Flexibility and muscle strength/resistance indicators and screening of low back pain in adolescents

Abstract

Low back pain is increasing considerably among adolescents, reaching proportions similar to the adult population. Flexibility (Flex) and muscle strength/resistance, components of Health-Related Physical Fitness (HRPF), seem to be associated with presence of low back pain. The aim of this study was to assess the ability of Flex and muscle strength/resistance in the screening of adolescents with low back pain and to propose cutoff points for these HRPF components. The study was conducted with 1.455 students aged 10-17 years randomly selected. Low back pain was estimated using a questionnaire. Flex was measured by the sit and reach test and muscle strength/resistance by the one minute sit up test. The analysis of the receiver operating characteristic (ROC) curve was used to identify the capacity of Flex and muscle strength/resistance for screening low back pain. To propose cutoffs points, the best balance between sensitivity and specificity was analyzed. The frequency of low back pain was 16.1 %, higher (p<0.05) among females (21.6%) than in males (10.5%). The ROC curve analysis indicated that Flex is able to identify girls more likely of having low back pain (p<0.05). Sit and reach test and the proposed cutoff points can be used as screening tool of female adolescents more likely of having low back pain.