Tightness of hamstring- and psoas major muscles. A prospective study of back pain in young men during their military service.

Muscular tightness and the therapeutic effect of stretching has been widely discussed during the last few years in sports training and physiotherapy. Within a prospective study of back function and pain before and after compulsory military service, tightness of hamstring- and psoas muscles was assessed. Around 600 young men were examined three times over a period of four years. Tight hamstring muscles were found to be very common in this group. Only 43% of the right and 35% of the left legs reached an angle of at least 80 degrees from the couch during the straight-leg-raising test (Lasegue's test). The test of muscular tightness showed a significant test-retest reliability over all examinations. Tight hamstring- or psoas muscles could not be shown to correlate to current back pain or to the incidence of back pain during the follow-up period.