Accelerometer-based sedentary time and physical activity with incident and progressive tobacco smoking in 2503 children: A 13-year mediation and temporal longitudinal study

Background: Long-term accelerometer-based studies examining whether engaging in physical activity (PA) reduces the risk of smoking in children are lacking, and whether directly measured adiposity increases smoking risk is uncertain. Methods: From the Avon Longitudinal Study of Parents and Children (ALSPAC), UK birth cohort, 2503 children aged 11 years with complete smoking and at least one valid time-point movement behaviour data were followed up until age 24 years. ActiGraph assessed sedentary time (ST), light PA (LPA), and moderate-to-vigorous PA (MVPA) at ages 11, 15, and 24-year clinic visits and smoking-based questionnaires were administered, whilst fat mass was measured with dual-energy x-ray absorptiometry scanner. Data were analysed with generalized linear-mixed effect models with logit-links and structural equation models. Results: Mean [SD] age at baseline was 11.71 [0.20] years and the prevalence of smoking at ages 13, 15, and 24 years were 1.5%, 13.5%, and 26.6%, respectively. Higher MVPA at age 11 years was significantly associated with lower odds of smoking at age 13 years (odds ratio, 0.991; [95% CI, 0.983-0.999], P = 0.035). Cumulative MVPA during ages 11-24 years was significantly associated with lower odds of progressive smoking during growth from ages 13-24 years (0.992; [95% CI, 0.989-0.996], P < 0.001). Cumulative ST and LPA had no significant associations with smoking. Higher fat mass suppressed (10% suppression) the inverse relationship between MVPA and smoking. In path analysis, higher MVPA at age 15 years temporally preceded reduced smoking at age 24 years. Conclusion: In the present study, engaging in MVPA from age 11 years may prevent 9 in 1000 children from starting smoking at the age of 13 years when smoking prevalence was 15 in 1000 children, i.e potentially preventing 60% of children from initiating smoking. However, the MVPA preventive approach diminished as children grew into young adults.