Electromyographic analysis of abdominal muscles during abdominal bracing and hollowing among six different positions

Abstract

Abdominal bracing exercise is used to enhance all abdominal muscle activity. There are two methods of abdominal bracing— “activate the abdominal muscles without hollowing the lower abdomen” and “activate the abdominal muscles while inflating the lower abdomen”. Although the latter method is widely used in athletic fitness coaching, the electromyographic activities of the abdominal muscles in this method have not been measured yet. This study aimed to clarify the electromyographic activity of all abdominal muscles during abdominal bracing using the latter method of “activating the abdominal muscles while inflating the lower abdomen”. Thirteen healthy men (age: 22 ± 2 years) participated in this study. Transversus abdominis (TrA), internal oblique (IO), external oblique (EO), and rectus abdominis (RA) electromyography was recorded using an intramuscular fine wire and surface electrodes. The participants performed abdominal bracing and hollowing for 5 s (seconds) in six different positions. The electromyographic data during trials were calculated as a percentage of maximal voluntary isometric contraction (%MVIC). A two-way ANOVA was used to compare the %MVIC of each trunk muscle between abdominal bracing and hollowing among the six different positions. In TrA electromyography, there was no difference between abdominal bracing and hollowing. On the other hand, the activities during abdominal hollowing were significantly higher than those during abdominal bracing in IO and EO (p < 0.05). In RA, the activities during abdominal bracing were significantly higher than those during abdominal hollowing (p < 0.05). Abdominal bracing under the method of inflating the lower abdomen is not recommended for high activity of the IO and EO.

Keywords

• abdominal muscles
• electromyography
• abdominal bracing
• abdominal hollowing