Effect of Breathing Pattern and Posture on Abdominal Muscle Activation and Intra-abdominal Pressure

Abstract We aimed to examine the association between several breathing patterns and postures on abdominal muscle activation and intra-abdominal pressure (IAP). Fourteen healthy men performed four active breathing tasks: quiet nasal breathing (Q-Bre), nasal diaphragmatic breathing (Dia-Bre), completely forced expiration (Forced-Expi), and exertional nasal inhalation with abdominal muscles in isometric contraction (Exertion-Inspi) in the elbow-toe and supine posture. Breathing volume, IAP, and transverse abdominis-internal oblique muscle (TrA-IO) and external oblique muscle (EO) activity were recorded. Abdominal muscle activity and IAP were significantly associated with breathing pattern and postures during the expiratory phase. In the inspiratory phase, TrA-IO activity were significantly associated with breathing pattern and EO activity with posture. TrA-IO activity significantly increased in Forced-Expi in the supine posture (47.6% of the maximum voluntary contraction) and Exertion-Inspi in the elbow-toe posture (35.7%), while no differences were found for Dia-Bre or Q-Bre (<20%). EO activity increased in the elbow-toe posture (22.5–30.6%) compared with that in the supine posture (<5%) for all breathing tasks. IAP values were low for all tasks (<15%) except Forced-Expi (24.9%). Breathing pattern, including posture, is a crucial element for determining abdominal muscle activity in exercise instruction.