An electromyographic study of four abdominal exercises

This study was designed to determine the intensity and duration of EMG muscle action potentials in the upper and lower segments of the rectus abdominis (RA) muscle during four abdominal exercises: the conventional sit-up, the hook sit-up, the arched back sit-up, and the double leg raise. Integrated muscle action potentials were analyzed for both intensity (maximum pen deflection) and duration (amount of time during the contraction in which a moderate degree of activity was present). All three types of sit-ups elicited significantly greater intensity of contraction than the leg lift exercise in both the upper and lower RA. The three sit-up exercises did not differ significantly from each other. Since the intensity of the leg lift exercise was seldom sufficient to allow a duration measurement to be taken, only the three sit-up exercise were included in the analysis of duration. In duration the arched back sit-up significantly surpassed the hook and conventional sit-up for both the upper and lower rectus muscle. The hook and conventional sit-up did not differ significantly from each other. In every subject, for both intensity and duration, the readings were much higher in the upper rectus than in the lower rectus.