Short-term changes in behavioral determinants following a theory-based workplace musculoskeletal health program among...

Work-related musculoskeletal disorders (WMSDs) are a major occupational and public health burden among manufacturing workers. Existing workplace interventions often emphasize ergonomic assessment or generic safety education, with limited use of behavior-change theory. We examined short-term changes in Theory of Planned Behavior (TPB)-based determinants and self-reported preventive behavior following an on-site, nurse-delivered musculoskeletal-health program.

A two-cluster, cluster-allocated controlled program evaluation was conducted in two plants in City D, Republic of Korea (N = 69; intervention n = 34, control n = 35), with assessments at baseline, week 4, and week 8. Male field workers with self-reported musculoskeletal symptoms identified through workplace ergonomic risk assessment were recruited; plant-level allocation was random, although balance cannot be assumed with only two clusters. The 4-week intervention comprised 4 weekly education sessions plus thrice-weekly small-group activities; controls received routine workplace safety education without attention-matching. Outcomes were four TPB constructs, a single-item self-reported behavior item, and NIOSH-based musculoskeletal symptoms. Generalized estimating equations modeled continuous outcomes; dichotomous outcomes were examined using Pearson chi-square and exact tests as appropriate. The study was not prospectively registered.

Significant group-by-time interactions were observed for PBC (χ² = 12.92, p < 0.001) and behavioral intention (χ² = 10.88, p = 0.001), but not for attitude or subjective norms. Follow-up between-group standardized mean differences were d = 0.58 (95% CI 0.10-1.06) for PBC and d = 0.40 (95% CI -0.08-0.87) for intention. Self-reported preventive behavior increased in the intervention group from 29.4% at baseline to 100.0% post-intervention and 82.4% at follow-up, compared with 31.4% and 25.7% in controls at the corresponding timepoints (both between-group p < 0.001; follow-up RR 3.20, 95% CI 1.79-5.74); the 100% post-intervention rate reflects single-item self-report limitations. Overall NIOSH symptom-carrier status did not differ between groups at any timepoint.

The program was accompanied by short-term changes in PBC, behavioral intention, and self-reported preventive behavior. Given the two-cluster design, non-attention-matched control, single-item behavioral outcome, and absence of prospective registration, these findings should be interpreted as feasibility- and mechanism-oriented signals rather than evidence of efficacy.