Patients with inflammatory back pain were shown to differ from healthy controls in genotype of the Angiotensin-converting enzyme (ACE), which regulates vasoconstriction/-dilatation. The aim of this study is to investigate whether genetic reduction of muscle perfusion might be a pathophysiological pathway of how genes influence chronic non-specific low back pain (LBP).

The following genes will be investigated:

• Insertions-/deletions-polymorphism of the angiotensin-converting enzyme (ACE-I/D gene polymorphism; 3 genotypes: ACE-II, ACE-ID, ACE-DD).
• Anti-adhesive extracellular matrix protein Tenascin-C: gene polymorphism rs2104772

The goals of this study are to investigate whether these genotypes correlate with 1) endurance of back muscles, 2) comorbidities such as asthma and diabetes and 3) the risk for LBP as assessed by a LBP-classification tool.

Inclusion Criteria:

• 18-65

Exclusion Criteria:

• Spinal surgery
• Spinal fracture
• Inflammation
• Tumour
• Severe chronic disease which make intensive physical activity impossible (osteoporosis, cardiovascular heart diseases)

Patients with chronic low back pain and healthy controls without low back pain.