Prolonged sitting occupies most of our daily time both at home, office or transport. Human bodies are made for moving around as that is what we did for thousands of years. But rapidly developing technology has led to a sedentary life.
Modernization of the offices and shifting of emphasis from paper to computer has also contributed to this. Office workers generally work in a sitting position for much of the day
However, the data has accumulated over the period has suggested the hazards and adverse health effects of prolonged sitting.
It is estimated that a significant part of the population may spend up to three-fourths of their workday sitting.
With more and more jobs becoming sedentary in nature as compared to earlier, prolonged sitting threatens the health of the majority of the population.
More than 60% of the mid-age population in developed countries is now overweight or obese and sitting poses an additional health risk.
Prolonged sitting increases the risk factor for type 2 diabetes, obesity, heart disease, bone and joint disorders, some types of cancer, and premature death
On the contrary, there is great number of health benefits when we stand up, sit less and move more.
Thus for maintaining of good health of an individual or population, the following measures should be taken
- Reduce sitting time
- Promote physical activity
This is crucial for the future health of aging populations.
What is Sedentary Behavior?
Sedentary behavior is defined as any behavior characterized by an energy expenditure of fewer than 1.5 METs while in a sitting or reclining posture.
MET stands for the metabolic equivalent of task and estimates the rate of energy consumption in a given activity.
Different types of activities depending on MET are
- Light intensity
- <3 MET
- Examples
- Deskwork- 1.5
- Walking slowly- 2
- Moderate intensity
- 3 to 6 METS
- Examples
- Normal walking [3]
- Yoga [3.3]
- Vigorous-intensity activities
- Greater than or equal to 6
- Examples
- Bicycle riding
- Jogging
- Swimming
- Jumping
Harmful Effects of Prolonged Sitting
Sitting for long periods of time is associated with a number of health concerns.
Commonly known effects of sitting are obesity, increased blood pressure, diabetes, abnormal lipid levels and excess fat around the waist.
It is estimated that for each two-hour increment in sitting time, the risk of obesity increases by 5 percent and that of diabetes by 7 percent.
However, there is a whole spectrum of effects that continuous sitting causes.
Deconditioning or Exercise Intolerance
Deconditioning is a kind of exercise intolerance in where one finds it more difficult to perform physical tasks than usual.
This happens due to reduced muscle mass, decreased vascularization and cellular changes like decreased mitochondrial activity and reduction in oxidative enzymes.
Increased production of inflammatory mediators (e.g., tumor necrosis factor and interleukin-6) also play a role.
When a sedentary person exercises, the heart is not able to pump sufficient blood leading to an oxygen deficit, depletion of nutrients and accumulation of lactic acid contributing to muscle fatigue.
Moreover, these persons may have impeded blood flow that prevents blood vessels from dilating. There is also a lesser production of nitric oxide [vasodilator].
It is also suggested that smaller mitochondrial size and less oxidative enzymes also contribute to heart failure.
Lung Function
Prolonged slumping or kyphosis may impede the movement of the diaphragm. Sedentary behavior leads to lesser lung volume during inspiration. So the muscle contraction is nt effective. In fact, workers’ inability to breathe deeply may cause airway issues.
Stiffness and loss of elasticity also contribute to restrictive airway disease.
Musculoskeletal Problems
Stiffness results from decreased muscle elasticity and muscle wasting caused by prolonged sitting.
Sarcomeres are the functional units of striated muscles and bring out the change in the muscle length wich causes joint movements. Over a period, excessive sitting results in shortening of the sarcomere, therefore affecting its
There is also a decrease in the quantity of hyaluronic acid in joint fluid. This along with decrease blood supply contributes to the joint stiffness.
This could be worsened by a lack of exercise leading to joint contractures.
Osteoarthritis and joint inflammation may also be associated.
The presence of obesity can further worsen osteoarthritis by mechanical loading and production of adipokines [ pro-inflammatory and catabolic cytokines] that destroy joints and cartilage.
Sitting is also a risk factor for developing osteoporosis. Hormones that lead to healthy bone formation like osteocalcin, insulin growth factors, and growth hormone are reduced.
Post-menopausal women are especially at increased risk for less bone formation after loss of estrogen hormone.
Increased Risk of Thrombosis [Blood clot] formation
Prolonged sitting may lead to blood clots in lower limbs because there is decreased nitric acid production and more fibrinogen levels
Decreased nitric oxide decreases vasodilation and fibrinogen favors coagulation. Chronic inflammation due to decreased oxygen levels may contribute.
Premature Aging and Chronic Diseases
A sedentary lifestyle is said to cause premature aging. There are many factors for this namely obesity, diabetes, cardiovascular diseases, high blood pressure, and metabolic syndrome.
Prolonged sitting may promote cell aging, rapid cell death, and inflammation. These three along with other factors contribute to premature aging and chronic diseases.
Poor sleep quality
Poor sleep quality is another issue. Poor sleep further contributes to early fatigue.
Weight gain can cause obstructive sleep apnea that promotes daytime drowsiness and fatigue.
Also, sedentary behaviors may depress the production of melatonin, a neurotransmitter associated with sleep quality and wakefulness.
Moreover, fatigue and impaired sleep increase the sympathetic response, elevating resting heart rate and blood pressure too.
How to Counter and Prevent Adverse Effects of Sitting
The basic tenet is to reduce sitting time and increase activity as a lifestyle measure. Everything revolves around these two basics.
Take Frequent Breaks
We can reduce sitting time at home at will while the workplace sitting is part of the job and therefore not entirely avoidable.
But frequent interruptions can contribute a lot. It is advisable to take a break every 30 minutes to 60 minutes.
Every time when we get up and move, the muscles work and its beneficial effects through minimal add over the day.
Simply Stand
We can shift our activities from sitting to standing. There are a lot of leisure activities we do while sitting and we can shift all of them to standing and sitting mixture. For example, watching television and taking on the phone can easily be shifte to standing position.
If you work at a desk, buy a standing desk or improvise with a high table or counter.
Where whole time standing is not feasible, a sitting/standing mix of postures can be tried.
Walk More
Find the opportunity to walk more. A meeting with colleagues, wholly or part-time can be done walking than sitting in a conference room.
Using stairs instead of the lift, parking at the farthest end, walking instead of riding to nearby places are few examples.
Exercise
About 60 minutes of moderately intense physical activity a day is claimed to counter the effects of countered the effects of too much sitting
Exercise helps by following effects
- Exercise may improve glucose uptake in cells
- Exercise prevents cell aging by reducing anti-inflammatory cytokines
- Exercise may also increase skeletal muscle interleukin-6 [helps in muscle repair]
- Improves oxygenation in the lower extremities
- Increases nitric oxide levels, and reduces fibrinogen
- Helps better bone-building by
- Stimulates calcium absorption
- Stimulates the production of osteocalcin, which promotes bone mineralization
- Staying active may improve osteoarthritis
- Improve blood supply
- Increase the production of synovial fluid in the joints
- Exercise has positive influences on cognitive abilities
- Improves sleep quality improves with exercise.
Therefore increasing participation in physical activity is the principle for preventing major chronic diseases and obesity.
Author’s Note
All said and done, sitting is an essential part of human postures, social gatherings, and work. But because it is prolonged in the modern lifestyle, we need to take countermeasures.
So sit for a lesser duration at a stretch, take frequent breaks and include exercise in your daily routine.
References
- Thorp AA, Healy GN, Winkler E, Clark BK, Gardiner PA, Owen N, Dunstan DW. Prolonged sedentary time and physical activity in workplace and non-work contexts: a cross-sectional study of office, customer service and call centre employees. Int J Behav Nutr Phy. 2012;9:128. doi: 10.1186/1479-5868-9-128.
- Tremblay MS, Colley RC, Saunders TJ, Healy GN, Owen N. Physiological and health implications of a sedentary lifestyle. Appl Physiol Nutr Metab. 2010;35:725–40. doi: 10.1139/H10-079.
- Warburton DE, Nicol CW, Bredin SS. Health benefits of physical activity: the evidence. Can Med Assoc J. 2006;174:801–9. doi: 10.1503/cmaj.051351.
- Roelofs A, Straker L. The experience of musculoskeletal discomfort amongst bank tellers who just sit, just stand or sit and stand at work. Ergonomics SA. 2002;14:11–29.
- Healy GN, Dunstan DW, Salmon J et al. Breaks in sedentary time: beneficial associations with metabolic risk. Diabetes Care 2008;31:661–6.
- Hamilton M, Healy G, Dunstan D et al. Too little exercise and too much sitting: Inactivity physiology and the need for new recommendations on sedentary behaviour. Current Cardiovascular Risk Reports 2008;2:292–8.
- Ambrose, K., Golightly, Y. (2015). Physical exercise as non-pharmacological treatment of chronic pain: Why and when. Best Practice & Research Clinical Rheumatology, 29, 120-130. doi:10.1016/j.berh.2015.04.022
- Asvold, B., Midthjell, K., Krokstad, S., Rangul, V., Bauman, A. (2017). Prolonged sitting may increase diabetes risk in physically inactive individuals: An 11 year follow-up of the HUNT Study, Norway. Diabetologia, 60, 830-835. doi:10.1007/s00125-016-4193-z
