Back pain in children - No association with objectively measured level of physical activity

Study Design. A cross-sectional survey of 481 children aged 8-10 years and 325 adolescents aged 14-16 years obtained through a proportional two-stage cluster sample of children living in Odense, Denmark. Objectives. To investigate whether there are any associations between back pain and the level of self-reported physical activity, the level of self-reported physical inactivity, and the level of objectively measured physical activity. In addition, to test the validity of the self-reported physical activity data. Summary of Background Data. A sedentary lifestyle in children is believed to be harmful for the back, whereas moderate physical activities are supposed to be beneficial. There is no obvious epidemiologic evidence in favor of this concept. In none of the previous studies has the combined activity/inactivity pattern been investigated, nor has the amount of physical activity been measured objectively. Methods. The associations and dose-response connections for back pain, mid back pain, and low back pain in the preceding month were studied in relation to self-reported physical activity and physical inactivity. In addition, an objective and validated method to measure the daily level of physical activity (the accelerometer) was used to establish the associations with the same outcome variables. The association between the level of self-reported activities and the accelerometer was investigated. Results. The self-reported data resulted in mixed findings, but there were no associations between any of the three pain variables and the readings from the accelerometer, and no changes occurred after adjustment for age, gender, and puberty stage. There was a weak and inconsistent correlation (0.25) between the accelerometer readings and self-reported physical activity that nevertheless tested significantly for trend but none between the accelerometer readings and the level of self-reported physical inactivity. Conclusions. There is no obvious association between the objectively measured level of physical activity and back pain in children and adolescents. Simple self-reported levels of physical activity and inactivity cannot be used meaningfully on young people in back pain research.