"Physical exercise, sports, and lung function in smoking versus nonsmoking adolescents”. T.L. Holmen, E. Barrett-Connor, J. Clausen, J. Holmen, L. Bjermer. Eur Respir J 2002; 19: 8–15.

Effects of physical exercise on lung function in never-smoking and daily-smoking adolescents, aged 13–18 yrs, attending both questionnaire and spirometry in the Young-Hunt study. a, c) Males, never-smokers (exercise: ≤1 day·week⁻¹, n=349; 2–3 days·week⁻¹, n=593; ≥4 days·week⁻¹, n=570); b, d) females, never-smokers (exercise: ≤1 day·week⁻¹, n=445; 2–3 days·week⁻¹, n=671; ≥4 days·week⁻¹, n=344); e, g) males, daily smokers (exercise: ≤1 day·week⁻¹, n=171; 2–3 days·week⁻¹, n=99; ≥4 days·week⁻¹, n=47); f, h) females, daily smokers (exercise: ≤1 day·week⁻¹, n=219; 2–3 days·week⁻¹, n=96; ≥4 days·week⁻¹, n=39). Students who reported ever having asthma were excluded. Per cent differences and 95% confidence intervals for differences were calculated on a logarithmic scale using those who had the lowest level of exercise (≤1 day·week⁻¹) as a reference, and adjusting for age, height, weight, passive smoking at home, rhinitis and acute bronchitis with cough. FVC: forced vital capacity; FEV₁: forced expiratory volume in one second.