Bidirectional associations between pain and physical activity in adolescents

Objectives: The objectives were to: (1) examine temporal relationships between pain and activity in youth, specifically, whether physical activity affects pain intensity and whether intensity of pain affects subsequent physical activity levels on a daily basis, and (2) examine clinical predictors of this relationship. Methods: Participants were 119 adolescents (59 with chronic pain and 60 healthy) aged 12 to 18 years, 71% female. Adolescents completed 10 days of actigraphic monitoring of physical activity and daily electronic diary recordings of pain intensity, medication use, sleep quality, and mood. Linear mixed models assessed daily associations among physical activity and pain. Daily mean (average count/min) and peak (highest daily level) activity were used for analyses. Medication use, sleep quality, and mood ratings were included as covariates, and age, sex, and body mass index percentile were adjusted for. RESULTS: Higher pain intensity was associated with lower peak physical activity levels on the next day (t641=-2.25, P=0.03) and greater medication use predicted lower mean physical activity levels the same day (t641=-2.10, P=0.04). Higher mean physical activity levels predicted lower pain intensity ratings at the end of the day (t705=-2.92, P=0.004), but only in adolescents with chronic pain. Discussion: Youth experiencing high pain intensity limit their physical activity level on a day-to-day basis. Activity was related to subsequent pain intensity, and may represent an important focus in chronic pain treatment. Further study of the effect of medications on subsequent activity is needed.