title: High occupational physical activity and risk of ischaemic heart disease in women: the interplay with physical activity during leisure time.
abstract: BACKGROUND
  Recent studies indicate that physically demanding work is a risk factor for heart disease among men, especially those with low or moderate physical activity during leisure time. Among women, present evidence is inconclusive.
  
  
  METHODS
  The design was a prospective cohort study.
  
  
  METHODS
  This investigation in the Danish Nurse Cohort Study included 12,093 female nurses aged 45-64 years, who answered a self-report questionnaire on physical activity at work and during leisure time, known risk factors for ischaemic heart disease (IHD) and occupational factors at baseline in 1993. Information on the 15-year incidence of IHD was obtained by individual linkage in the National Register of Hospital Discharges to 2008.
  
  
  RESULTS
  During follow-up 580 participants were hospitalised with IHD. A significant interaction between occupational and leisure time physical activity was found with the lowest risk of IHD among nurses with the combination of moderate physical activity at work and vigorous physical activity during leisure time. Compared to this group high physical activity at work was associated with a higher risk of IHD at all levels of physical activity during leisure time increasing from hazard ratio 1.75 (95% confidence interval (CI) 1.10-2.80) among nurses with vigorous physical activity during leisure time to 2.65 (95% CI 1.44-4.88) among nurses being sedentary during leisure time.
  
  
  CONCLUSIONS
  This study among Danish nurses suggests that high physical activity at work is a risk factor for IHD among women. Vigorous physical activity during leisure time lowered but did not completely counteract the adverse effect of occupational physical activity on risk of IHD.
authors.affiliation: Research Centre for Prevention and Health, Glostrup University Hospital, Denmark Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Denmark karen.allesoee@regionh.dk.
authors.forename: Karen
authors.initials: K
authors.lastname: Allesøe
authors.affiliation: National Research Centre for the Working Environment, Denmark.
authors.forename: Andreas
authors.initials: A
authors.lastname: Holtermann
authors.affiliation: Research Centre for Prevention and Health, Glostrup University Hospital, Denmark.
authors.forename: Mette
authors.initials: M
authors.lastname: Aadahl
authors.affiliation: Department of Occupational and Environmental Medicine, Bispebjerg University Hospital, Denmark.
authors.forename: Jane F
authors.initials: JF
authors.lastname: Thomsen
authors.affiliation: Research Centre for Prevention and Health, Glostrup University Hospital, Denmark.
authors.forename: Yrsa A
authors.initials: YA
authors.lastname: Hundrup
authors.affiliation: Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Denmark.
authors.forename: Karen
authors.initials: K
authors.lastname: Søgaard
mesh_terms: D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D007587:Job Description; D007899:Leisure Activities; D008875:Middle Aged; D009043:Motor Activity; D017202:Myocardial Ischemia / Q000175:diagnosis / Q000453:epidemiology* / Q000517:prevention & control; D009726:Nurses; D016272:Occupational Health; D011446:Prospective Studies; D065840:Protective Factors; D018570:Risk Assessment; D012307:Risk Factors; D057185:Sedentary Behavior; D012737:Sex Factors; D013997:Time Factors; D016387:Women's Health; D016526:Workload
keywords: Epidemiology; heart disease; occupational health; physical activity; prospective study; women