Every few days there’s a new study about sitting and heart health. Now, the American College of Cardiology has published the results of a large study about the impact of sedentary behavior on heart health, even for consumers who meet exercise recommendations.
The study of 89,530 individuals found that spending over 10.6 hours per day sitting, reclining, or lying down is associated with significantly increased risks of heart failure and cardiovascular death.
“Our findings support cutting back on sedentary time to reduce cardiovascular risk, with 10.6 hours a day marking a potentially key threshold tied to higher heart failure and cardiovascular mortality,” said Shaan Khurshid, MD, MPH, a cardiologist at the Massachusetts General Hospital and co-senior author of the study. “Too much sitting or lying down can be harmful for heart health, even for those who are active.”
About the study
The study participants had an average age of 62; 56.4% were women. They had an average of 9.4 hours per day of sedentary behavior. They were followed for eight years with the following outcomes:
4.9% developed atrial fibrillation (AF), commonly called a-fib;.
2.1% developed heart failure (HF);
1.84% had myocardial infarction (MI), commonly called heart attack;
0.94% died of cardiovascular (CV) causes.
The researchers found that the risk of heart disease increases steadily with sedentary time and that a threshold effect occurs – creating more significant risk spikes – at 10.6 hours per day.
Meeting 150 minutes/week of moderate-to-vigorous activity reduces AF and MI risks but does not fully offset the HF and CV mortality risks associated with excessive sedentary behavior.
The good news is that replacing 30 minutes of sitting daily with physical activity can:
Reduce HF risk by 15% and CV mortality by 10% with moderate-to-vigorous activity.
Even light activity lowers HF risk by 6% and CV mortality by 9%.
Health implications
“Future guidelines and public health efforts should stress the importance of cutting down on sedentary time,” Khurshid said. “Avoiding more than 10.6 hours per day may be a realistic minimal target for better heart health.”
Guideline Adjustments: Future recommendations should include targets for reducing sedentary time in addition to promoting exercise.
Behavioral Changes: Small, achievable adjustments, like reducing daily sitting time by 30 minutes, can significantly improve heart health.
Limitations in measurement
So how can consumers be sure they’re measuring their activity levels accurately?
In an editorial comment accompanying the study, Charles Eaton, MD, MS, Director of the Brown University Department of Family Medicine, said the use of wearable accelerometers has shown that exercise is significantly over-estimated by self-report and sedentary behavior is under-estimated.
Eaton said that replacing just 30 minutes of excessive sitting time each day with any type of physical activity can lower heart health risks. Adding moderate-to-vigorous activity cut the risk of HF by 15% and CV mortality by 10%, and even light activity made a difference by reducing HF risk by 6% and CV mortality by 9%.
Conclusion
The study, published in the Journal of the American College of Cardiology, underscores the urgent need for public health strategies that not only encourage physical activity but also aim to minimize sedentary behavior, particularly beyond the critical threshold of 10.6 hours/day.