The first large study showing that leisure time physical activity and occupational physical activity have opposite, and independent, associations with cardiovascular disease risk and longevity has been published.
"We adjusted for multiple factors in our analysis, indicating that the relationships were not explained by lifestyle, health conditions or socioeconomic status," said study author Professor Andreas Holtermann of the National Research Centre for the Working Environment-Copenhagen, Denmark.
The World Health Organisation (WHO) recommends physical activity during both recreation and work to improve health.
Previous studies have suggested that occupational activity is related to an increased risk for heart disease and mortality but have been too small to fully explain whether this was due to the manual work or because employees had unhealthy lifestyles or low socioeconomic status (low level of education).
This study included 104,046 women and men aged 20-100 years from the Copenhagen General Population Study with baseline measurements in 2003-2014. Participants completed questionnaires about activity during leisure and employment and were categorised as low, moderate, high, or very high activity for each.
During a median follow-up of 10 years, there were 9,846 (9.5%) deaths from all causes and 7,913 (7.6%) major adverse cardiovascular events (MACE, defined as fatal and nonfatal myocardial infarction, fatal and non-fatal stroke, and other coronary death).
Compared to low leisure time physical activity, after adjustment for age, sex, lifestyle, health, and education, moderate, high, and very high activity were associated with 26%, 41%, and 40% reduced risks of early death, respectively. In contrast, compared to low work activity, high and very high activity were associated with 13% and 27% increased risks of death, respectively.
Similarly, after adjustments, compared to low leisure activity, moderate, high, and very high levels of leisure activity were associated with 14%, 23%, and 15% reduced risks of MACE, respectively. Compared to low work activity, high and very high levels were associated with 15% and 35% increased risks of MACE, respectively.
Holtermann said: "Many people with manual jobs believe they get fit and healthy by their physical activity at work and therefore can relax when they get home. Unfortunately, our results suggest that this is not the case. And while these workers could benefit from leisure physical activity, after walking 10,000 steps while cleaning or standing seven hours in a production line, people tend to feel tired so that's a barrier."
While the study did not investigate the reasons for the opposite associations for occupational and leisure time physical activity, Holtermann said: "A brisk 30-minute walk will benefit your health by raising your heart rate and improving your cardiorespiratory fitness, while work activity often does not sufficiently increase heart rate to improve fitness. In addition, work involving lifting for several hours a day increases blood pressure for many hours, which is linked with heart disease risk, while short bursts of intense physical activity during leisure raises blood pressure only briefly."
Holtermann's vision is to re-organise occupational activity so that it mimics the beneficial aspects of leisure exercise. Several approaches are being piloted, such as rotating between workstations on a production line so that employees do a "healthy mixture" of sitting, standing, and lifting during a shift. In another study, childcare workers play games together with children, instead of observing, so that both get their heart rate up and increase fitness. "We are trying to vary the tasks, give recovery time, or raise heart rate so there is a fitness and health benefit," he said.
Holtermann concluded: "Societies need adults with sufficient health and fitness to work longer since the retirement age is increasing. We need to find ways to make active work good for health."
Funding: This work was supported by the Capital Region of Copenhagen, Danish Heart Foundation, Danish Lung Association, Velux Foundation, and Lundbeck Foundation.
The physical activity paradox in cardiovascular disease and all-cause mortality: the contemporary Copenhagen General Population Study with 104,046 adults
Andreas Holtermann, Peter Schnohr, Børge Grønne Nordestgaard, Jacob Louis Marott
Published in the European Heart Journal on 8 April 2021
Leisure time physical activity associates with reduced risk of cardiovascular disease and all-cause mortality, while these relationships for occupational physical activity are unclear. We tested the hypothesis that leisure time physical activity associates with reduced major adverse cardiovascular events (MACE) and all-cause mortality risk, while occupational physical activity associates with increased risks.
Methods and results
We studied 104 046 women and men aged 20–100 years in the Copenhagen General Population Study with baseline measurements in 2003–2014 and median 10-year follow-up. Both leisure and occupational physical activity were based on self-report with four response categories. We observed 7913 (7.6%) MACE and 9846 (9.5%) deaths from all causes. Compared to low leisure time physical activity, multivariable adjusted (for lifestyle, health, living conditions, and socioeconomic factors) hazard ratios for MACE were 0.86 (0.78–0.96) for moderate, 0.77 (0.69–0.86) for high, and 0.85 (0.73–0.98) for very high activity; corresponding values for higher occupational physical activity were 1.04 (0.95–1.14), 1.15 (1.04–1.28), and 1.35 (1.14–1.59), respectively. For all-cause mortality, corresponding hazard ratios for higher leisure time physical activity were 0.74 (0.68–0.81), 0.59 (0.54–0.64), and 0.60 (0.52–0.69), and for higher occupational physical activity 1.06 (0.96–1.16), 1.13 (1.01–1.27), and 1.27 (1.05–1.54), respectively. Similar results were found within strata on lifestyle, health, living conditions, and socioeconomic factors, and when excluding individuals dying within the first 5 years of follow-up. Levels of the two domains of physical activity did not interact on risk of MACE (P = 0.40) or all-cause mortality (P = 0.31).
Higher leisure time physical activity associates with reduced MACE and all-cause mortality risk, while higher occupational physical activity associates with increased risks, independent of each other.
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