What is the clinical evidence from this study?

Study design: Cohort. Population: Ischemic heart disease (n=4952). Intervention: High level of physical activity during leisure time vs. Low level of physical activity during leisure time. Primary outcome: Ischemic heart disease (IHD) mortality among workers with high physical work demands (HR 0.82, 95% CI 0.42-1.56).

October 21, 2009Open Access

The interplay between physical activity at work and during leisure time – risk of ischemic heart disease and all-cause mortality in middle-aged Caucasian men

Key Result

A high level of physical activity during leisure time did not increase the risk of ischemic heart disease mortality among men with high physical work demands (HR 0.82).

Study Design

Type

Cohort (n=4,952)

Structured PICO

Does moderate or high physical activity during leisure time reduce ischemic heart disease mortality in middle-aged Caucasian men with varying physical work demands?

Population

4,952 Caucasian male workers aged 40-59 years without pre-existing clinical cardiovascular disease, followed for 30 years.

Exposure

Moderate or high level of physical activity during leisure time

Comparator

Low level of physical activity during leisure time

Outcome

Ischemic heart disease (IHD) mortalityhard clinical

Moderate and high levels of physical activity during leisure time are protective against IHD mortality even among men with medium and high physical activity at work, challenging the hypothesis that leisure activity harms those with physically demanding jobs.

Main Result

Hazard Ratio: 0.82 (95% CI 0.42–1.56)

Limitations

Information on physical activity at work and during leisure time was based on self-assessment, which entails some degree of misclassification.
Lack of continuous exposure data and repeated measures of exposure during the 30-year follow-up period.
Study population comprised only urban Danish male workers aged 40-59 years, limiting generalizability to women, younger workers, or other nationalities.

Abstract

OBJECTIVE: Our aim was to test the hypothesis that a high level of physical activity during leisure time increases the risk of ischemic heart disease (IHD) mortality among men with high physical work demands. METHODS: We carried out a 30-year follow-up of the Copenhagen Male Study of 5249 caucasian, male workers aged 40-59 years; 274 men with overt cardiovascular disease were excluded from the follow-up. RESULTS: During the follow-up period, 591 men (11.9%) died from IHD. Cox analyses of men with low (N=1236), medium (N=2651), and high (N=858) physical work demands showed that those with high demands had a higher risk of IHD mortality compared to men with low demands age-adjusted hazard ratio 1.51, 95% confidence interval (95% CI) 1.18-1.94. In all three groups, men with a low level of physical activity during leisure time had a higher risk of IHD than men with a medium or high level. Overall, the age-adjusted hazard ratio for IHD mortality associated with a high level of leisure time physical activity was 0.49 (95% CI 0.34-0.70). Among workers with high physical work demands, the hazard ratio for IHD mortality (adjusted for confounders) was 0.82 (95% CI 0.42-1.56) for a high level of leisure time physical activity and 0.62 (95% CI 0.40-0.97) for a moderate level. CONCLUSION: We did not find support for the hypothesis that a high level of physical activity during leisure time increases the risk of IHD mortality among men with high physical work demands and with no pre-existing clinical cardiovascular disease. In contrast, moderate and high levels of activity during leisure time seemed to be protective against IHD mortality among people with medium and high physical activity at work.

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