The role of the diaphragm during abdominal hollowing exercises.

This study investigated the surface electromyographical (EMG) profiles of the diaphragm, anterolateral abdominals and rectus abdominis during abdominal hollowing exercises (AHE) in 20 healthy subjects. Muscle activity was assessed at 1000Hz over two seconds in crook lying at three incremental loads above a baseline of 40mmHg monitored by a pressure biofeedback unit. EMG amplitude increased significantly above resting for all muscles during correct performance of AHE at 5mmHg. At 15mmHg, all subjects were deemed to have performed AHE incorrectly and both the diaphragm and rectus abdominis activity were significantly elevated (p < 0.05). This supports the concept that the diaphragm plays a significant role in motor control strategies used by subjects performing different forms of AHE.