Sit-ups have been the cornerstone of fitness programs for years. Google
The main purpose of sit-ups is to strengthen the "stomach" muscles by challenging the abdominal group: the rectus abdominus muscles, or "abs" (two thin strips of muscle that extend from the breastbone to the pelvis), and the three layers of muscles that flank the abs. Google
Great care and excellent technique are required to strengthen the abdominal muscles with sit-ups. Google