Abstract:
The aim of this study was to investigate recruitment pattern of surface electromyography (EMG) of rectus abdominis (RA), external abdominal oblique (EO), and transversus abdominis/internal abdominal oblique (TrA/IO) muscles during abdominal hollowing (AH) in four positions: crook lying. prone lying, four-point kneeling, and wall support standing. Thirty-two healthy participants, aged 21.3_+0.8 years were recruited. They were instructed to perform maximal voluntary contraction (MVC) and AH. The EMG data of each muscle during AH were normalized as a percentage of MVC. Significant differences were found in the EMG activity of RA, EO, and TrA/IO in all four starting positions (p < 0.001). The TrA/IO exhibited the highest while the RA exhibited the lowest EMG activity. The prone lying position appears to be the most appropriate position for performing AH. It showed the highest activity of TrA/IO with the lowest activity of RA. The means of Ra, EO, and TrA/IO during AH in prone lying were 1.35, 6.09, and 27.59 percent of MVC, respectively.
