Comparison between the Ki-hap technique and verbal encouragement on activation of abdominal muscles in healthy participants

The aim of this study was to investigate the comparison between a Ki-hap, defined as a psyching-up technique, and verbal encouragement, defined as a verbal command by a third party, on abdominal muscle activation during performance of the crunch exercise in healthy participants. Ninety participants were randomly allocated to the following three groups: crunch only exercise group (CG, n1 = 30), crunch exercise with Ki-hap group (CKG, n2 = 30), and crunch exercise with Ki-hap and verbal encouragement group (CKVG, n3 = 30). The interventions were conducted over three trials with each group, and measurements involving each participant, were performed by a single examiner. The activation of the rectus abdominis (RA), external oblique (EO), and internal oblique (IO) muscles were evaluated using electromyography (EMG) during performance of the crunch exercise by the CG, CKG, and CKVG. Our results showed a significantly greater increase in the EMG patterns of all muscles during performance of the crunch exercise in the CKG (p < 0.05) compared to those in the CG and CKVG. The results also showed that there was a significantly greater increase in the activation of the EO and IO muscles in the CKVG (p < 0.05) compared with that in the CG. These findings demonstrated that the addition of the Ki-hap technique and verbal encouragement, during performance of the crunch exercise, improves activation of the abdominal muscles.