Studies show that the cumulative prevalence of low back pain (LBP) in juveniles was close to 30%. The majority of the LBP was mild. Of those with LBP approximately 8% sought medical treatment. Chronic or recurrent LBP averaged 8.1% of the adolescent populations studied. The cumulative prevalence of LBP increased with age. One study showed a cumulative prevalence of LBP of over 70% by age 15. A potential link between the adolescent growth spurt and the increased prevalence of LBP was proposed. Asynchronous bone growth resulting in skeletal malalignment was proposed as a possible cause of LBP. Immaturity of the vertebral bony structures was thought to increase the risk of pars defects. Correlations between anthropometric measurements of height and weight were inconclusive. The role of decreased muscle flexibility in LBP was also inconclusive. Some researchers found a correlation between age, gender, height and LBP. Disc degeneration and spondylolytic symptoms were also noted as sources of LBP. However, not all cases of disc degeneration (DD) or spondylolysis were symptomatic of LBP. It was noted that the prevalence of DD was rare in adolescents. Disc protrusions were more common in LBP groups than in non-LBP groups, and females with LBP had more disc protrusions than males with LBP. Risk factors for spondylolysis and spondylolisthesis included genetics, the growth spurt, repetitive stresses and sports participation. Within competitive sports, age and training more than 15 hours/week correlated with the incidence of spondylolytic changes. Participation in sports as a risk factor for LBP was reported. A familial tendency for LBP was noted in one study in which the child had an increased incidence of reported LBP if one or both parents had a history of LBP.