Association between long-term smoking and leisure-time physical inactivity: a cohort study among Finnish twins with a 35-year follow-up.

OBJECTIVES

To investigate longitudinal associations of smoking and a change in smoking status with leisure-time physical inactivity. In addition, to control whether familial confounding (genetics and shared environment) influences the associations.

METHODS

Data were based on the population-based Finnish Adult Twin Cohort of 5254 twin individuals born in 1945-1957 (41% men) and who participated in all four surveys over a 35-year follow-up (1975-2011). Logistic and conditional logistic regression models with multiple covariates were used for analyses.

RESULTS

Compared to never-smokers, long-term daily smokers (1975-1990) had the highest likelihood for both long-term inactivity and to change into inactive by 2011. Recurrent smoking was associated with long-term inactivity. Instead, in comparison to persistent daily smokers, quitting smoking decreased the likelihood of becoming physically inactive at leisure time. The associations remained in the analyses which accounted for multiple covariates and/or familial confounding.

CONCLUSIONS

Daily smoking increases the likelihood of remaining or becoming physically inactive over the decades. Our results emphasize not only the importance of preventing smoking initiation, but also to support early smoking cessation in promotion of lifelong physical activity.