Major Muscles and Actions Involved
The upper rectus abdominis and internal oblique and external oblique are involved in spinal flexion. The upper rectus abdominis is not a separate group of muscles; rather, only the upper portion of the entire muscle is in action, as substantiated by EMG (electromyographic) studies. The rest of the muscle remains under tension. In this exercise your head and shoulders are lifted and move toward your hips.
Muscles in Action
The sit-up exercise is important for all athletes who throw implements with maximum force (baseball, football, javelin, shot) and for those who perform acrobatic type movements such as diving, trampolining, and gymnastics. Upper abdominal development is very important to bodybuilders because these muscles show the ripped effect. Athletes who must handle heavy loads or must stabilize their spines, need strong abdominal (and lower back) muscles to maintain firm midsections.
Important Facts to Know