Electromyographic Response of the Abdominal Musculature to the Abdominal Crunch Exercise Utilizing the Hollowing Maneuver

Abstract

PURPOSE: The purpose of this study was to determine the impact of the hollowing maneuver on the activation of the abdominal musculature as measured by electromyogrphic recordings. METHODS: The subjects consisted of twenty-one young and apparently healthy individuals: age 20.5 + 1.5 years, height 177.6 + 7.5 cm, weight 75.205 + 11.684 kg, body fat 12.4 + 5.0 % for the males (n=11),and age 20.6 + 1.2 years, height 166.5 + 5.8 cm, weight 55.806 + 6.787 kg, body fat 17.0 + 4.9 % for the females (n=10). The surface electrodes were placed on the right side of the body over the upper rectus abdominis, lower rectus abdominis, internal oblique, external oblique, and at the rectus femoris. The subjects performed one five-second isometric crunch while EMG activity was recorded. After the initial testing session, the subjects were instructed on how to perform the hollowing maneuver (pull umbilicus in toward the spine, exhale slighting by contracting the abdominal muscles). After the subjects demonstrated proficiency in performing the hollowing maneuver, they were cleared to go and instructed to practice the technique each day during the next week. The second test took place one-week after the first test. RESULTS: There were no statistically significant differences between the two exercises when measured in the rectus femoris, or in the upper rectus abdominis. Statistically significant differences were noted in the lower rectus abdominis (183.73 + 116.23 μV vs. 119.50 + 67.45 μV), internal obliques (158.02 + 94.22 µV vs. 118.39 + 98.22 μV), and external obliques (157.73 + 93.20 μV vs. 91.01 + 66.45 μV), as measured while performing the regular crunch and the crunch with performing the hollowing maneuver, respectively. CONCLUSION: Based on the results of this study, it appears that the hollowing maneuver causes a net decrease in EMG activity of the abdominal musculature.