Passive lumbar mobility. A prospective study of back pain in young men during their military service.

Mobility of the back is mostly evaluated through active mobility in a standing position. In this study, also the passive mobility between lumbar vertebraes was assessed in sidelying, and grouped in four categories. More than five hundred young men were examined three times over a period of 3-4 years, before and after their basic military training. The lumbar vertebra L5 was judged to have decreased mobility in 29% and increased mobility in 17% of the cases. The corresponding values for L4 were 39% and 13%, respectively. There were significant positive correlations between the results of all the examinations. The total agreement between examinations was around 50%. Decreased passive lumbar mobility correlated to the current amount of back discomfort at the second and third examinations, but at the first examination it could not predict the future incidence of back pain.