A sedentary lifestyle is associated with harmful health outcomes. It has been reported that 1/3rd of the population ≥15 years engages in insufficient physical activities across the globe, causing adverse health outcomes. Limited physical activity includes extended sitting at work, in cars, workplaces, schools, homes, and public places which restrict the ways of human movement and muscle activities. This shift from a physically active life to reduced physical activities has increased the risk of developing various health conditions such as obesity, hypertension, deep vein thrombosis, type – 2 diabetes, osteoporosis (weakening of bones), cancer, and muscle and skin disorders resulting in increased mortality. These disorders are associated with unhealthy lifestyles which can be prevented.
Conceptualizing Sedentary Lifestyle
The word "Sedentary" is derived from the Latin word "Seder" meaning "to sit" therefore sedentary behavior is characterized by practices that are linked with low energy expenditure. Low energy expenditure of ≤1.5 metabolic equivalent task (MET) is considered sedentary behavior. MET is used to evaluate energy expenditure during activities. Running has a value of 8 METs and brisk walking has a value of 3-4 METs. Even in those individuals who maintain moderate to vigorous physical activity (MVPA) the risk of disease is there if they also engage in prolonged sedentary activities. This concept has been referred to as the "Active Couch Potato" phenomenon.
Causes of Sedentary Lifestyle
The most common causes are prolonged television viewing, video viewing, cell phone usage, and increased car driving which is directly correlated with an increased sedentary lifestyle. Some environmental factors include traffic jamming, air pollution, shortage of parks or pedestrian sidewalks, and a lack of sports amenities.
Sedentary Lifestyle Diseases
1. Cardiovascular (CV) health risks
Numerous studies have documented that a sedentary lifestyle and physical inactivity are one of the major risk factors for increased cardiovascular (CV) risk. In one study, 82% of participants reported >10 hours/week of car driving and 23 hours/ week of watching TV. In 64% of participants increased cardiovascular risk was observed.
2. Diabetes
In adolescents, there is a 3-fold increased risk of metabolic syndrome in those with at least 5 h/day of TV and computer screen time compared with those with ≤1 hour. In another study conducted on adults, a 14% increase in type – diabetes with each 2 h/day increase in TV viewing time, and a 7 % increase in type-2 diabetes with each 2 h/day increase in sitting at work. This is due to reduced physical activity due to increased TV screen times and unhealthy eating patterns. The biological mechanism which can explain the impact of the total daily sedentary time on CVD and DM risk is prolonged sitting which can affect the activity of muscle glucose transporter proteins.
3. Obesity
Obesity is generally characterized by the accumulation of excess body fat to such an extent that it can show adverse health outcomes on the individual's health. Studies show an increase in waist circumference by 3.1 cm with a 10% increase in sedentary time. Obesity can lead to insulin resistance leading to type 2 diabetes. A sedentary lifestyle has been shown to increase the prevalence of obesity among men from 14% to 25 % and in women from 11% to 24% for those who averaged ≤5 h/week of TV viewing versus that averaging > 21 h/week.
4. Hypertension (HTN)
A sedentary lifestyle affects blood pressure by changing cardiac output and total peripheral vascular resistance. An extended sedentary time reduces metabolic needs, and decreases insulin sensitivity but increases oxidative stress (which can cause the breakdown of tissues and DNA damage) and stimulates the series of inflammatory events. A study reported a direct association between sedentary behavior and a high risk of HTN (Hazard ratio: 1.48).
5. Dyslipidemia
Sedentary behaviors can cause elevated blood triglyceride levels, reduced HDL-cholesterol levels (good cholesterol), and reduced insulin sensitivity. The harmful effects of sedentary behavior on metabolic health somewhat seem to be facilitated by changes in lipoprotein lipase (LPL) enzyme 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 triglyceride levels, decreased HDL cholesterol, and an increased risk of cardiovascular disease.
6. Bone health
A sedentary lifestyle can also lead to a reduction in bone mineral density. The changes in the balance between bone resorption and deposition are related to sedentary behavior causing a reduction in bone mass.
7. Musculoskeletal (skin & muscle) diseases
Muscles require regular exercise to be strong and a sedentary lifestyle can reduce muscle strength. Alteration in body posture and chronic keen pain are some of the musculoskeletal effects caused by a sedentary lifestyle. A prolonged sedentary time was correlated with chronic knee pain. A sedentary time of>10 hours/day is considerably correlated with chronic knee pain. Some skin problems due to a sedentary lifestyle include a change in skin color and fat deposits around the eye folds.
8. Cancer
A sedentary lifestyle can increase the risk of breast cancer in women, prostate cancer in women, and colon cancer. High levels of TV and (or) video watching are associated with an increased risk of colon cancer for men and women and endometrial cancer in women. The women who spent ≥7 h/day sitting had an increased risk of endometrial cancer versus those who were sitting <3 h/day.
9. Depression
Mentally passive sedentary practices such as television viewing, sitting, listening to music, and talking while sitting are positively correlated with depression risks. Sedentary behaviors might increase depression risks by blocking direct communication with people and lowering socialization, thereby reducing the engagement in physical activities that help to prevent and treat depression.
Tips to reduce a sedentary lifestyle
At Workplace
- Use the staircase instead of the elevator/escalator
- Use breaks for short walks
- Stand and walk for 1-2 minutes every 30 minutes during the day
During leisure time
- Reduce the screen time for TV, laptops, and mobiles
- Screen media exposure for children younger than 2 years is not advised
- Take bouts of physical activity every 60 minutes to reduce prolonged sedentary