Anger Expression Affects Lower Back Pain

Here's a study that correlates anger inhibition with increased severity in chronic lower back pain.

Trait Anger Management Style Moderates Effects of Actual ("State") Anger Regulation on Symptom-Specific Reactivity and Recovery Among Chronic Low Back Pain Patients

Excerpt:
Results implicate lower paraspinal muscle tension as a potential physiological mechanism that links the actual inhibition of anger following provocation to chronic pain severity among chronic low back pain (CLBP) patients. Results also highlight the importance of mismatch situations for patients who typically regulate anger by expressing it. These CLBP patients may be at particular risk for elevated pain severity if circumstances at work or home regularly dictate that they should inhibit anger expression.