Intervertebral disc changes after 1 h of running: a study on athletes.

The lumbar spines of 25 long-distance runners were examined using an upright magnetic resonance imaging scanner. All volunteer runners were scanned before and after running for 1 h. Scanning was performed with the runners seated upright (neutral), leaning forwards (flexion) and leaning backwards (extension). All measured discs showed a reduction in disc height after 1 h of running. A significant reduction in disc height was observed in all three body positions (neutral, flexion and extension) after 1 h of running. The results showed that, in flexion, extension and neutral positions, intervertebral discs undergo significant strain after 1 h of running. The lowest disc-height reduction was found at the L5 - S1 space in the neutral position; the same space had the highest percentage of disc degeneration.