Associations of moderate-to-vigorous physical activity and body roundness index with psychological symptoms in adolescents in mainland China: a national multicenter cross-sectional survey

Background: Decreased physical activity and overnutrition among adolescents have become important public health problems shared by countries around the world. In addition, the prevalence of psychological symptoms among adolescents continues to increase, which negatively affects schooling and future quality of life. However, no studies have been found in the past on the association of moderate-to-vigorous physical activity(MVPA) and body roundness index(BRI) with psychological symptoms in Chinese adolescents. This study may provide theoretical support for the prevention and intervention of psychological symptoms among adolescents in mainland China. Methods: From September to November 2023, MVPA, BRI, and psychological symptoms were assessed in 43,031 adolescents aged 12–17 years from different regions of mainland China. The chi-square test, t-test, logistic regression analysis, and ordered logistic regression were used to analyze the associations that existed between MVPA and BRI with psychological symptoms. Results: The prevalence of psychological symptoms among adolescents in mainland China was 20.3%. The proportions of adolescents with MVPA of < 30 min/day, 30–60 min/day, and > 60 min/day were 46.0%, 40.0%, and 14.0%, respectively. The adolescent BRI value was (2.02 ± 0.95); boys (2.12 ± 1.03) had a higher BRI value than girls (1.92 ± 0.86), and the difference was statistically significant (t = 22.111, P < 0.001). After adjusting for relevant covariates, ordered logistic regression analysis showed that, overall, adolescents in the group with MVPA > 60 min/day and BRI quartiles Q1 as the reference group, adolescents in the group with MVPA of 30–60 min/day and BRI quartiles Q2 (OR = 0.65, 95% CI:0.51 ∼ 0.82) had a lower risk of developing psychological symptoms (P < 0.001); adolescents in the MVPA < 30 min/day group and BRI quartiles Q4 group (OR = 1.62, 95% CI: 1.30–2.02) had a higher risk of psychological symptoms (P < 0.001). Conclusions: There is an association between MVPA and BRI and psychological symptoms among adolescents in mainland China. A decrease in MVPA and an increase in BRI were associated with an increase in the prevalence of psychological symptoms. In the future, we should effectively improve the MVPA level and maintain a reasonable BRI value in adolescents in mainland China to better promote adolescents’ mental health development. Clinical trial number: Not applicable.