Biomechanics of sit-up exercises.

Sit-up exercises performed by four male subjects revealed the presence of initial lumbar "hollowing" (lumbar curvature), or trunk hyperextension, or both prior to trunk flexion. Maximum muscular moment developed at the hip joint, which varied with sit-up exercise, was of moderate order of magnitude. Intraesophageal pressure, cardiopulmonary response, and metabolic response to a commonly used sit-up exercise (curl-up) reveals it to be a light exercise which stresses the muscles of the lower limbs as well as those of the trunk, especially the abdominal muscle group.