Effect of trunk posture on external and internal oblique muscles' activities during forced expiration.

Introduction: The activities of external oblique (EO) and internal oblique (IO) muscles during forced expiration in a trunk-neutral posture are insufficient for muscle strengthening. Furthermore, these activities during forced expiration may be affected by trunk postures, which can change respiratory muscle activity. Therefore, this study aimed to evaluate the effects of trunk posture on the EO and IO muscles' activities during forced expiration.