Childhood physical activity can prevent tobacco smoking in adolescence

Teenagers may be less likely to initiate tobacco smoking if they engage in moderate-to-vigorous physical activity (MVPA) from childhood, a new study conducted in collaboration between the Universities of Bristol and Exeter in the UK, and the University of Eastern Finland shows. The results were published in the Journal of Behaviour Research and Therapy.

Childhood and teenage tobacco smoking is a strong preventable risk factor for premature structural and functional cardiac damage already in the mid-twenties. Physical activity intervention studies have reported reduced smoking rates among adults; however, physical activity studies in preventing smoking in children and adolescents have been inconclusive due to short study durations, small population sizes, and lack of accelerometer-measured physical activity data.

The present study is the largest and the longest follow-up of accelerometer-based MVPA and smoking behavior in the young population in the world. 2,503 children drawn from the University of Bristol's Children of the 90s cohort were followed up from age 11 until 24 years. The prevalence of smoking at ages 13, 15, and 24 years was 1.5%, 13.5%, and 26.6%, respectively.

At baseline, the children spent six hours per day sedentary, six hours per day engaging in light physical activity, and approximately 55 minutes per day in MVPA. At follow-up in young adulthood, nine hours per day were spent sedentary, three hours per day in light physical activity, and approximately 50 minutes per day in MVPA. The children's fasting blood samples were also repeatedly measured for low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglyceride, glucose, insulin, and high-sensitivity C-reactive protein. Blood pressure, heart rate, socio-economic status, family history of cardiovascular disease, as well as dual-energy X-ray absorptiometry measured fat mass and lean mass were accounted for in the analyses.

According to the study, 6 of 1000 children who engaged in MVPA at age 11 had initiated tobacco smoking by age 13, while the prevalence of smoking in the whole age group was 15 out of 1000. In other words, the risk of initiating tobacco smoking may be prevented in 60% of 13-year-olds who would have taken their first tobacco puff, because of childhood participation in MVPA.

Later in the follow-up, a more modest preventive effect was observed. Continuous exposure to MVPA from childhood through young adulthood could prevent smoking in 8 out of 1000 young adults, when the prevalence of smoking was 266 out of 1000 young adults.

In addition, teenagers who were non-smokers at ages 13 and 15 years spent 15 more minutes per day in MVPA by age 24 years when compared with those who had a history of smoking at ages 13 and 15 years.

Childhood sedentariness was not prospectively associated with the risk of initiating and persistently smoking tobacco.

The MVPA-smoking preventive potential had a strong causal consistency across all tested statistical models but the effect diminished by young adulthood. It's all the more important that legislation protects young people against tobacco smoking and nicotine use initiation."

Andrew Agbaje, physician and associate professor (docent) of Clinical Epidemiology and Child Health, University of Eastern Finland

"Stopping smoking in adulthood is good but late since a residual long-term risk of heart disease for the next thirty years still exists. Thus preventing childhood smoking initiation is critical to lifelong health and these findings may be extrapolated to vaping and electronic cigarette use in teenagers since the same active ingredient in both smoke and smokeless tobacco is nicotine," Agbaje concludes.

Agbaje's research is supported by research grants from Jenny and Antti Wihuri Foundation, the Finnish Cultural Foundation Central Fund, the Finnish Cultural Foundation North Savo Regional Fund, the Orion Research Foundation, the Aarne Koskelo Foundation, the Antti and Tyyne Soininen Foundation, the Paulo Foundation, the Yrjö Jahnsson Foundation, the Paavo Nurmi Foundation, the Finnish Foundation for Cardiovascular Research, Ida Montin Foundation, Eino Räsänen Fund, Matti and Vappu Maukonen Fund, Foundation for Pediatric Research, Alfred Kordelin Foundation and Novo Nordisk Foundation.