Sedentary lifestyle



Sedentary lifestyle is a lifestyle type, in which one is physically inactive and does little or no physical movement and/or exercise. A person living a sedentary lifestyle is often sitting or lying down while engaged in an activity like socializing, watching TV, playing video games, reading or using a mobile phone or computer for much of the day. A sedentary lifestyle contributes to poor health quality, diseases as well as many preventable causes of death.

Sitting time is a common measure of a sedentary lifestyle. A global review representing 47% of the global adult population found that the average person sits down for 4.7 to 6.5 hours a day with the average going up every year. The CDC found that 25.3% of all American adults are physically inactive.

Screen time is a term for the amount of time a person spends looking at a screen such as a television, computer monitor, or mobile device. Excessive screen time is linked to negative health consequences.

Definition
Sedentary behavior is not the same as physical inactivity: sedentary behavior is defined as "any waking behavior characterized by an energy expenditure less than or equal to 1.5 metabolic equivalents (METs), while in a sitting, reclining or lying posture". Spending most waking hours sitting does not necessarily mean that an individual is sedentary, though sitting and lying down most frequently are sedentary behaviors. Esmonde-White defines a sedentary lifestyle as a lifestyle that involves "longer than six hours a day" of sedentary behavior.

Health effects
Effects of a sedentary work life or lifestyle can be either direct or indirect. One of the most prominent direct effect of a sedentary lifestyle is an increased BMI leading to obesity. A lack of physical activity is one of the leading causes of preventable death worldwide.

At least 300,000 premature deaths, and $90 billion in direct healthcare costs are caused by obesity and sedentary lifestyle per year in the US alone. The risk is higher among those that sit still more than five hours per day. It is shown to be a risk factor on its own independent of hard exercise and BMI. People that sit still more than four hours per day have a 40 percent higher risk than those that sit fewer than four hours per day. However, those that exercise at least four hours per week are as healthy as those that sit fewer than four hours per day.

Indirectly, an increased BMI due to a sedentary lifestyle can lead to decreased productivity and increased absenteeism from necessary activities like work.

A sedentary lifestyle contributes to or can be a risk factor for:


 * Anxiety
 * Cardiovascular disease
 * Migraines
 * Breast cancer
 * Colon cancer
 * Computer vision syndrome (only from excessive electronic use)
 * Depression
 * Diabetes
 * Gout
 * High blood pressure
 * Lipid disorders
 * Skin problems such as hair loss
 * Mortality in adults
 * Obesity
 * Osteoporosis
 * Scoliosis
 * Spinal disc herniation (low back pain)
 * Weight gain

Brain function
Extended periods of sitting reduce overall blood circulation. This diminished blood flow leads to reduced oxygen delivery to the brain (cerebral hypoxia), impairing cognitive functions such as concentration and alertness. The brain relies heavily on a continuous supply of oxygen and glucose for optimal performance; decreased circulation hampers this supply, resulting in cognitive sluggishness and decreased mental sharpness.

Neck and shoulders
Sitting, particularly with poor posture, often involves craning the neck forward to look at screens or documents. Such forward head posture puts excessive strain on the cervical vertebrae, leading to muscle tension and pain in the neck and shoulders. Over time, this can cause the cervical vertebrae to become misaligned permanently, leading to chronic neck pain and potential nerve impingement.

Upper body and back
The intervertebral discs, which act as cushions between the vertebrae, are subjected to constant pressure when sitting for prolonged periods. This compression can lead to disc degeneration and herniation. Additionally, collagen, a primary structural protein in tendons and ligaments, tends to harden when not regularly stretched and mobilized, which leads to decreased flexibility and increased risk of injury in the back.

Heart disease
Physical inactivity reduces the efficiency of the cardiovascular system. Sluggish blood flow allows for the accumulation of fatty acids and lipids in the blood vessels. These deposits can adhere to the vessel walls, forming plaques (atherosclerosis), which eventually narrow the arteries and restrict blood flow. This condition increases the risk of coronary artery disease and heart attacks as the heart struggles to receive adequate oxygen and nutrients.

One study found that interrupting sitting with 20 minutes of light-intensity walking each hour significantly reduced systolic and diastolic blood pressure in healthy participants or 3 minutes of light intensity walking every 30 minutes.

Overproductive pancreas
A sedentary lifestyle contributes to decreased muscle activity, which affects glucose metabolism. Reduced muscle activity leads to lower insulin sensitivity, prompting the pancreas to produce more insulin to maintain normal blood glucose levels (metabolic syndrome). Chronic overproduction of insulin can exhaust the pancreas and contribute to insulin resistance, a precursor to type 2 diabetes.

Leg problems
Prolonged sitting impedes venous return from the legs to the heart, leading to venous stasis (slow blood flow in the veins). This can cause fluid to pool in the lower extremities, resulting in swelling (edema) and varicose veins. Also, sluggish blood flow increases the risk of clot formation, potentially leading to deep vein thrombosis (DVT), a condition where blood clots form in the deep veins, which can travel to the lungs and cause a life-threatening pulmonary embolism.

Mitigation
Adults and children spend long amounts of time sitting in a workplace or at a school, which is why interventions have been focused in these two areas. Mass media campaigns might also be able to reduce the amount of time spent sitting or lying down and positively affect the intention to be active physically.

Recent innovations in AI technology have led to the development of exercise prescription systems designed to reduce sedentary behavior. These systems deliver personalized exercise plans by analyzing individual health metrics, potentially decreasing the prevalence of a sedentary lifestyle and its associated health risks.

In urban spaces
Some evidence has been found of a negative association between exposure to an existing urban motorway and moderate to vigorous physical activity. The proportion of physically active individuals was higher in high- versus low-walkability neighborhoods. Rising rates of being overweight, obesity, and physical inactivity in China's rapidly growing cities and urban populations have been due to urban development practices and policies.

In a work environment
Occupational sedentary behaviour accounts for a significant proportion of sitting time for many adults. Some workplaces have implemented exercise classes at lunch, walking challenges among coworkers, or allowing employees to stand rather than sit at their desks during work. Workplace interventions such as alternative activity workstations, sit-stand desks, and promotion of stair use are among measures implemented to counter the harms of a sedentary workplace.

Research
A 2018 Cochrane review concluded that "At present there is low‐quality evidence that sit‐stand desks may reduce sitting at work in the first year of their use. However, the effects are likely to reduce with time. There is generally insufficient evidence to draw conclusions about such effects for other types of interventions and for the effectiveness of reducing workplace sitting over periods longer than one year."

An intervention to encourage office workers to stand and move reduced their sitting time by 22 minutes after 1 year; the effect was 3-times greater when the intervention included a sit-to-stand desk. The intervention also led to small improvements in stress, wellbeing and vigor.

In education
The majority of time children are in a classroom, they are seated (60% of the time). Children who regularly engage in physical activity are more likely to become healthy adults; children benefit both physically and mentally when they replace sedentary behavior with active behavior. Despite this knowledge and due in part to an increase in sedentary behaviors, children have 8 fewer hours of free play each week than they did 20 years ago.

Several studies have examined the effects of adding height-adjustable standing desks to classrooms, which have reduced the time spent sitting. However, associating the reduction in sitting with health effects is challenging. In one study conducted on Australian school children, known as the Transform-Us! study, interventions reduced the amount of time children spent sitting in the classroom, which was associated with lower body mass index and waist circumference. The interventions used in the study included stand-up desks and easels, the use of timers, and sport and circus equipment in the classroom. Teachers also made lessons more active, and added breaks to lessons to promote active time. In the US, another intervention for children is promoting the use of active transportation to and from school, such as through the Safe Routes to School program.

History
Over the last hundred years, there has been a large shift from manual labor jobs (e.g. farming, manufacturing, building) to office jobs which is due to many contributing factors including globalization, outsourcing of jobs and technological advances (specifically internet and computers). In 1960, there was a decline of jobs requiring moderate physical activity from 50% to 20%, and one in two Americans had a physically demanding job, while in 2011 this ratio was one in five. From 1990 to 2016, there was a decrease of about one third in manual labor jobs/employment. In 2008, the United States American National Health Interview Survey found that 36% of adults were inactive, and 59% of adult respondents never participated in vigorous physical activity lasting more than 10 minutes per week. According to a 2018 study, office based workers typically spend 70-85% sitting. In the US population, prevalence of sitting watching television or videos at least 2 h/d was high in 2015-2016 (ranging from 59% to 65%); the estimated prevalence of computer use outside school or work for at least 1 h/d increased from 2001 to 2016 (from 43% to 56% for children, from 53% to 57% among adolescents, and from 29% to 50% for adults); and estimated total sitting time increased from 2007 to 2016 (from 7.0 to 8.2 h/d among adolescents and from 5.5 to 6.4 h/d among adults).