Journal of health research in community

Introduction
Work ability is recognized as a key determinant of employees’ health, productivity, and sustainable employability. According to the Job Demands–Resources (JD-R) model, work ability is influenced by the balance between occupational demands and available job resources. Excessive job demands may contribute to physical and psychological strain, whereas adequate job resources promote motivation, resilience, and occupational well-being. Teachers are among the most important occupational groups because they face substantial cognitive, emotional, and organizational demands while also playing a fundamental role in human capital development. Selection, optimization, and compensation (SOC) strategies have recently been proposed as self-regulatory mechanisms that may help individuals adapt to occupational challenges and maintain work ability. However, empirical evidence regarding the mediating role of SOC strategies among teachers, particularly in developing countries, remains limited. Therefore, this study aimed to investigate the relationship between job demands–resources and teachers’ work ability and to examine the mediating role of SOC strategies, using structural equation modeling. 

Methods
This cross-sectional analytical study was conducted among 310 teachers employed in public and private primary and secondary schools in Golbahar County, Iran, during the 2024–2025 academic year. Participants were selected using a multistage stratified cluster sampling method. Initially, schools were stratified into urban and rural categories, after which schools were randomly selected from each stratum. All eligible teachers within the selected schools were invited to participate voluntarily. 
Eligibility criteria included having at least one year of teaching experience, current employment as an active teacher, and willingness to participate. Questionnaires with more than 10% missing responses were excluded. 
Data were collected using a demographic characteristics form and three validated instruments. Work ability was assessed using the Work Ability Index (WAI), which evaluates current work ability, work-related diseases, sick leave, mental resources, and future expectations for work ability. Job demands and job resources were assessed using selected dimensions of the Copenhagen Psychosocial Questionnaire III (COPSOQ III) based on the JD-R framework. Personal adaptive capacity was evaluated using the Selection, Optimization, and Compensation (SOC) Questionnaire. 
Descriptive statistics were calculated for demographic and occupational variables. Normality assumptions were assessed before inferential analyses. Differences among work ability categories were examined using Kruskal–Wallis and Mann–Whitney U tests. Structural equation modeling (SEM) was subsequently employed to investigate both direct and indirect associations among job demands–resources, SOC strategies, and work ability while controlling for demographic variables, including age, sex, work experience, educational level, marital status, employment status, and perceived workload. Statistical analyses were performed using SPSS software,version 22 and AMOS version 24, with statistical significance set at P<0.05.

Results
A total of 310 teachers participated in the study, with a mean age of 35.6±8.9 years. Most participants were married (80.6%), employed in public schools (82.3%), and held a bachelor’s degree (62.9%). The majority reported a moderate perceived workload, while approximately one-third engaged in physical exercise at least twice per week.
The Work Ability Index (WAI) demonstrated generally favorable work ability among the study population. None of the participants were classified in the poor work ability category. Overall, 8.4% of teachers had moderate work ability, 43.2% had good work ability, and 48.4% demonstrated excellent work ability, indicating that more than 90% of participants maintained good or excellent work ability.
Comparative analyses revealed a statistically significant overall difference in JD-R scores across work ability categories (P=0.047). However, according to the post hoc Mann–Whitney U test, there was a significant difference only between teachers with good and excellent work ability (P=0.024), whereas comparisons involving the moderate work ability group did not reach statistical significance. Teachers with lower work ability tended to report relatively more unfavorable job demand–resource conditions.
Structural equation modeling (SEM) was subsequently conducted to simultaneously evaluate the direct and indirect relationships among job demands–resources, SOC strategies, and work ability. The initial structural model did not demonstrate acceptable goodness-of-fit indices. Therefore, theoretically justified model modifications were applied based on the modification indices. The revised model exhibited substantially improved fit and was considered appropriate for hypothesis testing. 
The standardized path coefficients indicated that job demands–resources were not significantly associated with SOC strategies (β=0.06, P=0.360). Likewise, the direct relationship between job demands–resources and work ability was not statistically significant (β=−0.20, P=0.067), although the observed trend suggested that unfavorable working conditions might be associated with reduced work ability. 
In contrast, SOC strategies showed a significant positive association with work ability (β=0.18, P=0.003), indicating that teachers who used adaptive self-regulatory strategies more frequently had better work ability. Furthermore, mediation analysis showed that the indirect effect of job demands–resources on work ability through SOC strategies was not statistically significant (P=0.252). Therefore, SOC strategies did not mediate the relationship between occupational demands–resources and work ability within the proposed structural model.

Conclusion
The findings indicate that teachers generally exhibited high levels of work ability despite experiencing considerable occupational demands. This favorable work ability may reflect the meaningful nature of the teaching profession, relatively stable employment conditions, supportive workplace environments, and strong intrinsic motivation. Although descriptive analyses suggested that more favorable job demand–resource conditions were associated with better work ability, these relationships were not confirmed in the SEM. Conversely, SOC strategies emerged as a significant predictor of work ability, highlighting the importance of adaptive self-regulation in maintaining occupational functioning. Teachers who effectively prioritized goals, optimized available resources, and compensated for limitations demonstrated better work ability. The absence of a significant mediating effect may be attributable to the cross-sectional design, limited variability in work ability scores, or contextual characteristics of the study population. These findings emphasize the potential value of interventions that strengthen SOC strategies to promote sustainable work ability among teachers, while encouraging future longitudinal studies to clarify causal mechanisms. 

Ethical Considerations
Compliance with ethical guidelines
The study protocol was approved by the Ethics Committee of Mazandaran University of Medical Sciences (Approval No. IR.MAZUMS.REC.1403.369). Written informed consent was obtained from all participants.

Funding
This study was funded by Mazandaran University of Medical Sciences (Research project code: 20650).

Authors contributions
Conceptualization and methodology: All authors; statistical analysis, investigation, writing, editing & review: Afsaneh Barahampoor and Solale Ramzani; supervision and project management: Siavash Etemadinezhad and Hajiomid Kalteh 

Conflicts of interest
The authors declared no conflicts of interest.

Acknowledgments
The authors would like to thank all teachers who participated in this study as well as the school administrators in Golbahar County. 

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