Sedentary Lifestyle: The Sitting Disease

Thanks to technology, we have a surplus of information and resources available at our fingertips. Televisions, smartphones, and video games let us immerse ourselves in entertainment. We can connect with nearly anyone in the entire world. It is technology that has made us able to travel and transport ourselves to work through cars and airplanes. In the workplace, machines have replaced jobs that require human labour, so that we can do less.

But all of this has come at a cost. We sit or stand still as we watch television or use the computer and other electronic devices. We sit when we drive to work, and sit again if we work an office job; and we sit again when we read, study, or write.

Globally, 1 in 4 adults are not active enough (1). According to the World Health Organization, insufficient physical activity is 1 of the 10 leading risk factors for death worldwide, and is a key risk factor for noncommunicable diseases (NCDs) such as cardiovascular diseases, cancer, and diabetes (2).

This growing trend has been called the “sitting disease,” and for good reason. Our sedentary lifestyle is slowly destroying our health and our lives.

What is a sedentary lifestyle?

A sedentary lifestyle is often defined as a type of lifestyle with an excessive amount of sitting, or where the individual does not receive regular amounts of physical activity.

These definitions have led to some confusion since people who fulfill the recommended 30 minutes a day of exercise may feel that they are not living a sedentary lifestyle. However, people who sit or work at an office job for even 4 hours a day are still at an increased risk of developing health problems such as diabetes and cardiovascular disease.

Some people may not be meeting the physical activity guidelines of moderate and vigorous physical activity, but they may still be performing light activity throughout the day such as standing or doing yard work. These people who do a lot of non-exercise activities may not be at as high a risk of developing problems associated with living a sedentary lifestyle and instead may be at a reduced risk.

The act of sitting alone does not mean that you are living a sedentary lifestyle, though it is closely related. If you are sitting while expending energy, such as when canoeing, performing chair-based exercise or pushing yourself in a wheelchair, then you are not being sedentary. Sitting while using an electronic device or doing office work, however, is considered sedentary behaviour.

A sedentary lifestyle can be defined as a lifestyle where you exhibit sedentary behaviour for an extended amount of time. The term “inactive” can then be used to describe someone who is performing insufficient amounts of moderate to intense physical activity. This distinction is important since it means that people who are performing the recommended amount of moderate exercise but spend over 4 hours a day sitting are still at a higher risk of developing health complications.

More specifically, sedentary behaviour refers to activities that require very low energy expenditure, or under or equal to 1.5 metabolic equivalents.

What is MET (metabolic equivalent for task)?

A metabolic equivalent (MET) is a type of unit used to measure the intensity of physical activity. One MET is equal to 3.5 mL of oxygen per kg of body weight per minute. “Taking the oxygen energy equivalent of 5 kcal/L consumed, this corresponds to 0.0175 kcal/minute/kg (3.5 mL/min/k x 0.005 kcal/mL)” (3) of energy expenditure.

Multiples of MET are used to estimate the oxygen cost, or the energy expenditure, of an activity. For instance, an activity that has a MET of 1.4 requires 1.4 times the resting metabolism, and an activity that has 3 METS requires three times the resting metabolism. This offers a practical, convenient method of measuring the energy cost of activities.

What are the MET values for different activities?

Light activities are activities that are under 3 METS or have an energy expenditure of 50 to 200 kCals per hour (4). Activities equal to or under 1.5 METS (or 110 kcals/hour) include sitting, lying or sleeping, and desk work. Other light activities include standing, housework, fishing, horseback riding, and playing an instrument, including the piano, accordion, cello, flute, and violin.

Moderate activities are from 3 to 4 METS or 200 to 350 kCals per hour. They include bicycling, boating, swimming at 0.25 mph, walking, and yard work.

Intense or strenuous activity are those over 4 METS or 250 kcals/hour. They include dance, racquet sports, running, swimming, shovelling, speed walking, climbing hills, skating, and skiing.

Sedentary behaviour can be more accurately described as any waking behaviour characterized by an energy expenditure of ≤1.5 METs while in a sitting or reclining posture. By this definition, sleeping is not considered sedentary behaviour, though both undersleeping and oversleeping pose their own health risks.

What are the consequences of a sedentary lifestyle?

One of the reasons that prolonged sitting may increase the risk of developing health complications is due to the enzyme lipoprotein lipase (LPL). This enzyme plays a critical role in breaking down fat and determining whether it is stored or burned for energy. LPL activity has been known to decrease when sitting, and increase when standing.

Sitting or lying on fat cells can cause them to produce more triglycerides (a type of fat or lipid in the blood). High levels of triglycerides have been shown to contribute to the hardening of the arteries or thickening of the artery walls, which increases the risk of stroke, cardiovascular disease, and high blood pressure.

Gravity and the lack of movement can prevent proper circulation and can cause fluid to build up in the lower legs. This fluid can later migrate to the muscles and tissues of the neck when you lie down to sleep, and can cause the throat to swell, which restricts breathing.

Your posture while sitting, which curves the spine and puts strain on the spinal cord, can also prevent your lungs from getting enough space to expand fully. This also restricts breathing, and prevents oxygen from being distributed throughout your body. Restricted oxygen and blood circulation affects memory and concentration. It can increase feelings of depression and anxiety.

Our bodies are made to move. Muscles and bones need regular physical activity to maintain strength. Our lymphatic system cannot move on its own. It requires the contractions of skeletal muscles to constrict the vessels to push the fluid forward.

Without physical activity, we begin to lose lean muscle tissue and bone density. Inactivity or prolonged sitting causes the body’s metabolism to slow and prevents our bodies from using insulin effectively. This can in turn cause blood sugars to rise and can be a contributing factor to developing diabetes.

A sedentary lifestyle is also associated with an increased risk of metabolic syndrome and certain types of cancer. “Recent evidence suggests that having a high level of sedentary behaviour negatively impacts health independent of other factors including body weight, diet and physical activity” (5).

Inactivity, or sedentary behaviour, is one of the leading risk factors for death worldwide, and yet it is also one of the most easily reversible. Studies have suggested that inactivity is responsible for more annual deaths than smoking, and is twice as deadly as obesity.

How do I combat the effects of a sedentary lifestyle?

To combat the effects of a sedentary lifestyle, you need to incorporate more physical activity into your routine.

If you work an office job or spend a lot of time in front of a computer screen, you can invest in a standing desk, a treadmill desk, or a bike desk. Be cautious when using a standing desk. While standing does use more energy than sitting, standing in one place for an extended amount of time can also put strain on the legs and can result in poor circulation. You can also try sitting on a balance ball chair. You want to try to incorporate as much movement as possible.

If you are unable to invest in a treadmill desk or bike desk, you can still reduce sitting time by taking frequent, short breaks that include standing, walking around, or stretching for as little as 5 minutes every 30 minutes to an hour. It is also recommended to limit the amount of recreational time spent watching TV or videos, playing on the computer, or playing video games.

You can also multitask while doing these generally stationary activities by marching in place or using a treadmill, indoor bike, dumbbells, or other indoor exercise equipment. If you are watching television, you can also tidy the room at the same time; and if you are playing a video game, you can try more activity-promoting games such as dancing or other interactive sports games.

Instead of watching television or playing games, you may want to try more physically active recreational activities or hobbies such as swimming, dancing, gardening, golfing, hiking or exploring the outdoors, or plein air painting. Even cooking, washing your car or cleaning your house can provide a necessary break from sitting.

Takeaway

Automobiles, workplace machinery, smartphones, computers, and televisions all have their place, but they shouldn’t replace our ability to exercise and move around. As these technologies and conveniences have become more commonplace, we have spent more and more time sitting, until it has become not only a disease, but an addiction.

Activity is crucial to our well being. All around us the world is in a constant flux of growth and change; and we, too, are made to join this state of movement. Our body is designed to move, heal, and grow. Many of us put off exercise or any physical activity because we are “too busy” working and “making a future” for ourselves. Instead, we should be placing physical activity on the top of our to-do list. It is a crucial and worthwhile investment toward our health, our future, and our lives.