The aim of this study was to investigate the activity of the 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 electromyography (EMG) data of each muscle during AH were normalized as a percentage of MVC. During AH in all four starting positions, significant differences were found in the EMG activity of RA, EO, and TrA/IO (p<0.001). The TrA/IO exhibited the highest while the RA exhibited the lowest EMG activity. Among the four different starting positions, only the TrA/IO showed significant difference in mean EMG activity (p<0.001). The results suggest that all four starting positions can facilitate TrA/IO activity with minimal activity from RA and EO.