Cardiologists have found that sedentary behavior like sitting too much is associated with increased amounts of calcium deposits in heart arteries, which in turn is associated with a higher risk of heart attack.
Researchers at UT Southwestern have previously shown that excessive sitting is associated with reduced cardiorespiratory fitness and a higher risk of heart disease.
The latest research – part of UT Southwestern’s Dallas Heart Study – points to a likely mechanism by which sitting leads to heart disease.
“This is one of the first studies to show that sitting time is associated with early markers of atherosclerosis buildup in the heart,” said senior author Dr. Amit Khera.
“Each additional hour of daily sedentary time is associated with a 12 percent higher likelihood of coronary artery calcification.”
The researchers concluded that reducing daily “sitting time” by even 1 to 2 hours per day could have a significant and positive impact on future cardiovascular health, and called for additional studies into novel interventions to reduce sedentary behaviors.
For the many individuals with a desk job that requires them to sit for large portions of the day, they suggested taking frequent breaks.
“Try a one to five minute break every hour. Stand up. Walk up a flight of stairs. All of this helps in a small way. Then get in your strenuous exercise in the evening as well,” said Dr. Julia Kozlitina.
In some individuals, cholesterol builds up inside the walls of the arteries supplying blood to the heart in mounds called cholesterol plaques. Over time, calcium accumulates in these plaques.
The amount of coronary artery calcium can be measured through CT scanning and directly correlates with the amount of cholesterol plaque, as well as with heart attack risk.
In this study, the researchers asked some 2,000 participants in the Dallas Heart Study to wear a device that measured their activity levels for a week.
Participants spent an average of 5.1 hours sitting per day and an average of 29 minutes in moderate to vigorous physical activity each day.
“We observed a significant association between increased sedentary time and coronary artery calcium,” said Dr. Khera, who holds the 2013 Dallas Heart Ball Chair in Hypertension and Heart Disease.
“These associations were independent of exercise, traditional cardiovascular disease risk factors such as diabetes and high blood pressure, and socioeconomic factors.
The current study appears online in the Journal of the American College of Cardiology: Cardiovascular Imaging.