Objective The aim was to examine exposure-response relations between intensities of pushing/pulling, lifting/carrying loads and surgery for subacromial impingement syndrome (SIS) during a 10-year period.

Methods We conducted a register-based cohort study (2003–2008), comprising all persons born in Denmark (1933–1977) with at least 5 years of work experience (N=2 374 403). Information on SIS surgery was retrieved from the Danish National Patient Register (N=14 188). Occupational mechanical exposures comprising lifting or carrying loads ≥10 kg and pushing or pulling loads ≥50 kg were assessed by combining individual job codes with our expert-based Shoulder job exposure matrix. We created 3 intensity-specific exposure duration variables by dividing the intensity for lifting/carrying and pushing/pulling into categories (low, medium, and high), and summed up the number of years in each exposure category for a 10-year time window. The association was analyzed using logistic regression as survival analysis.

Results The adjusted odds ratio (ORadj) increased with both exposure duration and intensity of lifting/carrying and pushing/pulling. ORadj reached a maximum of 1.78 (95% CI 1.66–1.89), 2.52 (95% CI 2.32–2.74), and 2.96 (95% CI 2.53–3.47) after 10 years of exposures for the three exposure intensities. For pushing/pulling, maximum ORadj was 1.44 (95% CI 1.31–1.58), 1.68 (95% CI 1.58–1.79), and 1.72 (95% CI 1.50–2.00), respectively.

Conclusion We found exposure-response relations for both lifting/carrying and pushing/pulling across the 10-year time window. The risk was especially pronounced for lifting/carrying compared to pushing/pulling. We did not find indications of safe exposure intensities.