*4.4. COM-COP Inclination Angles*

The medial COM-COP inclination angle may be a sensitive measure of gait stability [37]. Our study found that the ML-ROM and the peak medial COM-COP inclination angles were not significantly different under different conditions, and we inferred that changing heel-toe drop within a certain range does not change the ML stability of pregnant women in the third trimester of pregnancy. Our findings indicate that heel-toe drop affects the peak posterior COM-COP inclination angle in pregnant women in the third trimester and that NHS is significantly smaller in the peak posterior COM-COP inclination angle than NS., which may benefit the stability during the propulsion phase. Previous studies on NHS showed that foot contact angle and the angle of the ankle NHS are significantly larger than those of NS. This may indicate that wearing NHS may benefit stability in the front and rear directions. Of course, this change may be related to the slower walking speed of NHS, which has been shown to affect gait changes and COM movement [60–62].
