Trunk motion and gait characteristics of pregnant women when walking: report of a longitudinal study with a control group

Wendy L Gilleard

doi:10.1186/1471-2393-13-71

Abstract

BackgroundA longitudinal repeated measures design over pregnancy and post-birth, with a control group would provide insight into the mechanical adaptations of the body under conditions of changing load during a common female human lifespan condition, while minimizing the influences of inter human differences. The objective was to investigate systematic changes in the range of motion for the pelvic and thoracic segments of the spine, the motion between these segments (thoracolumbar spine) and temporospatial characteristics of step width, stride length and velocity during walking as pregnancy progresses and post-birth.MethodsNine pregnant women were investigated when walking along a walkway at a self-selected velocity using an 8 camera motion analysis system on four occasions throughout pregnancy and once post birth. A control group of twelve non-pregnant nulliparous women were tested on three occasions over the same time period. The existence of linear trends for change was investigated.ResultsAs pregnancy progresses there was a significant linear trend for increase in step width (p = 0.05) and a significant linear trend for decrease in stride length (p = 0.05). Concurrently there was a significant linear trend for decrease in the range of motion of the pelvic segment (p = 0.03) and thoracolumbar spine (p = 0.01) about a vertical axis (side to side rotation), and the pelvic segment (p = 0.04) range of motion around an anterio-posterior axis (side tilt). Post-birth, step width readapted whereas pelvic (p = 0.02) and thoracic (p < 0.001) segment flexion-extension range of motion decreased and increased respectively. The magnitude of all changes was greater than that accounted for with natural variability with re testing.ConclusionsAs pregnancy progressed and post-birth there were significant linear trends seen in biomechanical changes when walking at a self-determined natural speed that were greater than that accounted for by natural variability with repeated testing. Not all adaptations were resolved by eight weeks post birth.

Highlights

A longitudinal repeated measures design over pregnancy and post-birth, with a control group would provide insight into the mechanical adaptations of the body under conditions of changing load during a common female human lifespan condition, while minimizing the influences of inter human differences
The mean changes during pregnancy were greater than the natural variability associated with retesting as indicated by the standard error of the measurement (SEM), and there was no significant reversal of this trend by eight weeks post-birth (Tables 3 and 4)
The study aimed to investigate the linear trends for change in the range of motion of the thoracic and pelvic segments and thoracolumbar spine, and the temporospatial characteristics of velocity, stride length and step width for walking at a self-determined natural speed as pregnancy progressed and in the early post birth period using a longitudinal retest design

Summary

Introduction

A longitudinal repeated measures design over pregnancy and post-birth, with a control group would provide insight into the mechanical adaptations of the body under conditions of changing load during a common female human lifespan condition, while minimizing the influences of inter human differences. The objective was to investigate systematic changes in the range of motion for the pelvic and thoracic segments of the spine, the motion between these segments (thoracolumbar spine) and temporospatial characteristics of step width, stride length and velocity during walking as pregnancy progresses and post-birth. Wu et al [11] found that for pregnant women the range of motion amplitudes in the transverse plane of the pelvis and thoracic segments, and thoracolumbar spine were similar to a control nulliparous group, the intra-individual standard deviations were significantly smaller. The within group variability may have precluded finding a significant difference in amplitude a consistent reduction in comparison to the control group was noted [11]

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