Acute Effects Of Gait Change During Simulated Pregnancy Using The Empathy Belly®

Abstract

An estimated 2 million births occur every year in the United States. During the 9 months of pregnancy a number of changes occur to the mother's body, particularly to mass and mass distribution, which can noticeably affect balance and gait. To date only one study has looked at gait mechanics and pregnancy. PURPOSE: To understand what gait changes occur during pregnancy by simulating load carriage during the third trimester of pregnancy using the Empathy Belly® (EB). METHODS: Sixteen females between the ages of 18-30 volunteered for the study. All subjects participated in a standard gait analysis under three different conditions: 1) self selected intentional speed (CN), 2) self selected intentional speed with EB (IEB) and 3) preferred speed with the EB (PEB). The EB weighed 28 lbs resembling an average gain for a 36 week pregnancy. Motion analysis and force platform data were collected to calculate joint kinematics and kinetics of the right lower extremity. Data were normalized to the each subject's height and unloaded body mass. The variables of interest for the study were peak sagittal plane kinematics and kinetics along with peak vertical and anteroposterior ground reaction forces. A repeated measures ANOVA with significance level set at p<0.05 was performed to analyze the data. RESULTS: Subjects exhibited increased peak vertical (20% > CN) and anteroposterior (19% & 24% > CN) peak ground reaction forces along with increased peak dorsiflexion moment (15% > CN), peak plantarflexion moment (17% > CN), peak knee extension moment (16% > CN), and peak knee flexion (2 deg > CN) for the IEB compared to the other two conditions. Interestingly, a reduced peak hip extension (3 deg < CN) and peak hip extension moment (10% < CN) was observed during the PEB when compared to the other two conditions. CONCLUSIONS: Considerable changes in gait occur during an acute exposure to the EB. Sagittal plane kinetics and kinematics increase at the knee and ankle when the additional 28 lb displaced the center of gravity in an anteroinferior direction and when walking at a self-selected intentional walking speed. Walking in the PEB condition, which is likely to correlate to changes in gait during the last trimester of pregnancy, led to an under utilization of the hip extensors. Specific post partum training should not neglect this potential problem area.