Cardiovascular Fitness Across Smoking and Activity-Based Lifestyle Groups of University Students: A Cross-Sectional Study Using the Harvard Step Test

Background: Cardiorespiratory fitness is a strong predictor of cardiovascular disease risk, yet smoking and sedentary behaviour are both common among university students and their combined effect on fitness is rarely compared directly within the same cohort. Methods: In this cross-sectional observational study, 95 male university students (of 96 recruited; 21–25 years) were purposively assigned to three lifestyle groups — smoker athletes (n = 32), non-smoker athletes (n = 31), and sedentary non-smokers (n = 32) — and assessed using the Harvard Step Test. Cardiovascular efficiency (CVE) was derived from the Physical Fitness Index formula. Group distributions were non-normal and variances were unequal, so the independent-samples Kruskal–Wallis test with Dunn–Bonferroni pairwise comparisons was used. Results: An independent-samples Kruskal–Wallis test showed that CVE differed significantly across the three lifestyle groups (p < .001). Non-smoker athletes (M = 78.61, SD = 16.99) had higher CVE than smoker athletes (M = 51.41, SD = 9.91), who in turn had higher CVE than sedentary non-smokers (M = 27.06, SD = 4.38); all pairwise comparisons were significant (adjusted p < .001). Conclusion: Regular physical activity was associated with markedly higher cardiovascular efficiency even among smokers, while a sedentary lifestyle — independent of smoking status — was associated with the poorest fitness of all three groups, underscoring physical inactivity as at least as important a target as smoking cessation in university health promotion.