While You Were Sitting…
…your body was deteriorating. Today we discuss the health hazards of sitting.
In 1995, Sandra Bullock and Bill Pullman starred in the romantic comedy, While You Were Sleeping. We typically think not much is going on with our bodies while we are asleep, but during sleep our bodies are quite active physiologically.
The same is true when we sit. The body may be at rest when we sit, but physiologically many things are happening to our bodies, but none of them are good. This is in contrast to the healthy physiologic processes that happen when we are asleep. In fact, the body is performing some rather miraculous work when we are asleep. The same is not true when we sit.
Sleep is restorative and regenerative. Sitting is destructive and degenerative.
A Body in Motion
In physics we learned that a body in motion stays in motion…unless an external force is applied to it. This is Newton’s first of three laws of motion paraphrased. Much is the same with the human body. A human body that is active is likely to remain more active longer. If we consider the human body a machine, then it is the only machine that breaks down faster from not being used than from being used. It is the only machine that rusts faster from a lack of use. Let that thought sink in.
We are meant to be moving … at least more than most of us do move.
The Hazards of Sitting
In How Much Do You Do It? and Staying Active is NEAT! we discussed the harms of sitting in broad terms. Today we review what actually happens when we sit. Here’s what happens when we sit.
Metabolism
When we sit blood flow slows down and our muscle burn fewer calories increasing the risk of obesity. Sedentary muscles do not respond to insulin very well. Insulin is a hormone produced in the pancreas that drives sugar from the bloodstream into the cells where it is used for energy. Sedentary individuals require more insulin to drive sugar into the muscles and other tissues. They become insulin resistant. Over time the pancreas burns out, blood sugar climbs, and type 2 diabetes develops.
Just one day of excessive sitting is enough to cause a decline in insulin responsiveness. Thus, daily activity is important.
Cardiovascular
High blood pressure and elevated cholesterol have been linked to prolong sitting. And, those least active are two times more likely to have heart disease than those who are the most active.
Cancer Risk
In Lower Your Cancer Risk with Exercise we discussed that the risk of 13 cancers can be reduced with moderate to vigorous exercise. Excessive sitting increases the risk of:
- lung cancer by 54%.
- uterine cancer by 66%.
- colon cancer by 20%.
Increased cancer risk is thought to be related to high blood sugar and insulin levels. Cancers feed on sugar. Also, there are changes in sex hormones and hormones that regulate appetite and satiety that occur when we are sedentary that contribute to weight gain and increase the risk of inflammation all of which contributes to higher cancer risk.
Gut Dysbiosis
One of the worse things you can do after eating is … sitting. Yet, that is the “activity” that most of us do after eating. Dysbiosis refers to microbial imbalance. We have more bacteria and other microorganisms in our guts than we do cells in the body. These microbes actually are beneficial to our health. Read our article, Gut Microbiome: How it Keeps You Healthy.
Sitting disrupts the delicate balance of the microbiome. First, when you sit the abdominal organs are compressed slowing digestion. For some this can lead to bloating, cramping, constipation, and heartburn. All of this can cause dysbiosis. Activity promotes a healthier gut microbiome. This mai be related to the positive effects of exercise on extra-intestinal disorders that affect the gut microbiome.
The gut microbiome is affected by both intestinal and extra-intestinal factors. Intestinal disorders that alter the gut microbiome include irritable bowel disease and inflammatory bowel disease, and celiac disease. Extra-intestinal diseases include allergies, asthma, metabolic syndrome (high blood pressure, lipid abnormalities, glucose intolerance, and obesity), and cardiovascular disease. Exercise is beneficial and helps in the management of these extra-intestinal disorders.
Brain alterations
When we are sedentary brain function slows down. Less oxygen and nutrients are being delivered to the brain. The brain is only 2% of our body weight but utilizes 60% of the glucose (calories) at rest as the whole body and uses three times as much oxygen as muscles do. In fact, the brain consumes 25% of the body’s oxygen.
Perhaps the best way to improve brain function is to simply … move … and deliver more blood flow, oxygen, and nutrients to the amazing computer that sits in the skull. More blood flow improves the release of neurotransmitters that affect our moods and cognitive function.
Posture
Posture provides clues to one’s overall health. Good posture and good health go hand in hand. Sitting puts a strain on posture. Sitting leads to neck and shoulder problems. It put excess load on the lower back especially the disks. Disks expand and contract when we move which creates a pumping action allowing better delivery of blood (oxygen and nutrients) to the spine.
Sitting also increases the curve in the thoracic spine (mid back) which can restrict lung expansion further impeding the absorption and delivery of oxygen to the body
Musculoskeletal Changes
Sitting leads to other maladaptive changes to the musculoskeletal system beyond the spine. Sitting decreases hip flexibility and mobility and in the elderly this contributes to falls. When we sit the abdominal muscles relax. And, if sit the better portion of the day the abdominal and gluteal muscles weaken affecting our core stability which affects directly and indirectly the entire musculoskeletal system.
Sitting contributes to loss of bone density leading to osteopenia and osteoporosis increasing the risk of fragility fractures.
Circulation Problems
Prolonged and repeated sitting reduces circulation in the legs, causes swelling, varicose veins, and increases the risk of blood clots or deep venous thrombosis or DVT.
Sitting Statistics
Here are some of the hazards of sitting.
- Americans sit 13 hours a day with 7.5 hours at work.
- Sitting 3 hours plus a day contributes to 3.8% of all-cause death or 433,000 deaths a year.
- People who watch 7 hours or more of TV a day have a 61% greater risk of dying than those who watch less than one hour a day.
Don’t become a sitting statistic. Move around. Stand as much as you can while doing desk work. Take the a stairs rather than the elevators. Park some distance from a building so you have a longer walk. If you watch TV use the commercials as 2-3 minute sitting breaks and walk or do calisthenics. Be sure to stretch your hip flexors if you do have to sit and maintain the lordosis or curve in your lower back when sitting.
Exercise is important, but you cannot exercise out the harmful effects of 3-4 hours or more of sitting. See our articles How Much Do You Do It? and Staying Active is NEAT!
If you do not like to exercise then keep in mind this. The less you sit, the less you need to exercise. You do not need to exercise to move.
Article update 12/26/22. Originally published 6/19/16.
