The Core Is Not Just Abdominal and Back Muscles: The Role of the Diaphragm in Core Stability

Trunk stabilization, also referred to as core stability (CS) has been defined as the internal platform of support of the trunk and limbs, against internal and external forces acting on the body. Core stability has been recognized as being a subset of ‘Motor Control’, however, the way it is being taught and applied by individuals is at times in conflict with motor learning and motor control principles. Early evidence supporting poor neuromuscular control patterns in the trunk muscles, transverse abdominis in particular, in low back pain subjects, were perhaps taken out of context in CS training, leading to the assumption that these are the key CS muscles needing attention for trunk stabilization, aiming at core strengthening rather than neuromuscular control and conditioning.

Evidence today addresses trunk stabilization together with postural trunk control, recognizing the role of general movement and intrinsic postural control, both needed for the stability of the key platform of support, the pelvis, as well as the trunk and limbs prior to any movement. The diaphragm is a key player linking between the trunk and the pelvis, contributing to their support and to the postural control mechanism, having an anatomical and biomechanical relationship with trunk stabilizers (abdominals, multifidi, pelvic floor), and a functional relationship contributing to and modifying the intra-abdominal pressure (IAP), another important element in trunk stabilization. This is in addition to its role in breathing and ventilation.

Adequate control of the diaphragm is a pre-requisite for initiation and coordination between the transverse abdominis, pelvic floor and multifidi muscles as main contributors to core stability. This is why optimizing breathing and diaphragm control is suggested as part of any treatment goals for posture, movement, muscle activation and core conditioning.

This presentation will examine the various relationships of the diaphragm with trunk stabilizers (anatomical, biomechanical and functional), and its role in the formation and adaptation of IAP for trunk stability, as the basis for movement and posture, considering it being perhaps the real ‘Core’.