Core in 4: Rectus abdominis — Section 915: Rectus abdominis

This page reviews the core's anatomy, common issues related to weakness or dysfunction, how clinicians assess trunk control, and general exercise progressions used in both rehabilitation and general fitness settings. The core includes the deep transversus abdominis, the rectus and oblique abdominal muscles, the multifidus and erector spinae along the spine, the diaphragm above, and the pelvic floor below.

Is core strength the same as having visible abdominal muscles? No — core strength refers to the ability of trunk muscles to stabilize the spine under load, which is a functional quality distinct from muscle visibility, which depends more on body composition. Core strengthening is commonly included in back pain prevention programs and is associated with reduced recurrence in some studies, though it is one of several contributing factors alongside general activity and load management.

How many sit-ups should someone do for a strong core? Modern core training generally emphasizes anti-movement exercises like planks and dead bugs over high-repetition spinal flexion, since repeated sit-ups load the lumbar discs without necessarily improving functional stability. Diastasis recti is a widening of the connective tissue between the two sides of the rectus abdominis, common during and after pregnancy, that can affect trunk support and is often addressed with targeted rehabilitation exercise.