The Effects of Wearing the Pregnancy Simulation Jacket on Kinematics and EMG Activity of Lower Extremity during Deep Squatting

Abstract

Background During pregnancy, the body’s center of gravity shifts forward, leading to increased posture fluctuations and anterior-posterior imbalance. Pregnant women often squat deeply in particular when handling objects on the floor, because they are not able to bend forward from the trunk. Therefore, it is important to understand how postural muscles are controlled to maintain balance. Objectives The purpose of the study was to show how wearing a pregnancy simulation jacket affects kinematic changes and muscle activity of the lower extremities during deep squatting, one of the daily activities of many pregnant women, and to suggest risk factors and effective strategies for pregnant women to use in their daily activities. Methods In this study, a pregnancy simulation jacket was worn by 19 healthy 20- to 30-year-old women to approximate the increased body weight associated with pregnancy. The subjects' erector spinae (ES), rectus femoris (RF), tibialis anterior (TA), gastrocnemius (GCM), and extensor digitorum brevis (EDB) muscle activities and kinematics of the lower extremities were measured using ImageJ. Results Significant differences were observed in RF (18.12 ± 14.57 vs. 23.61 ± 19.22, p = 0.022), TA (35.76 ± 19.47 vs. 45.86 ± 22.48, p = 0.017), and EDB (59.71 ± 31.19 vs. 65.02 ± 29.56, p = 0.027) muscle activity after wearing the pregnancy simulation jacket (WPJ) compared to before wearing the jacket (non-WPJ). When in a deep squatting position, the angle of the hip joint is significantly increased, resulting in a significantly increased distance from the raised heel to the floor under the WPJ condition relative to the non-WPJ condition. However, no significant differences were observed in ES muscle activity. Conclusions Pregnant women can make an epidemiological change, as shown in this study, as part of a protective strategy to avoid stress on the lower back caused by pregnancy-related weight gain.