The purpose of this study is to explore the cortical regulation of the paraspinal muscles in chronic low back pain. These (possible) changes in regulatory mechanisms are being compared to other motor control tests in order to determine whether correlations are found. Furthermore the patients are being treated with repetitive transcranial magnetic stimulation (rTMS) and tested afterwards. The purpose is to find out if rTMS-therapy is capable of normalizing motor control deficits.

Inclusion Criteria:

• chronic nonspecific low back pain for at least six months
• male gender
• age 25-50 yrs
• average pain during last week 4-8/10 by VAS
• Oswestry disability index 20-80 %

Exclusion Criteria:

• former spinal operations
• rheumatic disease, marked spondylolysis and -olisthesis, other diseases that markedly reduce physical or psychological performance, history of epilepsy, history of taking epileptic or strong opioid drugs