Prolonged sitting worsens the health of heart disease patients even with exercise, study finds

Patients suffering from heart diseases who sit a lot have worse health even if they exercise, a new study finds.

Researchers at the University of Ottawa Heart Institute say limiting the amount of time spent on sitting may be as important as the amount of exercise being done. Sitting, watching TV, working at a computer and driving in a car are all sedentary behaviours, and people, especially those with heart disease, need to take breaks from these sedentary activities, according to the team.

While a growing number of studies show that being sedentary increases the risk of cardiovascular disease, its effect on patients with established heart disease is still unknown.

In the current study published in the European Journal of Cardiovascular Prevention, the researchers investigated levels of sedentary behaviour and the effect on health in more than 200 patients with coronary artery disease. The patients had undergone a cardiac rehabilitation programme which taught them how to improve their levels of exercise in the long term.

For a span of nine days, patients were made to wear an activity monitor during their waking hours. These monitors allowed the researchers to measure how long patients spent being sedentary, or doing light, moderate or vigorous levels of physical activity.

The team also assessed various markers of health including body mass index or BMI and cardiorespiratory fitness. In addition, they looked at whether the amount of time a person spent being sedentary, which was mainly sitting, was related to these markers of health.

Their findings showed that patients with coronary artery disease spent an average of eight hours each day being sedentary. “This was surprising given that they had taken classes on how to exercise more. We assumed they would be less sedentary but they spent the majority of their day sitting," says the lead author Dr Stephanie Prince, post-doctorate fellow in the Division of Prevention and Rehabilitation at the University of Ottawa Heart Institute.

Men spent more time sitting than women, averaging one hour more each day, the team also found. This was primarily because women tended to do more light intensity movement, such as light housework, walking to the end of the drive, or running errands.

While Prince and her team are yet to establish the reason why women with coronary artery disease spend less time sitting for long periods, there has been previous research suggesting that men who are around 60 years old become more sedentary than women and may watch more TV.

The researchers found that patients who sat more had a higher BMI, as well as lower cardiorespiratory fitness.

Prince emphasised that their study does not recommend sitting less as replacement for exercise. “It's important to limit prolonged bouts of sitting and in addition to be physically active. Sedentary time may be another area of focus for cardiac rehabilitation programs along with exercise,” she noted.

A September 2015 study showed that fidgeting or restless movements may counteract the harmful health impact of prolonged sitting. A team of researchers, co-led by the University of Leeds and University College London, discovered that people who consider themselves as moderately or very fidgety do not increase their risk of early death from sitting for long periods.

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