Abdominal muscle activity during the abdominal hollowing manoeuvre in the four point kneeling and prone positions

This study investigated the pattern of recruitment of the abdominal muscles during the abdominal hollowing manoeuvre (AHM), in four point kneeling and prone. Muscle activity was detected and recorded by surface electromyography (EMG), in 20 healthy subjects, 8 male and 12 female, aged between 19 and 30 during both maximal activity, and the AHM. The degree of activation during hollowing was expressed as a percentage of maximal. There was activity in the internal abdominal oblique (IO) during all hollowing manoeuvres, in both starting positions, whilst only two subjects showed any activity in rectus abdominis (RA). Simultaneous activity in IO and EO occurred both in four point kneeling (45% of the subjects) and especially in prone (75% of the subjects). Across both positions IO activity was significantly greater than EO. There was no significant difference in EO or IO activity comparing across positions. These results suggest that the AHM when performed in four point kneeling and prone always activates IO and rarely activates RA, whilst elimination of activity in EO is more difficult to achieve, particularly in prone. Isolated activity in the deep abdominal muscles may not always be achievable in these starting positions.