People who sit or remain sedentary for more than 14 hours a day, on average, may have a higher risk of a cardiovascular event or death in the year after treatment at a hospital for symptoms of a heart attack such as chest pain, according to new research published today in the American Heart Association's peer-reviewed scientific journal Circulation: Cardiovascular Quality and Outcomes.

Previous research from the study authors found that people who had experienced a heart attack were spending up to 12 to 13 hours each day being sedentary, defined as any awake activity that involved little-to-no physical movement. In this study, the researchers used a wrist accelerometer to track the amount of time each participant spent moving or being sedentary for a median of 30 days after discharge from a hospital's emergency department.

Wrist accelerometers measure the acceleration of motion in three directions — forwards and backwards, side-to-side, and up and down. These measurements allowed the researchers to infer the intensity of a participant's physical activity, and they provide more accurate measurements of the participants' time spent moving, rather than asking participants to remember. Some examples of moderate-intensity physical activities are brisk walking, water aerobics, dancing, playing doubles tennis, or gardening, and examples of vigorous-intensity activities are running, lap swimming, heavy yardwork such as continuous digging or hoeing, playing singles tennis, or jumping rope.

"Current treatment guidelines after a cardiac event focus mainly on encouraging patients to exercise regularly," said study lead author Keith Diaz, Ph.D., the Florence Irving Associate Professor of Behavioral Medicine at Columbia University Medical Center in New York City, a certified exercise physiologist, and a volunteer member of the American Heart Association's Physical Activity Science Committee. "In our study, we explored whether sedentary time itself may contribute to cardiovascular risk."

Researchers followed more than 600 adults, ages 21 to 96, treated for a heart attack or chest pain in the emergency department at a single hospital system in New York City. Participants wore a wrist accelerometer for a median of 30 consecutive days after hospital discharge to measure the amount of time they spent sitting or being inactive each day. Additional cardiac events and deaths were evaluated one year after hospital discharge via phone surveys with patients, electronic health records, and the Social Security Death Index. The study was focused on understanding the risk of sedentary behaviour and identifying modifiable risk factors that may improve long-term outcomes in this high-risk group.

The analysis found:

"We were surprised that replacing sedentary time with sleep also lowered risk. Sleep is a restorative behaviour that helps the body and mind recover, which is especially important after a serious health event like a heart attack," Diaz said. "Our study indicates that one doesn't have to start running marathons after a cardiovascular event to see benefits. Sitting less and moving or sleeping a little more can make a real difference. More physical activity and more sleep are healthier than sitting, so we hope these findings support health professionals to move toward a more holistic, flexible, and individualised approach for physical activity in patients after a heart attack or chest pain."

Physical activity and sleep are both key components of the American Heart Association's Life's Essential 8, a list of health behaviours and factors that support optimal cardiovascular health. Poor sleep is a known risk factor for cardiovascular disease, which claims more lives each year in the U.S. than all forms of cancer and chronic lower respiratory disease combined, according to the American Heart Association's 2025 Statistical Update. In addition to sleep duration, a recent scientific statement from the association highlighted the importance of sleep continuity, sleep timing, sleep satisfaction, sleep regularity, sleep-related daytime functioning, and sleep architecture in cardiometabolic health.

The study had several limitations, including that the definition of sedentary behaviour was based only on the intensity level of physical movement, meaning that the study may have overestimated the time participants spent in sedentary behaviour. Additionally, there was no information about participants' income and characteristics of the neighbourhoods where they live, which limits the study's ability to account for social and environmental factors, including participants' risk of one-year cardiac events and deaths. Also, hospital discharge information about whether patients were sent home, referred to rehabilitation, or referred to other care centres such as skilled nursing facilities, was not collected. This limited the study's ability to fully assess whether the patients' settings had an impact on their recovery.

"This study provides further support for a 'sit less, move more' strategy and — important for patients recently hospitalised for acute coronary syndrome who may have barriers to more intense exercise — found that increasing light-intensity activities by 30 minutes a day was related to dramatic reductions in the risk of a cardiac event within the next year," said Bethany Barone Gibbs, Ph.D., FAHA, a professor and chair of the department of epidemiology and biostatistics at the School of Public Health at West Virginia University in Morgantown, West Virginia, and immediate past chair of the American Heart Association's Physical Activity Committee.

"This study found that replacing sedentary time with light-intensity activities, like tidying up the house or strolling at a slow pace, was nearly as beneficial as moderate-to-vigorous intensity physical activities, like biking or doing aerobics. In addition, replacing just 30 minutes of sedentary behaviour with any intensity of physical activity more than halved the risk of having a cardiac event over the one-year follow-up," she said. "These findings suggest sitting less and doing anything else — like taking a walk, cooking, playing with your dog, or gardening — will help you stay healthier."