Physical demands at work, physical fitness, and 30-year ischaemic heart disease and all-cause mortality in the Copenhagen Male Study.
OBJECTIVE
No previous long-term prospective studies have examined if workers with low cardiorespiratory fitness have an increased risk of cardiovascular mortality due to high physical work demands. We tested this hypothesis.


METHODS
We carried out a 30-year follow-up of the Copenhagen Male Study of 5249 employed men aged 40-59 years. We excluded from follow-up 274 men with a history of myocardial infarction, prevalent symptoms of angina pectoris, or intermittent claudication. We estimated physical fitness [maximal oxygen consumption (VO (2)Max)] using the Astrand cycling test and determined physical work demands with two self-reported questions.


RESULTS
In the Copenhagen Male Study, 587 men (11.9%) died due to ischaemic heart disease (IHD). Using men with low physical work demands as the reference group, Cox analyses--adjusted for age, blood pressure, smoking, alcohol consumption, body mass index, diabetes, and hypertension--showed that high physical work demands were associated with an increased risk of IHD mortality in the least fit [VO (2)Max range 15-26, N=892, hazard ratio (HR) 2.04, 95% confidence interval (95% CI) 1.20-3.49] and moderately fit (VO (2)Max range 27-38, N=3037, HR 1.75, 95% CI 1.24-2.46), but not among the most fit men (VO (2)Max range 39-78, N=1014, HR 1.08, 95% CI 0.52-2.17). We found a similar, although slightly weaker, relationship with respect to all-cause mortality.


CONCLUSIONS
The hypothesis was supported. Men with low and medium physical fitness have an increased risk of cardiovascular and all-cause mortality if exposed to high physical work demands. Ours observations suggest that, among men with high physical work demands, being physically fit protects against adverse cardiovascular effects.
Holtermann
Andreas
A
National Research Centre for the Working Environment, Lersø Parkallé 105, 2100 Copenhagen Ø, Denmark. aho@nrcwe.dk
Mortensen
Ole Steen
OS
Burr
Hermann
H
Søgaard
Karen
K
Gyntelberg
Finn
F
Suadicani
Poul
P
D000328:Adult; D001642:Bicycling / Q000502:physiology; D016001:Confidence Intervals; D003718:Denmark / Q000453:epidemiology; D006339:Heart Rate; D006801:Humans; D008019:Life Style; D008297:Male; D008875:Middle Aged; D009026:Mortality / Q000639:trends*; D009043:Motor Activity / Q000502:physiology*; D015999:Multivariate Analysis; D017202:Myocardial Ischemia / Q000453:epidemiology / Q000401:mortality*; D016272:Occupational Health; D010101:Oxygen Consumption; D010809:Physical Fitness / Q000502:physiology*; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012044:Regression Analysis; D018570:Risk Assessment; D011795:Surveys and Questionnaires; D013997:Time Factors; D016526:Workload