Why sitting for too long increases risk of heart disease

A sedentary lifestyle, characterised by prolonged periods of sitting or inactivity, has long been linked to various health risks, including an increased likelihood of heart disease.

New research, published in the Journal of the American College of Cardiology, highlights that this risk persists even among individuals who regularly engage in physical activity outside their daily routines.

The study, which analysed data from nearly 90,000 participants, offers valuable insights into the relationship between sedentary time and cardiovascular diseases, such as heart attacks, strokes, and heart failure.

A notable finding was that individuals who sat for more than 10.6 hours per day had a greater risk of developing cardiovascular issues. While not an absolute threshold, Dr Ezimamaka Ajufo suggests that aiming to limit sitting time to less than 10.6 hours daily is a reasonable target for public health guidelines.

The impact of prolonged sitting

Prolonged sitting adversely affects health for several reasons. When we sit for extended periods, our muscles are not actively engaged, reducing their ability to regulate essential processes such as blood sugar and fat metabolism.

Muscles require regular movement to function optimally, and without this stimulation, the body’s capacity to manage these processes diminishes.

While the study is observational—demonstrating an association but not causation—it aligns with previous research on the harmful effects of sedentary behaviour.

Dr Keith Diaz, on the other hand, explains that regular movement is necessary to stimulate muscles and maintain healthy blood sugar and lipid levels. Incorporating short movement breaks throughout the day can significantly enhance how the body manages these functions.

Practical solutions for reducing sedentary time

For those working in offices or spending long hours commuting, the risk of sitting for over 10 hours daily is high. Standing desks have gained popularity, but Dr Diaz cautions that standing still does not provide the muscle movement required to counteract the effects of sitting. Instead, he recommends activities such as walking or using a treadmill desk during the workday.

Dr Diaz also advises taking short walking breaks every 30 minutes to an hour or moving around after completing tasks to keep muscles engaged. These small adjustments can help mitigate the negative effects of extended sitting.

The limits of exercise

The study also revealed that even a vigorous workout at the end of the day cannot entirely counterbalance the harm caused by prolonged sitting.

Dr Ajufo emphasised that while exercise is beneficial for overall health, it cannot fully negate the risks of sedentary behaviour.

"Sometimes we think we can compensate for unhealthy habits with a run or a workout," she noted, but the findings highlight the importance of regular movement throughout the day to reduce the risks associated with sitting.

Dr Diaz, however, reassures that exercise remains a vital component of a healthy lifestyle. "You’re still better off than someone who sat all day and didn’t exercise," he said.

Regular physical activity provides numerous benefits, including improved cardiovascular health, but it should be complemented by efforts to reduce sedentary time.

Promoting a healthier lifestyle

While exercise is essential for good health, avoiding long periods of sitting is equally crucial. Taking movement breaks and reducing overall sedentary time can help mitigate health risks and promote better heart health.

Physical inactivity is a major risk factor for noncommunicable diseases (NCDs) and premature death worldwide.

Conversely, regular physical activity significantly lowers the risk of various health conditions, including:

Cancer: Reduces risk by 8–28%.

Heart disease and stroke: Reduces risk by 19%.

Type 2 diabetes: Reduces risk by 17%.

Mental health issues: Lowers risk of depression and dementia by 28–32%.

According to the World Health Organisation (WHO), a sedentary lifestyle is associated with numerous adverse health outcomes, such as:

Increased Mortality: Inactive individuals face a 20–30% higher risk of premature death compared to active people.

Cardiovascular Disease: Prolonged sedentary behaviour is linked to increased risks of heart disease and stroke.

Cancer: Sedentary lifestyles raise the risk of developing and dying from certain cancers.

Type 2 Diabetes: Inactivity is a significant contributor to type 2 diabetes.

Obesity: Sedentary behaviour is a major factor in obesity and excessive body fat.

Mental Health Issues: Lack of physical activity is associated with higher risks of mental health problems, such as depression.

Musculoskeletal Problems: Inactivity can lead to joint pain (arthralgia) and conditions like osteoporosis.

Reducing sedentary time and incorporating regular movement into daily life are crucial steps towards improving overall health and well-being.