Structural Relationships Among Physical Activity, Sleep, and Resilience: A Multi-Group Structural Equation Modeling (SEM) Study Among Physically Weak College Students

Background: Resilience is a critical psychological resource for university students to cope with stress and maintain mental health; however, students with physical weaknesses may be at greater risk due to physiological limitations. This study aimed to use multi-group structural equation modeling (SEM) to examine the associations among physical activity (PA), sleep quality, and resilience. Methods: A cross-sectional study was conducted using stratified cluster sampling among 2040 students from four universities in Beijing. The participants had a mean age of 19.03 ± 0.94 years and included 1144 men (56.1%) and 896 women (43.9%). Participants were categorized into the General Sample (n = 1504, 73.7%), Fitness-Remediation Sample (n = 341, 16.7%), and Rehabilitation Sample (n = 195, 9.6%). PA, sleep quality, and resilience were assessed using the International Physical Activity Questionnaire—Short Form (IPAQ-SF), Pittsburgh Sleep Quality Index (PSQI), and Connor–Davidson Resilience Scale (CD-RISC), respectively. Multi-group SEM was used to estimate direct and indirect associations and to compare structural paths across groups. Results: In the total sample, PA was positively associated with resilience and negatively associated with poorer sleep quality. Sleep quality showed a significant indirect association between PA and resilience, accounting for 18.2% of the total effect. Multi-group analyses suggested between-group differences in the PA→PSQI path: it was significant only in the General Sample but not in the Fitness-Remediation or Rehabilitation Sample. The direct PA → resilience path remained statistically significant across all three groups. Conclusions: University mental health programs should avoid a one-size-fits-all approach and instead adopt stratified, tailored interventions. For physically weak students, adaptive PA combined with targeted sleep-support strategies may be considered as part of resilience-related health promotion.