Activation of Abdominal Muscles during Abdominal Hollowing in Four Different Positions

Abstract

[Purpose] This study examined the activities of the rectus abdominis (RA), external abdominal oblique (EO), transversus abdominis and internal abdominal oblique (TrA/IO) while abdominal hollowing (AH) was performed in four different positions (crook lying, prone lying, four-point kneeling, wall support standing). [Subjects] Experiments were conducted on 36 healthy male adults (mean age=24.44 years) who voluntarily agreed to participate in the experiments. [Methods] Each subject was instructed regarding maximal voluntary contractions (MVC) and AH. While the MVC and AH of individual muscles were being performed, the activity of the muscles was measured using surface electromyography (EMG). The activity of the muscles while performing AH was normalized to percentages of MVC. [Results] TrA/IO showed significant differences among the positions and showed the highest muscle activity for prone lying. [Conclusion] The contraction of the TrA/IO was shown to be the highest muscle activity in prone lying. Therefore, we consider that various kinds of technique can eliminate EO activity during performing AH in prone lying.