), while that of ultra-low frequency decreased (P<0.05). For frequency domain index in AP direction, the sub-low frequency energy decreased (P<0.05) and ultra-low frequency energy increased (P<0.05) after visual interference compared with that during normal standing. The energy weights of intermediate frequency, low frequency and sub-low frequency of proprioceptive interference, visual and proprioceptive interference increased (P<0.05), while that of ultra-low frequency decreased (P<0.05). Conclusions For healthy people, the closed-loop control mechanism of lower frequency band is dominant during standing, and the interference of external signal input will not change the complexity of COP trajectory, in which visual information interference has an obvious effect on ML direction, proprioceptive information interference has an obvious effect on AP direction. When standing is disturbed, the energy weight of higher frequency band of open-loop control mechanism increases, and shaking amplitude and speed of the body become larger.

河北省教育厅青年基金项目(SQ2021215),河北省高等学校科学技术研究项目(SQ2021215),河北省教育科学研究“十三五”规划课题(1703154),河北省科技支撑项目(16275709)