The impact of e-cigarette smoking on pulmonary responses to maximal exercise

Electronic cigarettes (e-cigarettes) have emerged as popular alternatives to smoking conventional tobacco, particularly in a younger demographic. However, there is emerging and conflicting evidence on the magnitude of airway damage with e-cigarette usage. While evaluating airway health can be challenging, using a stimulus such as exercise may be used to elucidate the effects of e-cigarettes on the pulmonary system. Purpose: To determine the impact of an acute maximal exercise on changes in pulmonary function (i.e. bronchodilation and bronchoconstriction) in young adult exclusive e-cigarette smokers (S) compared to nonsmokers (NS). We hypothesized that S will have lower post-exercise bronchodilation after an acute maximal exercise compared to NS. Methods: 10 NS (3 male; 7 female; 19.8 ± 4.3 years; 67.1 ± 3.0 in; 70.7 ± 12.6 kg) and 7 S (4 male; 3 female; 21.0 ± 2.8 years; 66.3 ± 2.3 in; 65.9 ± 10.1 kg) completed an incremental test to exhaustion to determine peak oxygen consumption (VO2peak) on a cycle ergometer. Subjects performed standard pulmonary function tests to assess forced vital capacity (FVC), forced expiratory volume in 1-second (FEV1), FEV1/FVC, forced expiratory flow between 25-75% of FVC (FEF25-75%) and peak expiratory flow (PEF) before the exercise test and immediately post-exercise. Post-exercise bronchodilation and bronchoconstriction were quantified as a percent change from pre-exercise values. Results: The NS and S group were similar for age, height, weight, body composition, VO2peak, peak power, and peak heart rate (all p’s \u3e 0.05). There was a trend towards significance for FEV1/FVC (0.8 ± 9.0% versus -6.3 ± 7.5%, p = 0.081, Cohen’s d= 0.89) and FEF25-75% (3.7 ± 17.8% versus -11.8 ± 18.9%, p = 0.082, Cohen’s d= 0.86) from pre- to post-exercise for the NS and S group respectively. Conclusion: E-cigarette usage may be impacting the airways despite normal resting pulmonary function in S, however decreases in pulmonary function after maximal exercise in S compared to NS