Cardiorespiratory fitness and depressive symptoms in female university students: an adiposity-independent association in a cross-sectional study

Depression is among the leading causes of disability in young adults, with a consistently higher burden in females and in university populations. Although higher cardiorespiratory fitness (CRF) has been inversely associated with depressive symptoms, its interplay with adiposity in this population remains poorly characterised. We hypothesised that higher CRF would be associated with fewer depressive symptoms across adiposity strata, and that the joint presence of low CRF and elevated adiposity would identify the subgroup at greatest likelihood of clinically relevant depressive symptomatology. In a cross-sectional sample of 251 female undergraduate students (mean age 20.63±2.90 years), depressive symptoms were assessed using the Center for Epidemiological Studies Depression Scale–10 (CES-D-10; cut-off ≥10). Adiposity was quantified by dual-energy X-ray absorptiometry (DXA; %body fat) and CRF by symptom-limited cardiopulmonary exercise testing (CPET; VO 2 peak). Participants were classified into four mutually exclusive groups—Unfatness–Fit, Unfatness–Unfit, Fatness–Fit, and Fatness–Unfit—using previously validated population-based cut-off points consistent with ACSM normative data and the fat-but-fit classification framework (body fat≥32%; VO 2 peak≥35 mL·kg -1 ·min -1 ). Analysis of covariance (ANCOVA), robust Poisson regression, and logistic regression were used to examine group differences in CES-D-10 scores and the odds and prevalence of clinically relevant depressive symptomatology, adjusting for academic year of enrolment, smoking, physical activity, screen time, and diet quality. Thirty percent of participants met the CES-D-10 threshold for clinically relevant depressive symptomatology. VO 2 peak correlated inversely with CES-D-10 scores (Spearman's ρ=−0.19, p<0.01). Adjusted CES-D-10 scores differed significantly by adiposity–fitness group (F[3, 135]=2.736, p=0.047; partial η 2 =0.046). The Fatness–Unfit group had higher adjusted CES-D-10 scores than the Unfatness–Fit group (adjusted mean difference=−2.68 points; 95%CI: −4.66 to −0.70; Cohen's d=0.57). In logistic regression, the Fatness–Unfit group showed greater odds of clinically relevant depressive symptomatology compared with the Unfatness–Fit reference group (OR=2.12; 95% CI: 1.02–4.40). Robust Poisson regression confirmed a higher prevalence of depressive symptoms in the Fatness–Unfit group (prevalence ratio [PR]=1.70; 95% CI: 1.04–2.89). The Fatness–Fit and Unfatness–Unfit groups did not differ significantly from the reference in either model. In female undergraduate students, the combination of elevated adiposity and low CRF was associated with the highest likelihood of clinically relevant depressive symptomatology, rather than either factor independently. Higher CRF was associated with fewer depressive symptoms across adiposity strata, suggesting that adequate CRF may attenuate the adverse mental health correlates of excess adiposity. Students with elevated adiposity and low CRF constitute the highest-risk subgroup for clinically relevant depressive symptomatology. Fitness promotion may be a feasible, non-pharmacological strategy to support mental health in female university students. • Higher cardiorespiratory fitness (CRF) is associated with fewer depressive symptoms, regardless of adiposity. • Female students with high adiposity and low CRF show the greatest risk of depression. • Promoting fitness may serve as an effective non-pharmacological strategy to improve mental health in university women.