Spatial-temporal parameters,pelvic and lower limb movements during gait in individuals with reduced passive ankle dorsiflexion

BackgroundProper ankle dorsiflexion range of motion (ADF-ROM) allows the anterior roll of the tibia relative to the foot during the midstance phase of gait, which contributes to forward movement of the body. Individuals with reduced passive ADF-ROM may present altered movement patterns during gait due to an inefficient anterior tibial roll over the support foot during the stance phase.Research question: What is the influence of reduced passive ADF-ROM on the pelvic and lower limb movements and spatiotemporal parameters during gait?MethodThirty-two participants divided into two groups according to the degree of passive ADF-ROM—less than 10° (lower ADF-ROM group) or greater than 15° (higher ADF-ROM group) —were subjected to gait assessment using a three-dimensional motion analysis system. Independent t-tests were used to compare the pelvic and lower limb movements and spatiotemporal gait parameters between the groups on this cross-sectional study.ResultsThe lower ADF-ROM group had shorter step length, lower peak of pelvic ipsilateral rotation angle, and lower hip and knee maximum flexion angles in the stance phase (p < 0.05). In addition, the peaks of the ankle and forefoot-rearfoot dorsiflexion angles were smaller in the reduced ADF-ROM group (p < 0.05). The between-group differences presented effect sizes varying from moderate to large.SignificanceIndividuals with reduced passive ADF-ROM presented reduced foot and ankle dorsiflexion, knee and hip flexion, and pelvis rotation movements and shorter step length during gait. However, no differences in foot pronation were noted between groups. Therefore, individuals with reduced passive ADF-ROM present alterations in the lower limb and pelvic movements during gait.     

小学阶段超重/肥胖儿童平地行走的运动学分析

目的 通过比较小学阶段超重/肥胖儿童和正常儿童平地行走时的运动学参数,探讨超重/肥胖对儿童步态的影响。方法 选取40名超重/肥胖儿童(年龄(9.6±1.72)岁;身高(142.16±12.19) cm;身体质量指数（BMI）(24.32±2.96) kg/m2)和50名正常体重儿童(年龄(10.26±0.72)岁;身高(139.0±7.50) cm; BMI(17.08±1.25) kg/m2)为研究对象,受试者赤足以自己感觉舒适的常速自然行走在长10 m的跑道,共3次;使用常速摄像机进行平面定点拍摄,采集他们平地自然行走时的图像,通过视迅录像解析系统获得步长、下肢关节角度等运动学指标;数据采用SPSS 16.0进行统计学处理,受试者各项指标左右侧的比较采用配对t检验,两组儿童的各项指标比较采用独立样本t检验,P<0.05表示结果有显著性差异。结果 （1）对于相对步长,超重/肥胖儿童（0.44±0.001)与正常儿童显著不同（0.45±0.001）(P<0.05)。（2）足跟着地阶段,左髋及左、右膝在矢状面上的角度,超重/肥胖儿童（左髋(165.36±5.29)°,左膝(178.82±5.51)°,右膝(177.84±5.25)°）与正常儿童（左髋(161.99±4.28)°,左膝(174.67±4.91)°,右膝(174.67±4.91)°）显著不同(P<0.05);足跟蹬伸阶段,矢状面上的左踝关节角,超重/肥胖儿童（(121.73±8.03)°）与正常儿童（(118.44±6.70)°）显著不同(P<0.05)。结论 自然行走过程中,超重/肥胖儿童比正常儿童相对步长显著减小;足跟着地阶段,超重/肥胖儿童在矢状面上左髋和左右膝关节角显著大于正常儿童;足蹬伸阶段,超重/肥胖儿童在矢状面上的左踝关节角显著大于正常儿童。这些变化可能会对超重/肥胖儿童的下肢功能造成一定的影响。     

Altered astronaut lower limb and mass center kinematics in downward jumping following space flight

Astronauts exposed to the microgravity conditions encountered during space flight exhibit postural and gait instabilities upon return to earth that could impair critical postflight performance. The aim of the present study was to determine the effects of microgravity exposure on astronauts’ performance of two-footed jump landings. Nine astronauts from several Space Shuttle missions were tested both preflight and postflight with a series of voluntary, two-footed downward hops from a 30-cm-high step. A video-based, three-dimensional motion-analysis system permitted calculation of body segment positions and joint angular displacements. Phase-plane plots of knee, hip, and ankle angular velocities compared with the corresponding joint angles were used to describe the lower limb kinematics during jump landings. The position of the whole-body center of mass (COM) was also estimated in the sagittal plane using an eight-segment body model. Four of nine subjects exhibited expanded phase-plane portraits postflight, with significant increases in peak joint flexion angles and flexion rates following space flight. In contrast, two subjects showed significant contractions of their phase-plane portraits postflight and three subjects showed insignificant overall changes after space flight. Analysis of the vertical COM motion generally supported the joint angle results. Subjects with expanded joint angle phase-plane portraits postflight exhibited larger downward deviations of the COM and longer times from impact to peak deflection, as well as lower upward recovery velocities. Subjects with postflight joint angle phase-plane contraction demonstrated opposite effects in the COM motion. The joint kinematics results indicated the existence of two contrasting response modes due to microgravity exposure. Most subjects exhibited “compliant“ impact absorption postflight, consistent with decreased limb stiffness and damping, and a reduction in the bandwidth of the postural control system. Fewer subjects showed “stiff“ behavior after space flight, where contractions in the phase-plane portraits pointed to an increase in control bandwidth. The changes appeared to result from adaptive modifications in the control of lower limb impedance. A simple 2nd-order model of the vertical COM motion indicated that changes in the effective vertical stiffness of the legs can predict key features of the postflight performance. Compliant responses may reflect inflight adaptation due to altered demands on the postural control system in microgravity, while stiff behavior may result from overcompensation postflight for the presumed reduction in limb stiffness inflight. Received: 13 February 1996 / Accepted: 14 April 1997