Research on the relationship between mental health and physical health of college students: a retrospective cohort study

Abstract Background This study aims to examine the prospective associations between college students’ baseline psychological symptoms and their subsequent physical fitness outcomes to provide a scientific basis and practical reference for the formulation of mental health education in colleges and universities and strategies for promoting their physical fitness. Methods This retrospective cohort study with longitudinal physical fitness follow-up selected 6,491 undergraduate graduates from six consecutive admission cohorts (2019–2024) at a comprehensive university as the research subjects. The Symptom Checklist-90 (SCL-90) was used to assess their psychological symptoms, and their physical fitness test scores were incorporated into the analysis. Correlation analysis, group comparisons, and linear mixed-effects models were employed to examine the associations between psychological symptoms and physical fitness test results. Results There were significant differences in the scores of obsessive-compulsive, depressive, anxious, and phobic factors on the SCL-90 between male and female college students, with female students scoring higher than male students, although all differences were small in magnitude (Cohen’s d < 0.25). Students with higher first-year physical fitness test scores tended to have lower SCL-90 factor scores than those in the lower-score group did, but the differences were very small (ε² ≤ 0.001) and only paranoid ideation and additional items remained significant after Bonferroni correction. Weak negative correlations were observed between most psychological symptom factors and both physical fitness outcomes. After Bonferroni correction, six of the ten SCL-90 factors remained significantly negatively correlated with the comprehensive physical fitness GPA. Linear mixed-effects models showed that physical fitness test scores declined significantly across the four academic years (B = -0.888 per year, P < 0.001), whereas baseline psychological symptom severity was not significantly associated with either the level or the rate of change of fitness scores. Conclusions Baseline psychological symptoms showed weak and largely non-significant prospective associations with subsequent physical fitness outcomes; cross-sectional associations were more evident for the comprehensive physical fitness GPA than for first-year fitness scores, and baseline symptom severity was not significantly associated with the four-year fitness trajectory.