Effect of two sitting postures on lumbar sagittal alignment and intervertebral discs in runners.

Purpose: We evaluated in vivo changes in lumbar lordosis and intervertebral discs in runners and assessed the relationship between these changes and degenerative disc disease in runners with and without a history of low back pain.

Materials And Methods: Using open upright magnetic resonance (MR) imaging, we prospectively studied changes in lumbar lordosis and intervertebral discs of 25 elite long-distance runners in two sitting postures (neutral and extended) before and after 1 h of running and compared the results with disc height and dehydration/degeneration. Seventeen of the 25 runners had a history of low back pain.

Results: After 1 h of running, mean lordosis in neutral posture reduced by 4°; reduction was significant in runners with a history of low back pain. A significant reduction in mean lordosis in extension was not observed. Mean disc height significantly reduced in both postures, without, however, any statistical significance between runners with and without a history low back pain in any posture. Variable degrees of disc dehydration/degeneration were observed in 23 runners (57 discs), more commonly at L5-S1. A significant difference of disc dehydration/degeneration between runners with and without a history of low back pain was not observed.

Conclusions: Intervertebral discs undergo significant strain after 1 h of running that in the long term may lead to low back pain and degenerative disc disease. Runners, especially those with low back pain and degenerative disc disease, should be evaluated after training to preserve the normal lumbar lordosis.