Background: E-cigarette use among university students has been increasing. While substantial information exists on the impact of e-cigarette use on respiratory function, limited data exists on its early effects on cardiac autonomic function and exercise capacity in young individuals.

Aims: This study evaluated respiratory function, heart rate variability (HRV), and exercise capacity in electronic cigarette users compared to traditional cigarette smokers and non-smokers among university students.

Methods: Sixty-one healthy volunteers aged 18-35 years were divided into three groups: nonsmokers (n=20), tobacco smokers (n=21), and e-cigarette users (n=20). Respiratory function was assessed using spirometry, HRV was measured using a Polar H10 chest strap, and exercise capacity was evaluated using the incremental shuttle walk test (ISWT).

Results: Results showed forced vital capacity was significantly higher in non-smokers than in traditional cigarette and e-cigarette users (P =0.013). No significant differences were found in spirometry parameters, HRV indices, total shuttle number, or ISWT distance. The percentage of predicted distance was significantly higher in non-smokers than other groups (p=0.018). The percentage of maximal heart rate and post-test heart rate differed significantly between groups (p = 0.004; η² = 0.172 and η² = 0.174), with traditional cigarette smokers showing lower values than non-smokers and e-cigarette users. Post-exercise dyspnea scores were significantly lower in e-cigarette users than nonsmokers (p=0.009).

Conclusion: Both tobacco and e-cigarette use may negatively affect respiratory function and exercise performance of university students. Further research is needed to clarify the long-term health effects of electronic cigarette use in both healthy and chronic disease populations.