Role of Transverse Abdominal Muscle in Trunk Stability

Mechanical stability of the lumbar spine is known to have implications for injury and chronic low back pain. Even though this topic is fairly covered by scientific literature, the role of abdominal muscles, in particular the deep once, is often neglected. Especially transverse abdominal (TA) muscle might play privileged role: with mainly transverse muscular fibers, both activated TA muscles compress abdominal cavity generating increase in intra-abdominal pressure (IAP) without exerting any moment on the spine and trunk. It is hypothesized that TA muscles may significantly contribute to lumbar spine stability through increased IAP acting on lumbar lordosis. They may also act through traction in thoraco-lumbar fascia resulting in compressive forces applied to lumbar spine. In contrast to the other abdominal muscles, TA activation seems independent of the direction of the imposed loading. Next paragraphs attempt to provide deeper insight in TA privileged role in spine stability and IAP control.