Inclusion Criteria:  acute low back pain (< 6 weeks) with or without radiating pain aged 18 to 60 years a pain-free episode for at least 3 months before the onset of their current back pain read and understand the Dutch language.  Exclusion Criteria:  previous lumbar spinal surgery lumbar radicular syndrome specific cause of low back pain lumbar spinal stenosis current malignancy spondyloarthropathy osteoporosis spondylolisthesis major trauma infection systemic disease.