By Kieran Haller, Laurin Paradise, and Elana Robinson-Lynch

Authors Haller, Robinson-Lynch, and Paradise in half sit-up position

Our group's experiment strove to compare the activity of stomach muscles when doing a sit up versus a 'crunch'. We were curious as to which abdominal exercises were more effective on different sections of the rectus abdominis, having heard conflicting opinions on this.

We used three subjects, between the ages of 18 and 19. Two were female, and one was male. A sit up is when a person raises their chest all the way to their knees before going back down to the lying position, whereas in a crunch a person only lifts their shoulders off the ground as if they were pulling their head towards their stomach rather then toward their knees. To understand where the greatest amount of muscle activity was, we decided to place electrodes along the second and fourth pairs of abdominal muscles. This way we can determine how high up on the rectus abdominis the muscle action was taking place. To keep fatigue from playing a factor in the experiment, the person alternates between the two exercises. After ten repetitions of each we switched subjects.

Authors Haller, Robinson-Lynch, and Paradise in full sit-up position

Each of the three subjects showed similarly inconclusive results overall. In the case of the lower abdominal muscles, two of the subjects exhibited slightly higher readings during the half sit-ups, and one of the subjects had a statistically significant increase during the half sit up. However, the other subject experienced a higher reading during the full sit-ups. The P-Values were as follows: 0.26 for Laurin; 0.14 for Elana; and 0.98 for Kieran. The standard deviations also varied depending on the activity. The upper abdominal muscles also didn’t display a consistently higher reading for either of the two conditions. In two of the subjects there were higher readings during the full sit-ups, however, one mean was only higher by less than ten microvolts, and in the other the readings also were not off by much. The P-Values were as follows: 0.24 for Laurin; 0.05 for Elana; and 0.96 for Kieran.

We found that there was not a significant difference between the muscle activity in the abdominals during full sit-ups as compared to half sit-ups. We think that had our study had more subjects, we may have found different results. Our results may have been altered due to the movement of the wires during the exercises. Further research studying other abdominals exercises may also be useful.