Healthy old manPeople who have heart disease and spend a lot of time sitting have worse health than their more active peers, new research has revealed.

Until now research had focused on the risks to cardiovascular health caused by a sedentary lifestyle, establishing that less activity increases the risk of developing cardiovascular disease. Yet this new study is one of the first to look at the risks of a sedentary lifestyle on patients with established heart disease.

The current study investigated levels of sedentary behaviour and the effect on health in 278 patients with coronary artery disease. The patients had been through a cardiac rehabilitation programme that taught them how to improve their levels of exercise in the long-term.

Patients wore an activity monitor during their waking hours for nine days. The monitors allowed the researchers to measure how long patients spent being sedentary, or doing light, moderate or vigorous levels of physical activity.

The researchers also assessed various markers of health including body mass index (BMI, in kg/m2) and cardiorespiratory fitness. They also looked at whether the amount of time a person spent inactive – or being sedentary – was related to these markers of health.

The researchers found that patients with coronary artery disease spent an average of eight hours each day being sedentary.

It was also found that men were more inactive than women – by approximately 1 hour a day. This was primarily because women tended to do more light intensity movement, such as housework or running errands.

Generally, patients who sat more had a higher BMI. They also had lower cardiorespiratory fitness, which was assessed using VO2 peak. This is the maximum rate at which the heart, lungs and muscles use oxygen during an exercise test (also called aerobic capacity).

“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 Ottawa Heart Institute, Ontario, Canada. “Sitting, watching TV, working at a computer and driving in a car are all sedentary behaviours and we need to take breaks from them.”

A number of practical tips to get moving were proposed. These include:

  • Getting up and move every 30 minutes
  • Standing up during TV commercials or, even better, do light exercises while watching TV
  • Setting a timer and take regular breaks from your desk
  • Taking lunch breaks outside instead of in front of the computer
  • Going to bed instead of sitting in front of the TV and get the benefits of sleeping
  • Monitoring activity patterns to find out when you are most sedentary.

Dr Prince emphasised that sitting less was not a replacement for exercise. “It’s important to limit prolonged bouts of sitting and in addition to be physically active,” she said. “Sedentary time may be another area of focus for cardiac rehabilitation programmes along with exercise.”