According to a recent study published in the journal JACC, spending excessive time sitting, reclining, or lying down during the day could heighten the risk of cardiovascular disease (CVD) and even lead to death. The research highlights that exceeding approximately 10.5 hours of inactivity daily is notably associated with an increased likelihood of heart failure (HF) and cardiovascular-related deaths, even among individuals who meet the recommended exercise guidelines.
A recent study featured in JACC, the primary journal of the American College of Cardiology and presented at the American Heart Association’s Scientific Sessions 2024, suggests that excessive time spent seated or lying down can elevate the risk of cardiovascular disease (CVD) and mortality. It found that engaging in more than about 10.5 hours of sedentary behavior daily is significantly linked to a higher risk of heart failure (HF) and cardiovascular (CV) mortality, even in individuals who exercise as recommended.
“Our study indicates that reducing sedentary time can help decrease cardiovascular risk, with 10.6 hours a day presenting a critical point associated with increased heart failure and cardiovascular mortality,” stated Shaan Khurshid, MD, MPH, a cardiologist from Massachusetts General Hospital and one of the study’s co-senior authors. “Excessive sitting or lying down may be detrimental to heart health, even for those who maintain an active lifestyle.”
Lack of sufficient physical activity is a well-known contributor to cardiovascular disease (CVD). Current guidelines suggest engaging in more than 150 minutes of moderate-to-vigorous physical activity each week to promote heart health. However, the experts involved in the study highlight that exercise is only a small portion of total daily activity, and existing guidelines do not specifically address sedentary behavior, which constitutes a much larger part of daily life and is proven to be linked to CVD risk.
This study aimed to determine the amount of sedentary time that correlates with the highest CVD risk and assess how both sedentary and physically active behaviors collectively influence the chances of developing atrial fibrillation (AF), heart failure (HF), myocardial infarction (MI), and CV mortality.
Involving 89,530 participants from the UK Biobank, the average age was 62 years, with 56.4% being women. Participants provided data through a wrist-worn triaxial accelerometer that tracked movement over a week. On average, individuals were sedentary for 9.4 hours each day.
After an average follow-up period of eight years, 3,638 participants (4.9%) were diagnosed with AF, 1,854 (2.1%) developed HF, 1,610 (1.84%) experienced MI, and 846 (0.94%) died from cardiovascular causes.
The impact of sedentary behavior varied by the health outcomes observed. For AF and MI, the risk consistently increased over time with no significant variations. However, for HF and CV mortality, the risk remained low until sedentary behavior surpassed approximately 10.6 hours a day, when the risk significantly escalated, indicating a “threshold” effect for this behavior.
Among those who followed the recommended 150 minutes of moderate-to-vigorous physical activity weekly, the risks associated with sedentary behavior on AF and MI were notably reduced; however, the elevated risks for HF and CV mortality persisted.
“Going forward, public health initiatives and guidelines should emphasize the importance of reducing sedentary time,” Khurshid remarked. “A feasible target for better heart health may be to limit sedentary hours to no more than 10.6 daily.”
In an editorial accompanying the study, Charles Eaton, MD, MS, Director of the Brown University Department of Family Medicine, highlighted that wrist-mounted accelerometers have shown that self-reported exercise is often overestimated, while sedentary behavior is frequently underestimated.
Eaton suggested that simply replacing 30 minutes of excessive daily sitting with any physical activity can significantly reduce heart health risks. Moderate-to-vigorous activities can lower the heart failure risk by 15% and CV mortality by 10%. Even light physical activity can reduce the risk of heart failure by 6% and CV mortality by 9%.
“This research reinforces the robust relationship between sedentary habits and cardiovascular health,” remarked Harlan M. Krumholz, MD, SM, Harold H. Hines Jr. Professor at Yale School of Medicine and Editor-in-Chief of JACC. “The findings strongly advocate for increasing physical activity to enhance overall health.”
However, the study has several limitations, including the inability to determine specific reasons or locations for prolonged sitting or lying down, such as work conditions, which could affect cardiovascular risk differently. Additionally, wrist-worn accelerometers may inaccurately classify standing time as sedentary time. A longer monitoring duration could yield more accurate insights into activity patterns.
Other limitations encompass potential confounding variables, selection bias, the inability to assess the exact effects of substituting sedentary time with other activities, and discrepancies in data from wrist-worn accelerometers compared to thigh-worn devices.
