Abstract
BACKGROUND: Substance use and physical inactivity in youths could influence brain development, academic performance, and long-term physical and mental health outcomes. Therefore, this study examined the associations between substance use and weekly days of moderate to vigorous physical activity (MVPA) among children and adolescents. METHODS: Data were drawn from the Health Behavior in School-Aged Children (HBSC) cross-sectional study (2013–2019), comprising 358,391 children and adolescents (51% girls) from 45 countries (aged 10–17 years). Generalized linear mixed models with a Poisson distribution were fitted and mutually adjusted for age, sex, socioeconomic status, body mass index status, and survey year, to estimate the average predicted means of weekly days with at least 60 min of MVPA in relation to substance use (alcohol, tobacco, and cannabis) in non-users versus users and among frequency levels in the last 30 days. RESULTS: Alcohol and cannabis non-users versus users did not differ significantly in physical activity levels. In contrast, children and adolescents who reported tobacco use co-occurred with lower levels of MVPA with a significant mean difference (MD) of 1.09 days/week (95% CI [confidence interval] 1.06 to 1.11; p < 0.001) compared to non-users. In terms of substance use frequency levels, alcohol use showed a positive association between MVPA, especially among participants who drunk ≥ 30 days in relation with low to moderate alcohol users (0–5 days) (all p < 0.05). Across tobacco users, lower levels of physical activity were observed in relation with higher frequency of use (all p < 0.001 compared to non-users), particularly among frequent users. The largest difference was reported between tobacco non-users and those with 20 to 29 days of use (MD = 1.13; 95% CI 1.07 to 1.20; p < 0.001). Cannabis use exhibited a nonlinear trend, with no statistically significant differences across use frequencies. Gender analysis showed that boys had higher levels of physical activity and different substance use patterns compared to girls. Tobacco use was associated with a stronger reduction in MVPA among girls (p < 0.001), while alcohol showed no significant associations (all p > 0.05) and cannabis was linked to slightly higher MVPA only in boys (p = 0.035). CONCLUSION: Among the recreational substances examined, both dichotomous and ordinal analyses showed that tobacco use was consistently associated with lower levels of physical activity among children and adolescents. Notably, these associations varied by sex, with boys reporting higher MVPA overall and the negative impact of tobacco use being more pronounced among girls. However, the direction of this relationship remains unclear, underscoring the need for experimental research. These findings support integrated public health strategies that combine substance use prevention with the promotion of physical activity. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12889-025-25448-4.