Comparative analysis of rectus abdominis musculature activity while performing machine sit-ups vs bent-legged sit-ups

This study compared the bent-legged sit-up (BLS) to a sit-up movement pattern performed on an Eagle isotonic machine (EM). Thirty-three healthy individuals (17 men, 16 women, from 20 to 36 years of age) participated in this study. Electromyography (EMG) readings were measured bilaterally from the upper and lower portions of the rectus abdominis. Each subject performed both sit-up techniques for 3 sets x 5 repetitions. The EM utilized resistance plates 1, 3, 4 or 5 for three sets respectively. One factorial analysis of variance with repeated measures (ANOVA-RM) and a paired two tailed t-test were used to analyze the data. Results from this study showed significant differences that the BLS elicited a higher EMG activity as compared to the EM during the first two sets in all phases from the upper and lower rectus abdominis (p=.0001) using the paired two-tailed t-test. The ANOVA-RM also found the BLS elicited a significant difference between the two sets in all phases except during the phase of set two from the lower bilateral recti when compared to the EM. No critical value was obtained when comparing the third set by the two-tailed t-test and ANOVA-RM