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.[6][7][8][specify]
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.[9][5]
Sedentary behavior is not the same asphysical inactivity: sedentary behavior is defined as "any waking behavior characterized by anenergy expenditure less than or equal to 1.5metabolic equivalents (METs), while in a sitting, reclining or lying posture".[10][11] Spending most waking hours sitting does not necessarily mean that an individual is sedentary,[3] though sitting and lying down most frequently are sedentary behaviors.[11]Esmonde-White defines asedentary lifestyle as a lifestyle that involves "longer than six hours a day" of sedentary behavior.[12]
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 increasedbody mass index (BMI) leading toobesity.[13] In 2006,Lawrence D. Frank co-authored a highly-cited (over 1,900 citations) article:Many Pathways from Land Use to Health.[14] They determined that a 5% increase in a community'swalkability index was associated with a 32.1% increase in time spent walking or biking and a .23-point reduction in BMI.[15]
A country-level study examining the global cost of disease and its associated risk factors identified obesity as a top-seven risk factor associated with attributable death and a top-eight risk factor associated with attributable disease burden. Obesity was a top-three risk factor for high-income countries.[16][17]
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.[18] The risk is higher among those that sit still more thanfive hours per day. It is shown to be a risk factor on its own independent of hard exercise andBMI. People that sit still more thanfour hours per day have a40 percent higher risk than those that sit fewer thanfour hours per day. However, those that exercise at leastfour hours per week are as healthy as those that sit fewer thanfour hours per day.[19][20]
Indirectly, an increased BMI due to a sedentary lifestyle can lead to decreased productivity and increasedabsenteeism from necessary activities like work.[21]
A sedentary lifestyle contributes to or can be a risk factor for:
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.
Sitting, particularly withpoor posture, often involves craning the neck forward to look at screens or documents. Suchforward head posture puts excessive strain on thecervical vertebrae, leading tomuscle 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 potentialnerve impingement.
Theintervertebral discs, which act as cushions between the vertebrae, are subjected to constant pressure when sitting for prolonged periods.[39] This compression can lead todisc degeneration andherniation. Additionally,collagen, a primary structural protein intendons andligaments, tends to harden when not regularly stretched and mobilized, which leads to decreasedflexibility and increased risk of injury in the back.
Physical inactivity reduces the efficiency of the cardiovascular system. Sluggish blood flow allows for the accumulation offatty acids andlipids in theblood 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 ofcoronary artery disease andheart 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 diastolicblood pressure in healthy participants or 3 minutes of light intensity walking every 30 minutes.[40]
Prolonged sitting impedesvenous return from the legs to the heart, leading tovenous stasis (slow blood flow in the veins). This can cause fluid to pool in thelower extremities, resulting in swelling (edema) andvaricose veins. Also, sluggish blood flow increases the risk ofclot formation, potentially leading todeep vein thrombosis (DVT), a condition where blood clots form in the deep veins, which can travel to thelungs and cause a life-threateningpulmonary embolism.
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.[3]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.[42][43]
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.[44]
Some evidence has been found of a negative association between exposure to an existing urbanmotorway and moderate to vigorous physical activity.[45] The proportion of physically active individuals was higher in high- versus low-walkability neighborhoods.[46] Rising rates of being overweight, obesity, and physical inactivity inChina's rapidly growing cities and urban populations have been due tourban development practices and policies.[47]
Occupational sedentary behaviour accounts for a significant proportion of sitting time for many adults.[48] 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,[49] sit-stand desks, and promotion of stair use are among measures implemented to counter the harms of a sedentary workplace.[50]
A 2018Cochrane 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."[51]
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.[52][53]
The majority of time children are in a classroom, they are seated (60% of the time).[3] Children who regularly engage inphysical activity are more likely to become healthy adults; children benefit both physically and mentally when they replace sedentary behavior with active behavior.[54] Despite this knowledge and due in part to an increase in sedentary behaviors, as of 2018 children have 8 fewer hours of free play each week than they did 20 years before.[55]
Several studies have examined the effects of adding height-adjustablestanding 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 lowerbody mass index andwaist circumference. The interventions used in the study included stand-up desks andeasels, 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.[3] In the US, another intervention for children is promoting the use ofactive transportation to and from school, such as through theSafe Routes to School program.[56]
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 andtechnological 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.[57] From 1990 to 2016, there was a decrease of about one third in manual labor jobs/employment.[58] 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.[59]
According to a 2018 study, office based workers typically spend 70–85% sitting.[60] 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).[61]
Wiecha JL, Sobol AM, Peterson KE, Gortmaker SL (2001). "Household television access: associations with screen time, reading, and homework among youth".Ambulatory Pediatrics.1 (5):244–251.doi:10.1367/1539-4409(2001)001<0244:HTAAWS>2.0.CO;2.PMID11888409.
Laurson KR, Eisenmann JC, Welk GJ, Wickel EE, Gentile DA, Walsh DA (August 2008). "Combined influence of physical activity and screen time recommendations on childhood overweight".The Journal of Pediatrics.153 (2):209–214.doi:10.1016/j.jpeds.2008.02.042.PMID18534231.
Domingues-Montanari S (April 2017). "Clinical and psychological effects of excessive screen time on children".Journal of Paediatrics and Child Health.53 (4):333–338.doi:10.1111/jpc.13462.PMID28168778.
^Lopez AD, Mathers CD, Ezzati M, Jamison DT, Murray CJ (May 2006). "Global and regional burden of disease and risk factors, 2001: systematic analysis of population health data".Lancet.367 (9524):1747–1757.doi:10.1016/S0140-6736(06)68770-9.PMID16731270.
^Manson JE, Skerrett PJ, Greenland P, VanItallie TB (February 2004). "The escalating pandemics of obesity and sedentary lifestyle. A call to action for clinicians".Archives of Internal Medicine.164 (3):249–258.doi:10.1001/archinte.164.3.249.PMID14769621.
^Dunstan DW, Owen N (March 2012). "New exercise prescription: don't just sit there: stand up and move more, more often".Archives of Internal Medicine.172 (6):500–501.doi:10.1001/archinternmed.2012.209.PMID22450937.
^Daniel M. Landers."The Influence of Exercise on Mental Health".President's Council on Physical Fitness and Sports. Retrieved5 February 2010.The research literature suggests that for many variables there is now ample evidence that a definite relationship exists between exercise and improved mental health. This is particularly evident in the case of a reduction of anxiety and depression.
^Biswas A, Oh PI, Faulkner GE, Bajaj RR, Silver MA, Mitchell MS, Alter DA (January 2015). "Sedentary time and its association with risk for disease incidence, mortality, and hospitalization in adults: a systematic review and meta-analysis".Annals of Internal Medicine.162 (2):123–132.doi:10.7326/M14-1651.PMID25599350.
^Kraemer J (March 1995). "Natural course and prognosis of intervertebral disc diseases. International Society for the Study of the Lumbar Spine Seattle, Washington, June 1994".Spine.20 (6):635–639.doi:10.1097/00007632-199503150-00001.PMID7604337.
^Day K, Alfonzo M, Chen Y, Guo Z, Lee KK (May 2013). "Overweight, obesity, and inactivity and urban design in rapidly growing Chinese cities".Health & Place.21:29–38.doi:10.1016/j.healthplace.2012.12.009.PMID23416231.
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