Physical exercise, sports, and lung function in smoking versus nonsmoking adolescents

Associations between adolescent smoking habits and exercise, particularly participation in sports and lung function were studied. All students aged 13-19 yrs in Nord-Trøndelag County, Norway, 1995-1997, were invited to join a cross-sectional study. Information on smoking habits and exercise was obtained by self-administered questionnaire. Spirometry was performed in accordance with American Thoracic Society standards. Of the 6,811 students (aged 13-18 yrs, without asthma), 2,993 (44%) reported never-smoking, and 1,342 (20%) reported current smoking (90% daily). Frequency of physical exercise was inversely associated with smoking, but participants in individual sports with lesser endurance, especially body-building and fighting sports, were more likely to be daily smokers than nonparticipants. Both daily (53%) and occasional smokers (43%) were more likely to have quit sports than never-smokers (26%)). Never-smokers showed a positive dose-response between physical exercise and lung function (forced vital capacity and forced expiratory volume in one second, adjusted for age and height). No similar significant association was observed in daily smokers. These data suggest that smoking habits in different sports should be considered when promoting physical activity as smoking prevention, and sports organizations should include smoking prevention programmes. Adolescents with better lung function may self-select into sports; this possibility needs to be studied in a longitudinal design.