Standing too long at work carries twice the risk of heart disease as sitting too long

Workers who stand on the job most of the time are at greater risk of heart disease than workers who predominantly sit.

According to a study conducted by the Institute for Work & Health (IWH) and the Institute for Clinical Evaluative Sciences (ICES), people who primarily stand on the job are twice as likely as people who primarily sit on the job to have a heart attack or congestive heart failure. That’s even after taking into account a wide range of personal, health and work factors.

Workplaces have been hearing a lot lately about the health effects of prolonged sitting on the job, says IWH Senior Scientist Dr. Peter Smith, who led the study. Our results suggest that workplaces also need to pay attention to the health effects of prolonged standing, and target their prevention programs accordingly.

The study has been published as an open access article in the American Journal of Epidemiology (doi: 10.1093/aje/kwx298).

The study followed 7,300 Ontario workers, aged 35-74, for 12 years. All were initially free of heart disease. These workers were respondents to the 2003 Canadian Community Health Survey (CCHS), a Statistics Canada survey that collected information on personal factors, health conditions, health behaviours and work conditions. It also collected job title information, which the research team used—along with job exposure information in the Human Resources and Skills Development Canada Career Handbook—to estimate respondents’ body postures at work. The team then categorized respondents into four categories, according to the predominant body postures they used in their jobs.

Among the respondents included in the study, nine per cent were estimated to predominantly stand at work. The people in this category worked as salespeople, cooks, food servers, bank tellers, machinists and tool operators, among others.

The 37 per cent in the second category were estimated to predominantly sit, working as truck drivers, administrative officers, clerks, secretaries, business and management professionals, etc. The third category, consisting of jobs that involved a mix of sitting, standing and walking, included teachers, nurses, couriers, motor vehicle assemblers, etc. Finally, the fourth category was made up of jobs that involved other body postures (bending, kneeling), jobs such as mechanics, material handlers, orderlies, cleaners, shippers and receivers.

The researchers linked the 2003 CCHS information to administrative health records housed at ICES to identify people who had a new case of heart disease during the next 12 years. During this period, 3.4 per cent of the study group developed heart disease—more men (4.6 per cent) than women (2.1 per cent). Without taking any other factors into account (the unadjusted risk), the risk of heart disease was higher among people whose jobs required mostly standing (6.6 per cent) than among people whose jobs involved mostly sitting (2.8 per cent).  The unadjusted risk of heart disease among people who stood on the job was even slightly higher than that of people who smoked daily (5.8 per cent).

Even after adjusting for a wide range of factors—including personal (e.g. age, gender, education level, ethnicity, immigrant status, marital status), health condition (e.g. diabetes, arthritis, hypertension, mood and anxiety disorders), health behaviour (e.g. smoking, drinking, body mass index, exercise) and work (e.g. physical demands, shift schedule)—the risk of heart disease was still twice as high among people who primarily stood on the job as among those who primarily sat.

A combination of sitting, standing and moving on the job is likely to have the greatest benefits for heart health, says Smith. Workplaces need to apply this message not just to workers who predominantly sit, but also—in fact, especially—to workers who predominantly stand.

That said, workplaces need to look beyond job activity to truly protect the cardiovascular health of workers. While jobs that involved a combination of sitting, standing and walking were shown in this study to be associated with 40 per cent lower risk of heart disease among men, these jobs didn’t result in a decreased risk among women. This may be due to the fact that nurses and teachers accounted for most of the jobs held by women in the “sitting, standing and walking” category, jobs known to be stressful in different ways.

Prevention programs that focus only on physical job activity, while ignoring other factors such as the psychosocial environment, are unlikely to lead to meaningful changes in cardiovascular risk, Smith says.

Source:  At Work, Issue 90, Fall 2017: Institute for Work & Health, Toronto

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