title: Occupational physical activity, energy expenditure and 11-year progression of carotid atherosclerosis.
abstract: OBJECTIVE
  This study prospectively assessed the effects of occupational physical activity on atherosclerosis progression.
  
  
  METHODS
  This population-based prospective study of ultrasonographically assessed carotid intima media thickness (IMT) used repeated measures of occupational physical activity during baseline, 4-year, and 11-year examinations of 612 Finnish men 42-60 years of age at baseline. The association between five measures of energy expenditure and the 11-year change in maximum IMT was evaluated in regression models adjusting for 21 potential confounders, including biological factors, leisure-time physical activity, smoking, socioeconomic status, psychosocial job factors, and baseline health status.
  
  
  RESULTS
  At baseline, 31% of all the men and 51% of those with ischemic heart disease (IHD) exceeded the recommended maximum levels of relative aerobic strain. All five measures of energy expenditure were significantly associated with adjusted 11-year IMT change. Significant interactions were found between IHD and several measures of energy expenditure. Maximum relative aerobic strain resulted in a 90% increase in IMT among the men with IHD compared with a 46% increase among those without IHD. The men with preexisting carotid stenosis also had higher rates of IMT progression than the men without this condition.
  
  
  CONCLUSIONS
  This study shows that high energy expenditures at work are associated with an accelerated progression of atherosclerosis even after control for virtually all known cardiovascular risk factors, especially among older workers and workers with preexisting IHD or carotid artery stenosis. The findings support the hemodynamic theory of atherosclerosis and have important implications for workplace surveillance and disease prevention.
authors.affiliation: Department of Medicine, University of California at San Francisco, UC Berkeley Richmond Field Station, Richmond CA 94804, USA. nkrause@berkeley.edu
authors.forename: Niklas
authors.initials: N
authors.lastname: Krause
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Brand
authors.forename: George A
authors.initials: GA
authors.lastname: Kaplan
authors.forename: Jussi
authors.initials: J
authors.lastname: Kauhanen
authors.forename: Smriti
authors.initials: S
authors.lastname: Malla
authors.forename: Tomi-Pekka
authors.initials: TP
authors.lastname: Tuomainen
authors.forename: Jukka T
authors.initials: JT
authors.lastname: Salonen
mesh_terms: D000328:Adult; D002340:Carotid Artery Diseases / Q000000981:diagnostic imaging / Q000503:physiopathology*; D018450:Disease Progression; D004734:Energy Metabolism; D015444:Exercise; D005387:Finland; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D017202:Myocardial Ischemia / Q000150:complications; D009790:Occupations; D011446:Prospective Studies; D011584:Psychology; D012044:Regression Analysis; D017539:Tunica Intima / Q000000981:diagnostic imaging; D017540:Tunica Media / Q000000981:diagnostic imaging; D014463:Ultrasonography; D016526:Workload