The diaphragm has two distinct functions that are often discussed in isolation but operate simultaneously. As a respiratory muscle, it drives the inhalation-exhalation cycle by changing intrathoracic pressure. As a postural stabiliser, it contributes to intra-abdominal pressure and to the stabilisation of the lumbar spine as part of the deep core system. When breathing mechanics become dysfunctional, both functions are compromised, and the postural compensation patterns that develop are a direct contributor to chronic spinal pain.
Dysfunctional Breathing Patterns
Thoracic breathing, also called chest breathing or accessory muscle breathing, occurs when the diaphragm does not descend adequately during inhalation and the thoracic cage and upper shoulders lift instead. This pattern is common in adults with chronic stress, forward head posture, and thoracic kyphosis. It maintains the thoracic cage in a relatively elevated position, reduces rib cage mobility, compresses the thoracic facet joints, and over-activates the scalene and sternocleidomastoid muscles of the neck, contributing to chronic neck pain and headache.
The Diaphragm and Lumbar Stabilisation
Research from the Australian group led by Paul Hodges has documented the timing of diaphragm contraction relative to limb movement. In healthy adults, the diaphragm co-contracts with the transversus abdominis before any upper or lower limb movement, pre-stiffening the lumbar spine in anticipation of load. In adults with chronic lower back pain, this anticipatory co-contraction is delayed or absent, meaning the lumbar spine moves without adequate prior stabilisation. Restoring normal diaphragmatic breathing mechanics is therefore a prerequisite for effective lower back rehabilitation.
Sources
- Hodges, P.W., & Gandevia, S.C. (2000). Changes in intra-abdominal pressure during postural and respiratory activation of the human diaphragm. Journal of Applied Physiology, 89(3), 967-976.
- Perri, M.A., & Halford, E. (2004). Pain and faulty breathing: a pilot study. Journal of Bodywork and Movement Therapies, 8(4), 297-306.
- Lee, L.J., & Hodges, P.W. (2015). Behavior of the diaphragm during arm raises in subjects with and without low back pain. Journal of Orthopaedic and Sports Physical Therapy, 45(9), 652-662.