You’ve probably already heard that sitting too much is bad. To be even more precise: Prolonged sitting is considered the new smoking, with just as dangerous health implications. The average derriere-time for a U.S. adult is eight hours a day—but many of us sit for even longer, adding a few bonus couch potato hours in after a long day at the office desk. But what does prolonged sitting actually do to us? Here are five things that can happen when you park it all day, every day.
1. Heart disease
According to a science advisory from the American Heart Association, being sedentary is not just defined as a lack of exercise. Even if you do exercise, sedentary behaviors are a potentially independent risk factor for heart disease and stroke. Here’s what happens: Muscles burn less fat and blood flow slows down during a long sit, giving fatty acids a better chance to clog the heart. Sedentariness has been linked to high blood pressure and elevated cholesterol.
Taken to an extreme, people who sit the most are more than twice as likely to have cardiovascular disease than those who sit the least. Even more alarming, excessive sitting may cause an increased risk of developing diabetes, impaired insulin sensitivity and an overall higher risk of death from any cause.
2. Decreased mobility
Chronic sitting causes muscles to shorten and contract. This has a big impact on the hip flexors, which become short and tight after sitting all day, limiting our range of motion. According to several studies, decreased hip mobility is a main reason elderly people tend to fall.
A constant seated position also harms your back—especially if your posture is under par. Movement causes the soft discs between vertebrae to expand, absorb fresh blood, and soak up nutrients. But sitting causes the discs to contract unevenly and collagen to harden around tendons and ligaments. In general, binge sitting leads to inflexible hips and spine, setting us up for reduced mobility and chronic pain.
3. Leg disorders
Another hazard of sitting for long periods: It can cause blood to pool in the legs, leading to varicose veins or more gravely, deep vein thrombosis. Deep vein thrombosis is a blood clot that if detached, can cut off the flow of blood to other parts of the body such as your lungs, causing a pulmonary embolism and other medical emergencies, including death.
4. Brain function
Even the mildest exercise pumps fresh blood and oxygen through the brain and triggers a cascade of all sorts of brain- and mood-enhancing chemicals. In contrast when we don’t move, everything slows down, including cognition. Exercise is good for the heart and the brain. The converse is also true: Sedentary behavior, which decreases oxygen flow to the brain, has negative ramifications for the brain’s aging process.
One recent study found that inactivity affects the brain by significantly affecting the shape of certain neurons. The neurons became more sensitive and less regulated, hindering the sympathetic nervous system. And a study released in April of this year showed that adults who sat more had thinner medial temporal lobes (MTL), an area of the brain that plays a role in memory and memory loss. This study does not prove that too much sitting causes thinner brain structures, but instead that more hours spent sitting may be predictive of thinner regions. This correlation between sitting and memory formation may be significant for interventions designed to improve brain health in middle-aged or older adults.
An increasing number of studies suggest that prolonged sitting can increase the prevalence of certain types of cancer, including lung, uterine and colon cancers. For the first time, the 2018 Physical Activity Guidelines Advisory Committee Scientific Report stated that sedentary behavior is tied to an increased risk of cancer. And the American Institute for Cancer Research estimates that being physically active, along with staying a healthy weight and eating well, can prevent close to one third of the most common US cancer cases.