What action does the rectus abdominis muscle perform?

The rectus abdominis muscle is primarily responsible for the flexion of the spine. This muscle runs vertically along the front of the abdomen and plays a crucial role in movements that involve bending forward, such as during sit-ups or trunk curls. When the rectus abdominis contracts, it pulls the rib cage closer to the pelvis, thereby flexing the lumbar spine.

Understanding the function of this muscle is important for activities that require core engagement and stability. For example, during exercises designed to strengthen the core, knowing that the rectus abdominis facilitates spinal flexion helps in executing the movements correctly and safely. This muscle also aids in maintaining good posture and provides support during various physical activities, making it integral to overall functional fitness.