Objectives To prospectively examine the independent and combined effect of occupational physical activity and metabolic syndrome on all-cause and cardiovascular mortality in a large population-based cohort.

Methods Data on 37 300 men and women participating in the Norwegian HUNT Study (1995–1997) were linked with the Cause of Death Registry at Statistics Norway. Cox proportional HR with 95% CI were estimated.

Results During a median follow-up of 12.4 years, a total of 1168 persons died. Of these, 278 died from cardiovascular disease. Persons with metabolic syndrome and much walking/lifting at work had a HR of 1.79 (95% CI 1.20 to 2.66) for cardiovascular death referencing persons without metabolic syndrome and much walking/lifting. Using the same reference, persons with metabolic syndrome and sedentary work had a HR of 2.74 (95% CI 1.82 to 4.12) while persons with metabolic syndrome and heavy physical work had a HR of 3.02 (95% CI 1.93 to 4.75). Associations with all-cause mortality were somewhat weaker, and were largely due to deaths from cardiovascular disease.

Conclusions The association between metabolic syndrome and cardiovascular mortality is stronger for persons with sedentary work and with physically heavy work than for persons with much walking/lifting at work.