Why you are probably sitting down for too long

Sitting for long periods can have a significant impact on our health. Many people find themselves sitting throughout the day, whether they are at work, commuting, or relaxing at home. This sedentary lifestyle can lead to serious health issues, including cardiovascular disease and type 2 diabetes. A pivotal study conducted by epidemiologist Jeremy Morris in 1953 revealed that London bus drivers had a higher incidence of coronary heart disease compared to their colleagues, the bus conductors. The two groups were similar in age, gender, and income, yet the bus conductors, who were constantly on their feet and climbing the stairs of double-decker buses, enjoyed better heart health. This groundbreaking research highlighted the importance of physical activity in maintaining cardiovascular health. In recent years, particularly since the onset of the Covid-19 pandemic, many individuals have shifted to remote work, which has likely contributed to increased sedentary behavior. The absence of regular movement, such as walking to meetings or taking breaks, has made it easier for people to remain seated for extended periods. By the 1980s, office culture had already begun to change, leading some researchers to humorously suggest that humans were evolving into 'the seated man. ' Prolonged sitting is characterized by a significant reduction in energy expenditure, and common sedentary activities include watching television, playing video games, driving, and desk work. These behaviors are linked to various health risks, including obesity, metabolic syndrome, and premature mortality. Research has shown that the time spent sitting has increased dramatically over the years, prompting experts to recommend strategies to reduce sedentary behavior. It is essential to note that one can engage in regular exercise yet still sit for too long, which poses its own set of risks. Studies indicate that breaking up long periods of sitting with physical activity can help mitigate some of the adverse health effects associated with a sedentary lifestyle. The question arises: why does sitting for extended periods increase the risk of cardiovascular disease? The primary hypothesis revolves around vascular dysfunction. The vascular system plays a crucial role in circulating blood and lymph fluid, which is vital for our immune system. According to Dunstan, a physiologist at Deakin University's Institute for Physical Activity and Nutrition, prolonged sitting leads to reduced muscular activity. When seated, the chair takes on the responsibility of supporting the body, leading to decreased muscle engagement. This lack of activity, combined with lower metabolic demand and the effects of gravity, can result in blood pooling in the legs. The typical seated position, with bent legs, further restricts blood flow. Reduced muscular activity in the legs diminishes blood circulation, which is essential for maintaining healthy blood flow. Studies have shown that prolonged sitting can lead to increased blood pooling in the calves, which can have negative health implications. Earlier this year, my colleagues and I conducted research that suggested it might not be crucial to reach the 10,000 steps daily goal, but certain types of exercise can significantly impact health. It is also important to remember that even small movements can be beneficial. Normal blood flow creates friction, known as arterial shear stress, against the endothelial cells lining blood vessels. This shear stress is essential for maintaining vascular health and homeostasis. However, reduced blood flow diminishes shear stress, leading to the release of substances that cause blood vessels to constrict. This creates a vicious cycle where vasoconstriction further reduces blood flow, resulting in elevated blood pressure, a major risk factor for cardiovascular disease. Dunstan notes that while the underlying mechanisms are still being studied, recent research supports the theory that prolonged sitting can lead to various health issues. Studies involving young, healthy individuals have shown that extended sitting increases blood pooling in the legs and peripheral vascular resistance. Researchers generally agree that sitting uninterrupted for a certain duration likely poses health risks, and prolonged sitting is particularly harmful. The Dutch, known for their love of both exercise and sitting, present an interesting case study. They manage to balance both activities effectively. The musculoskeletal system is also affected by prolonged sitting, which can lead to issues such as lower back pain and poor posture. Additionally, sitting for long periods is associated with increased risk of obesity, diabetes, and other health problems. Dunstan, who specializes in type 2 diabetes research, emphasizes that sedentary behavior can lead to impaired insulin sensitivity and vascular function, both of which contribute to a higher risk of cardiovascular disease and type 2 diabetes. Given these well-documented risks, it is essential to understand why we sit for so long and how we can break this habit. Gardner, a social psychologist at the University of Surrey, suggests that societal norms have encouraged sedentary behavior. As life becomes more efficient, people tend to move less. In a study conducted in 2018, Gardner and his team found that encouraging standing during meetings led to interesting results. Participants felt that standing was inappropriate in formal settings. Some researchers believe that social factors need to change to help people break up their sitting time. Other interventions, such as adjustable desks and sit-stand chairs, can promote movement. Even small actions, like getting up occasionally, can be beneficial. Wearable technology can also play a role in encouraging movement. Devices that track sitting and standing patterns can provide valuable insights and reminders to get up. However, some individuals may become desensitized to these prompts. Ultimately, the idea of breaking up sedentary time by standing is straightforward, but it can be challenging, especially for those with low activity levels. For individuals with mobility constraints, even small movements can be advantageous. While sedentary behavior may seem like an unavoidable aspect of modern life, making small changes to daily routines, such as stretching, fidgeting, or standing up to grab a drink, can help break the cycle of excessive sitting.