Analysis of ground reaction force in gait during different phases of pregnancy

During pregnancy there are increased biomechanical demands on women affecting gait parameters. The purpose of this study was to analyze changes in vertical ground reaction force (GRF), normalized by body mass, during advancing phases of pregnancy. Nine pregnant subjects participated in this study at three pregnancy stages. To determine in-shoe pressure distribution Pedar Insole System was used (100 Hz). Analysis was done on 200 steps cycles of treadmill walking at the velocity of 0.83 m·s-1. To compare the differences of GRFs in maximal weight acceptance, middle stance and push-off phase and time to reach these forces among three pregnancy stages, repeated-measures ANOVA was performed to obtain partial eta-squared values to measure the effect size (η>.10). To interpret the overall mean differences between the three pregnancy stages Cohen’s d was applied (d>.20). Altered gait pattern during advancing phases of pregnancy demonstrated in the current study by a significant decrease in force of maximal weight acceptance and an increase in main time variables of the step is suggested to be a protective mechanism against overloading the contact area of the foot despite the increase in body mass