Toronto: Heart patients should engage in light physical activities such as standing up or walking at casual pace for about seven minutes after every 20 minutes of sitting at a computer or watching television, suggests new research.

Previous research has shown that being sedentary for long periods could shorten life but taking breaks to move around may counteract the risk, particularly if it means burning more than 770 kcal a day.

This study, presented at the Canadian Cardiovascular Congress (CCC) 2018 in Toronto, investigated how many breaks, and for what duration, are needed to expend 770 kilocalorie (kcal).

"Our study shows that heart patients should interrupt sedentary time every 20 minutes with a 7 minute bout of light physical activity," said study author Ailar Ramadi from University of Alberta, Edmonton, Canada.

"Simple activities such as standing up and walking at a casual pace will expend more than 770 kcal in a day if done with this frequency and duration," Ramadi added.

The study enrolled 132 patients with coronary artery disease. The average age was 63 years and 77 per cent were male.

Participants wore an armband activity monitor for an average of 22 hours a day for five days.

The activity monitor recorded the amount of energy spent during breaks from inactivity, the amount of inactive time, and the number and duration of breaks during each sedentary hour.

"There is a lot of evidence now that sitting for long periods is bad for health," Ramadi said.

"Our study suggests that during each hour of sitting time, heart patients should take three breaks which add up to 21 minutes of light physical activity. This will expend 770 kcal a day, an amount associated with a lower risk of premature death," Ramadi added.