A study published in the Journal of the American College of Cardiology (JACC) highlights the risks associated with spending too much time sitting, reclining, or lying down. The research found that spending over 10.5 hours a day being sedentary could significantly increase the risk of developing heart problems, such as heart failure, and even lead to a higher chance of death due to cardiovascular diseases (CVD). This link was evident even in people who met the recommended levels of physical activity.
Dr. Shaan Khurshid, a cardiologist at Massachusetts General Hospital and one of the study’s lead authors, emphasized the importance of reducing sedentary behavior to improve heart health. He explained that spending too much time sitting or lying down is harmful, even for otherwise active individuals.
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Experts have long known that regular exercise is essential for maintaining a healthy heart. Current guidelines recommend at least 150 minutes of moderate-to-vigorous physical activity each week. However, this study points out that exercise makes up only a small portion of daily activity. The majority of the day, for many people, is spent in sedentary activities, which are not directly addressed in the guidelines.
The study sought to determine the amount of sedentary time that poses the highest risk for heart health. It also examined how sitting time and physical activity together influence conditions like atrial fibrillation, heart failure, heart attacks, and cardiovascular mortality.
The study analyzed data from 89,530 participants in the UK Biobank, with an average age of 62 years and women outnumbering men. They wore wrist devices that recorded their movements over seven days. On average, participants spent about 9.4 hours a day being sedentary.
Over the course of eight years, researchers noted the following:
- 3,638 participants (4.9%) developed atrial fibrillation.
- 1,854 (2.1%) experienced heart failure.
- 1,610 (1.84%) suffered a heart attack.
- 846 (0.94%) died from cardiovascular causes.
The risks associated with sedentary time varied depending on the condition. For Atrial Fibrillation and heart attacks, the risk increased steadily as sedentary time rose. However, the risk remained relatively low for heart failure and cardiovascular mortality until sedentary time exceeded 10.6 hours a day, when the risk grew significantly.
Even among those who met the recommended levels of physical activity, prolonged sedentary time continued to increase the risk of heart failure and cardiovascular death.
Dr. Khurshid suggested that public health efforts should emphasize reducing sedentary behavior as part of maintaining good heart health. He noted that keeping daily sedentary time below 10.6 hours could be a realistic goal for many people.
Dr. Charles Eaton from Brown University added that wearable devices, such as accelerometers, have revealed how much people underestimate their sedentary time and overestimate their exercise. He explained that replacing just 30 minutes of sitting each day with physical activity, even light activity, could reduce the risk of heart failure and cardiovascular death. For example, moderate-to-vigorous exercise lowered the risk of heart failure by 15% and cardiovascular death by 10%, while light activity reduced these risks by 6% and 9%, respectively.
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While the findings are significant, the study had some limitations. It could not determine why or where participants spent their sedentary time, such as at work, which might affect cardiovascular risk differently. Additionally, wrist-worn devices might inaccurately classify standing time as sedentary. The study also couldn’t directly measure the benefits of replacing sitting time with other activities.
Despite these limitations, Dr. Harlan Krumholz from Yale School of Medicine stated that the study adds to the growing evidence linking sedentary behavior to heart health. He stressed that encouraging people to move more is critical for improving overall health.
In summary, staying active and reducing sedentary time are key steps to better heart health, regardless of how much exercise one gets.