Patients with heart disease face various challenges that healthy people do not. One of these is an increased likelihood of another heart attack, and the need for heavily monitored exercise. A new study published in the European Journal of Cardiovascular Prevention took a look at risk factors for poor health in cardiovascular patients, and found that those who sit a lot have worse health even if they exercise.

“Limiting the amount of time we spend sitting may be as important as the amount we exercise,” said lead author Dr. Stephanie Prince, post-doctorate fellow in the Division of Prevention and Rehabilitation, University of Ottowa Heart Institute, Ontario, Canada, in a press release. “Sitting, watching TV, working at a computer and driving in a car are all sedentary behaviors and we need to take breaks from them.”

There has been research on whether a sedentary lifestyle increases the risk of cardiovascular disease (spoiler alert: it does), but its effects on patients with previously established heart disease was unknown. The new study examined 278 patients with coronary heart disease, all of which had gone through a cardiac arrest program to help them learn about improving their levels of exercise in the long term.

During the study, patients wore an activity monitor during their waking hours. The monitors allowed scientists to track how long patients spend being sedentary, or doing light, moderate, or vigorous activity throughout the day. They also monitored other markers of health, including body mass index (BMI) and cardiorespiratory fitness. They compared these health markers with the amount of time a patient spent being sedentary.

The patients spent an average of eight hours each day being sedentary. “This was surprising given that they had taken classes on how to exercise more,” said Dr. Prince. "We assumed they would be less sedentary but they spent the majority of their day sitting.”

There were differences between the sexes, with men spending more time sitting than women, something Prince said needs to be researched more. There is some evidence that suggests men around the age of 60 become more sedentary than women and may watch more TV.

The researchers in the new study also found that patients who sat more had a higher BMI and lower levels of cardiorespiratory fitness. “These relationships remained even when we controlled for an individual’s age, gender or physical activity levels,” said Prince. “In other words, people who sat for longer periods were heavier and less fit regardless of how much they exercised.”

Dr Prince also emphasized that sitting less was not a replacement for exercise, saying it’s about the addition of sitting less to being physically active.

Source: Prince s, Blanchard C, Grace S, Reid R. Objectively-measured sedentary time and its association with markers of cardiometabolic health and fitness among cardiac rehabilitation graduates. European Journal of Preventative Cardiology. 2015.