Introduction Musculoskeletal pain (MSP) can affect the functional capacity of workers and engender reduced work ability (WA). The effect of MSP on WA may differ between workers with and without heavy physical workload/low decision authority. Although MSP is widespread in the workforce, only a few studies have explored this hypothesis.

Objectives To investigate the separate and combined effects of MSP and heavy physical workload/low decision authority on poor self-reported physical WA.

Methods This study uses baseline data from the 2010 Stockholm Public Health Cohort (SPHC) questionnaire. The sample included 9419 workers with good baseline physical WA. Exposure to heavy physical workload and low decision authority were estimated using sex-specific job exposure matrices. The mean values for each exposure were dichotomised at the median (high/low) then combined with the presence of MSP. Follow-up data on poor self-reported physical WA were taken from the 2014 SPHC questionnaire. Logistic regression was performed adjusting for age, education, smoking, BMI, health conditions, psychological distress, and leisure-time physical activity. Additive interaction was estimated using the synergy index (SI).

Results MSP, heavy physical workload and low decision authority were separately associated with poor WA. MSP was associated with higher odds of poor WA than heavy physical workload/low decision authority for women, the opposite was observed for men. Combined exposure to MSP and heavy physical workload/low decision authority was associated with the highest odds of poor WA (e.g, MSP and heavy physical workload men: AOR: 4.04, 95%CI: 2.00–8.15; women: AOR: 3.25 95%CI: 1.81–5.83). However, the SI was non-statistically significant for both sexes.

Conclusion Combined exposure to MSP and heavy physical workload/low decision authority was associated with higher odds of poor WA than exposure to each factor separately. However, heavy physical workload/low decision authority did not statistically significantly aggravate the effect of MSP on the risk of poor WA.