May 12, 2010
Long Overtime Work Boosts Heart Risk?

Civil servants who work a lot of overtime suffer more heart disease.

Working overtime is bad for the heart according to results from a long-running study following more than 10,000 civil servants in London (UK): the Whitehall II study.

The research, which is published online today (Wednesday 12 May) in the European Heart Journal [1], found that, compared with people who did not work overtime, people who worked three or more hours longer than a normal, seven-hour day had a 60% higher risk of heart-related problems such as death due to heart disease, non-fatal heart attacks and angina.

Dr Marianna Virtanen, an epidemiologist at the Finnish Institute of Occupational Health, Helsinki (Finland) and University College London (UK), said: "The association between long hours and coronary heart disease was independent of a range of risk factors that we measured at the start of the study, such as smoking, being overweight, or having high cholesterol.

3 to 4 hours of overtime per day are associated with a 60% boost in coronary heart disease risk.

During the average 11.2 years of follow-up, Dr Virtanen and her colleagues in Finland, London and France, found that there had been 369 cases of fatal CHD, non-fatal heart attacks (myocardial infarctions) or angina. After adjusting for sociodemographic factors such as age, sex, marital status and occupational grade, they found that working three to four hours overtime (but not one to two hours) was associated with a 60% higher rate of CHD compared with no overtime work. Further adjustments for a total of 21 risk factors made little difference to these estimates.

Could be that sitting too much is part of the problem with overtime. If you are tied to your desk for long hours you aren't out getting needed exercise.

Share |      Randall Parker, 2010 May 12 12:48 AM  Aging Lifestyle Studies

Lou Pagnucco said at May 13, 2010 10:29 AM:

This study focused on office workers who (presumably) sit while working.
I'd like to know whether mobile/manual workers experience the same risks. I'd wager not.
Overseas air passengers appear to suffer from leg clots often.

There is other evidence that sitting for extended periods increases cardiac and stroke risk.

'Sitting Too Long Can Cause Rogue Blood Clots'

'Sitting in Front of TV Increases the Risk or Stroke or Heart Attack by 80 Percent'

I wonder whether low-dose aspirin, or perhaps low-frequency vibrating seat cushions might prevent dangerous emboli from forming in people who sit for extended periods.

'Non-invasive low frequency vibration as a potential emergency adjunctive treatment for heart attack and stroke'

Randall Parker said at May 15, 2010 10:33 AM:


Surely there must be a study about life expectancy of US Post Office letter carriers.

Sitting and blood clots: For this reason I get up and take short and long walks during my work day.

I wonder what risks come from lying down. We sleep lying down. How risky is that?

Nick G said at May 15, 2010 12:28 PM:

It seems we're not designed to sit:

"New research in the diverse fields of epidemiology, molecular biology, biomechanics, and physiology is converging toward a startling conclusion: Sitting is a public-health risk. And exercising doesn't offset it. "People need to understand that the qualitative mechanisms of sitting are completely different from walking or exercising," says University of Missouri microbiologist Marc Hamilton. "Sitting too much is not the same as exercising too little. They do completely different things to the body."

Hamilton, like many sitting researchers, doesn't own an office chair. "If you're standing around and puttering, you recruit specialized muscles designed for postural support that never tire," he says. "They're unique in that the nervous system recruits them for low-intensity activity and they're very rich in enzymes." One enzyme, lipoprotein lipase, grabs fat and cholesterol from the blood, burning the fat into energy while shifting the cholesterol from LDL (the bad kind) to HDL (the healthy kind). When you sit, the muscles are relaxed, and enzyme activity drops by 90% to 95%, leaving fat to camp out in the bloodstream. Within a couple hours of sitting, healthy cholesterol plummets by 20%.

...The data back him up. Older people who move around have half the mortality rate of their peers. Frequent TV and Web surfers (sitters) have higher rates of hypertension, obesity, high blood triglycerides, low HDL cholesterol, and high blood sugar, regardless of weight. Lean people, on average, stand for two hours longer than their counterparts.

...The best sitting alternative is perchinga half-standing position at barstool height that keeps weight on the legs and leaves the S-curve intact. Chair alternatives include the Swopper, a hybrid stool seat and the funky, high HAG Capisco chair. Standing desks and chaise longues are good options. Ball chairs, which bounce your spine into a C-shape, are not. The biggest obstacle to healthy sitting may be ourselves. Says Jackie Maze, the vice-president for marketing at Keilhauer: "Most want familiar chairs"

Lou Pagnucco said at May 16, 2010 10:01 AM:

Nick G,

Good stuff. I also found studies indicating that even activity which doesn't affect recognized risk factors (HDL, LDL, Hb1Ac, blood pressure) still reduces mortality. I wonder whether technology could devise seating which forces the use of more muscle groups and prevents clotting.


I can't find any studies which really tease out the effect of sitting time/duration from a myriad of confounding factors. However, I found the following study which explores the nonlinear influences of occupational mobility, smoking and alcohol consumption interesting.

'Alcohol and survival in the Italian rural cohorts of the Seven Countries Study'

"RESULTS: During a period of 30 years 1096 deaths occurred. Age-adjusted life expectancy for men assuming a mean daily quantity of 63 g of alcohol (range 47 drinks per day) was 21.6 0.4 years, roughly 2 years more than men taking a mean quantity of 3.7 g (10 drinks per day. Taking smoking habit into account, the longest survival of 22.4 0.5 years was observed in non-smokers drinking 47 drinks daily; the lowest, 18.5 0.7 years, in smokers drinking >10 drinks. Stratifying for physical activity, the longest survival (23.4 0.7 years) was experienced by men engaged in heavy physical activity at work drinking 14 drinks per day.

CONCLUSIONS: The relationship between life expectancy and alcohol consumption (97% wine in this Italian cohort and mostly red wine) is confirmed to be non-linear. Men aged 4564 at entry drinking about 5 drinks per day have a longer life expectancy than occasional and heavy drinkers.

...In our cohort, (although HDL cholesterol was not measured and therefore this hypothesis cannot be verified from our data), workers with heavy physical activity have the greatest life expectancy when their alcohol consumption is relatively low, while for sedentary workers the longest survival corresponds to an intake of quite heavy amounts of alcohol. This observation suggests that the benefits from alcohol and physical activity do not necessarily add together, and instead a saturation effect takes place."

Wouldn't it be nicer to live in a more linear world?

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