A sedentary lifestyle involves little physical activity and is associated with health risks. It is defined as activities requiring 1.5 METs or less and can include sitting or lying down while socializing, watching TV, or using technology. Approximately 31% of the global population leads an insufficiently active lifestyle, contributing to 3.2 million deaths annually. A sedentary lifestyle can increase the risks of obesity, cardiovascular disease, diabetes, osteoporosis, and certain cancers by reducing bone and vascular health and altering metabolism. It reduces lipoprotein lipase activity, decreasing fat breakdown and increasing triglycerides. It also increases bone resorption without improving formation, reducing bone mineral density over time.

1. Physiological Consequences of
Sedentary lifestyle
By: Dr. Ravi Dutt

2. Learning objectives
• Meaning of sedentary lifestyle
• Consequences of sedentary lifestyle
• Health risks associated
• How to lead an active lifestyle

3. • A sedentary lifestyle is a type of lifestyle involving little or no physical
activity, as opposed to an active lifestyle.
• A person living a sedentary lifestyle is often sitting or lying down while
engaged in an activity like socializing, watching television, playing video
games, reading or using a mobile phone/computer for much of the day.
• Sedentary behavior is defined as any waking behavior such as sitting or
leaning with an energy expenditure of 1.5 metabolic equivalent task (MET)
or less.
• This definition, proposed by the Sedentary Behavior Research Network in
2012, is currently the most widely used definition of sedentary behavior.

4. • MET is defined as the ratio of work metabolic rate to the standard
resting metabolic rate (RMR).
• One MET is the RMR or energy cost for a person at rest.
• When classified quantitatively based on their intensities, physical
activities can be classified into :
• 1.0–1.5 METs (sedentary behavior),
• 1.6–2.9 METs (light intensity),
• 3–5.9 (moderate intensity),
• and ≥6 METs (vigorous intensity)

6. Epidemiology
• Approximately 31% of the global population aged ≥15 years engages
in insufficient physical activity, and it is known to contribute to the
death of approximately 3.2 million people every year.
• It is well known that insufficient physical activity has a detrimental
effect on health.
• Physical inactivity is the fourth leading risk factor for global mortality,
accounting for 6% of global mortality.

7. Causes of Physical Inactivity and Sedentary Lifestyles
• A poor participation in physical activity is speculated to be influenced
by multiple factors.
• Some environmental factors include air pollution ,traffic congestion,
shortage of parks or pedestrian walkways, and a lack of sports or
leisure facilities.
• Television viewing, video viewing, and cell phone usage are positively
correlated with an increasingly sedentary lifestyle.
• Most physical activity-related education in clinical practice is focused
on improving the physical activity levels, with less emphasis on
lowering the sedentary behavior.

8. Health effects of sedentary lifestyle
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 sedentary lifestyle and lack of physical activity can contribute to or be a
risk factor for:
• Cardiovasular diseases, Hypertension, Stroke, Dyslipedemia
• Type-2 diabetes
• Osteoporosis
• Certain cancers like colon and breast cancers
• Depression and anxiety

9. Physiological consequences of sedentary lifestyle
 Recent evidence suggests that sedentary behaviour has a direct influence on
metabolism, bone mineral content, and vascular health.
 Effect of sedentary behaviour on Metabolism :
The deleterious effects of sedentary behaviour on metabolic health appear to be
at least partially mediated by changes in lipoprotein lipase (LPL) activity.
LPL is an enzyme that facilitates the uptake of free fatty acids into skeletal muscle
and adipose tissue
. Low levels of LPL are associated with increased circulating triglyceride levels,
decreased HDL cholesterol, and an increased risk of cardiovascular disease .
LPL activity appears to be reduced in response to both acute and chronic
sedentary behaviour.

10. Effect of sedentary behaviour on Bone health
• Another well-documented deleterious effect of sedentary behaviour is a
reduction in bone mineral density .
• Both humans and animals experience dramatic reductions in bone mass following
long periods of time spent in orbit, and significant decreases have also been
reported in individuals following spinal cord injuries and during long-term bed
rest
• It is thought that the relationship between sedentary behaviour and reduction in
bone mass is mediated by changes in the balance between bone resorption and
deposition.
• Various studies suggest that sedentary behaviour leads to a rapid increase in
bone resorption without concomitant changes in bone formation, eventually
resulting in reduced bone mineral content and increased risk of osteoporosis.
• Further, it appears that vigorous physical activity alone is not enough to prevent
these changes in bone metabolism; less sedentary behaviour may also be
required.

11. Effect of sedentary behaviour on Vascular health
• Although it has yet to receive the same attention as bone mineral
density or metabolic health, limited evidence indicates that sedentary
behaviour may also have deleterious effects on vascular health .
• Various studies have found that complete bed rest resulted in
decreased endothelium-dependent vasodilation and increased
endothelial cell damage .
• Interestingly, they also found that these deleterious changes in
vascular function were prevented by a combination of aerobic and
resistance exercise, suggesting that a common mechanism may link
vascular health to both sedentary behaviour and vigorous activity.

12. Ways to be more active at work
 Get up from your chair and move around at least once an hour
 Stand when you are talking on the phone
 Take the stairs instead of the elevator
 Use your break or part of your lunch hour to walk around the
building
 Stand up and walk to a colleague's office instead of sending an email
 Have "walking" or standing meetings with co-workers instead of
sitting in a conference room

13. Ways to be more active around the house
 Gardening and household work are all physical work
 Keep moving while you watch TV. Lift hand weights, do some gentle yoga stretches, or
pedal an exercise bike. Instead of using the TV remote, get up and change the channels
yourself.
 Work out at home with a workout video (on your TV or on Mobile)
 Go for a walk in your neighbourhood. It can be more fun if you walk your dog, walk your
kids to school, or walk with a friend.
 Stand up when talking on the phone
 Get some exercise equipment for your home. Treadmills is very good or Less expensive
equipment such as yoga balls, exercise mats, stretch bands, and hand weights can help
you get a workout at home too.

14. References
1.Sedentary lifestyle. In: Wikipedia . 2021. Available from:
https://en.wikipedia.org/w/index.php?title=Sedentary_lifestyle&oldid=1050341052
2.Park JH, Moon JH, Kim HJ, Kong MH, Oh YH. Sedentary Lifestyle: Overview of Updated Evidence of
Potential Health Risks. Korean J Fam Med. 2020 Nov;41(6):365–73.
3. Tremblay MS, Colley RC, Saunders TJ, Healy GN, Owen N. Physiological and health implications of
a sedentary lifestyle. Appl Physiol Nutr Metab Physiol Appl Nutr Metab. 2010 Dec;35(6):725–40.
4.Health Risks of an Inactive Lifestyle . National Library of Medicine; Available from:
https://medlineplus.gov/healthrisksofaninactivelifestyle.html