Core in 4: Rectus abdominis strain (athletic)

The core is not a single muscle but a coordinated system spanning the abdominal wall, deep spinal muscles, pelvic floor, and diaphragm. Together, these structures stabilize the trunk and pelvis, allowing force generated by the legs to transfer efficiently to the arms and back again during walking, lifting, and sport.

Unlike most regions covered on this site, the core is rarely the site of an acute traumatic injury; instead, it is more often discussed in the context of deconditioning, muscular imbalance, or its supporting role in preventing and managing low back pain. Research on core stability exercise has grown substantially since the 1990s, though its precise role relative to general strength and conditioning remains an active area of study.

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.