Sustained Abdominal Exercises Affect Abdominal Muscle Activation and Maximal Expiratory Pressures Differently in Healthy Men and Women

Purpose: To compare the effects of sustained abdominal exercises—pelvic tilt and twist curl-up—on the magnitude of abdominal muscle activation and maximal expiratory pressure (MEP) in healthy men and women. It was hypothesized that the activation would differ between men and women during these 3 exercise maneuvers. Methods: Using a cross-sectional design, 10 healthy men and 10 women sustained pelvic tilt and twist curl-up exercises until task failure. Baseline MEP was compared with MEP immediately after both exercises. The root mean square of the internal oblique, rectus abdominis, external oblique, and transverse abdominis were evaluated during pelvic tilt, twist curl-up, and MEP. Results: Pelvic tilt and twist curl-up were sustained for similar durations. Twist curl-up induced higher activations and more shifts to lower median frequency in all 4 abdominals compared with pelvic tilt. Although internal oblique activation was highest during MEP and lowest during pelvic tilt in women, these comparisons did not differ in men. Maximal expiratory pressure tended to decrease after sustained pelvic tilt in women but did not change in men. Conclusions: Twist curl-up activated abdominal muscles more so than pelvic tilt. Some sex differences were shown that should be considered in future research of abdominal muscle exercise prescription.