Excessive Sedentary Behaviour Risks Cannot Be Altered Even With Exercise, New Study Finds

If you are a desk person by day and a fitness enthusiast by night, health risks of sitting for long hours at a place still cannot be avoided. More time spent sitting, reclining or lying down during the day may increase the risk of cardiovascular disease (CVD) and death. Excessive sedentary behavior, encompassing actions such as sitting or lying down for extended periods, has been linked with an increased risk of heart failure (HF) and cardiovascular (CV) death, reveals research published in JACC, the premier journal of the American College of Cardiology.

This correlation persists even among individuals who engage in the recommended levels of physical activity, highlighting a significant health concern. The study, showcased at the American Heart Association's Scientific Sessions 2024, points out that spending more than approximately 10.5 hours in sedentary activities daily could significantly elevate the likelihood of future HF and CV mortality.

Dr. Shaan Khurshid, MD, MPH, a cardiologist at Massachusetts General Hospital and one of the leading authors of the study, emphasized the importance of reducing time spent in sedentary behaviors to lower cardiovascular risk. "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," he stated. This insight is particularly crucial as it suggests that even physically active individuals are not immune to the adverse effects of prolonged inactivity on heart health.

The research builds upon existing knowledge that insufficient exercise is a known contributor to cardiovascular disease (CVD). Current health guidelines advocate for at least 150 minutes of moderate-to-vigorous physical activity weekly to foster cardiac wellness. However, these guidelines primarily focus on physical activity without addressing the significant portion of the day most people spend being sedentary. This omission is notable given the mounting evidence linking sedentary behavior with increased CVD risk.

The study leveraged data from the UK Biobank, involving 89,530 participants with an average age of 62 years, of which 56.4% were women. Through a wrist-worn triaxial accelerometer, researchers measured participants' movements over a span of seven days, noting an average daily sedentary time of 9.4 hours.

Over an eight-year follow-up period, the study observed that the risk associated with sedentary behavior varied depending on the specific cardiac outcome. Notably, for HF and CV mortality, the risk escalated significantly only after surpassing the daily 10.6-hour mark of sedentary time, indicating a threshold effect for these conditions.

Interestingly, for those adhering to the recommended 150 minutes of moderate-to-vigorous physical activity weekly, the negative impacts of sedentary behavior on AF and MI risks were notably diminished. Yet, the heightened risk for HF and CV mortality remained a concern, underscoring the need for balanced physical activity and reduced sedentary time for optimal heart health.

"Future guidelines and public health efforts should stress the importance of cutting down on sedentary time," Khurshid advocated. "Avoiding more than 10.6 hours per day may be a realistic minimal target for better heart health."

In support of these findings, Charles Eaton, MD, MS, Director of the Brown University Department of Family Medicine, highlighted the significance of replacing sedentary time with physical activity. He noted the benefits of even modest increases in physical activity, stating, "Replacing just 30 minutes of excessive sitting time each day with any type of physical activity can lower heart health risks." He further elaborated that incorporating moderate-to-vigorous activity could reduce the risk of HF by 15% and CV mortality by 10%, with even light activity offering a 6% reduction in HF risk and a 9% decrease in CV mortality.

However, the study acknowledges several limitations, including challenges in accurately assessing the context of sedentary behavior and the potential for inaccuracies in detecting posture through wrist-worn accelerometers. These factors, along with the potential for confounders and selection bias, suggest a need for further research to fully understand the impact of sedentary behavior on cardiovascular health.

This research presents compelling evidence of the detrimental effects of prolonged sedentary behavior on heart health, even among those who exercise regularly. This underscores the importance of not only engaging in sufficient physical activity but also actively seeking to decrease sedentary time as a means to safeguard against cardiovascular disease and mortality.