With over 300 joints, your body was made for movement. Although the rising tide of technology has created an amazing number of ways to share information, it has also increased the number of hours you remain seated each day. It's likely by now most understand sitting glued to your desk all day increases your risk of illness and early death.
Unfortunately, the average U.S. adult spends nine to 12 hours each day sitting,1,2 and a 60-minute workout cannot counteract the effects of this level of inactivity.3 Sitting is not inherently dangerous. The danger is in the amount of time you spend sitting. Brief periods of sitting are natural, whereas long periods can seriously impact your health and shorten your life.
Exercise Likely Not Enough to Offset Damage Done by Sitting All Day
A recent study in the Annals of Internal Medicine4 demonstrated that sitting for prolonged periods of time can indeed be deadly. Even those who exercised heavily when they were not at the office experienced a significantly increased risk of death when seated for eight hours a day.
During the study, the team evaluated 8,000 Americans over the age of 45 for a four-year period. Participants wore accelerometers to track their movements. The researchers found those who moved more were healthier overall. However, they also found a correlation between death rates of participants and how many hours they spent seated during the day. In other words, there was a relationship between the time spent seated and the risk of early mortality from any cause.5
Although the American Heart Association encourages sitting less and moving more, the guideline maybe too simplistic. Keith Diaz, certified exercise physiologist and lead author of the study at Columbia University, believes this is like telling someone to exercise without telling them how.6
Instead, guidelines should be precise, such as those by the U.S. Centers for Disease Control and Prevention, which recommends moderate-intensity aerobic exercise for 2.5 hours every week, plus strengthening activities two or more times a week. Diaz says:7 “We need similar guidelines for sitting. We think a more specific guideline could read something like, ‘For every 30 consecutive minutes of sitting, stand up and move or walk for five minutes at a brisk pace to reduce the health risks from sitting.’”
Although previous studies found daily sitting time to average between nine and 10 hours per day,8 data analysis from this study found an average of 12.3 hours of sedentary behavior for an average 16-hour waking day.
As total sedentary time increased, so did early death by any cause, regardless of the participants’ age, sex, race, body mass index or exercise habits.9 The results indicated those who sat in stretches of less than 30 minutes had a 55 percent lower risk of death than those who sat for more than 30 minutes at a stretch.
What Happens When You Sit for Long Periods of Time?
Sitting for long periods of time takes a toll on your body. Dr. James Levine, codirector of the Mayo Clinic/Arizona State University Obesity Initiative, and author of the book “Get Up! Why Your Chair Is Killing You and What You Can Do About It,” has dedicated a good part of his career to investigating the health effects of sitting.
His investigations demonstrate when you sit for long periods of time a number of molecular cascades are initiated. Ninety seconds after standing, muscular and cellular systems processing blood sugar, triglycerides and cholesterol are activated, simply by carrying your own body weight.
These cellular mechanisms are also responsible for pushing fuel into your cells, and when done regularly, may radically reduce your risk of diabetes and obesity. In other words, while your joints make movement easier, your body enjoys benefits even at the molecular level.
Although many recommend standing for 10 minutes of every hour of sitting, I believe this is the bare minimum and far from ideal. It seems far wiser to strive to sit as little as possible each day. Here are some things that may go wrong when you're parked in front of your desk all day long.10
In the seated position, muscles burn less fat and blood flows more sluggishly. Prolonged sitting has been linked to hypertension, and research data demonstrates women who sit for 10 hours a day may have a significantly greater risk of developing heart disease than those who sit for five hours or less.11
Research has demonstrated those who sit for long periods of time are twice as likely to have diabetes or heart disease, compared to those who sit the least.12 Sitting eight hours a day has been associated with a 90 percent increased risk of Type 2 diabetes.13
Sitting may increase your risk of colon, breast, lung,14 uterine and endometrial cancers. This increased risk may be due to an excess insulin production encouraging cell growth, or a reduction in protection from antioxidants regular movement boosts in your body.
Another risk may be related to weight gain and associated biochemical changes, such as alterations in hormones, metabolic dysfunction, leptin dysfunction and inflammation.
Sitting after eating slows digestion and compresses your abdominal contents. This in turn may lead to cramping, bloating, heartburn and constipation, as well as dysbiosis in your gastrointestinal tract.
This is a condition created by microbial imbalances. According to Microbial Ecology in Health and Disease,15 there's growing evidence it is associated with pathogenesis of intestinal and extra-intestinal disorders, including inflammatory bowel disease, irritable bowel syndrome and celiac disease, as well as allergies, metabolic syndrome, cardiovascular disease and obesity.
Your brain function slows when your body is sedentary for too long. Your brain will get less fresh blood and oxygen, which are needed to trigger the release of brain- and mood-enhancing chemicals.
Many commonly sit with head and neck forward working at a computer or cradling a phone. This leads to strain of your cervical vertebra, with permanent imbalances, which can lead to neck strain, sore shoulders and back. Sitting also increases pressure on your spine and the toll is worse if you are sitting hunched over. It is estimated 40 percent of people with back pain have spent long hours at their computer each day.
Standing requires your core muscles to be engaged, which often go unused when you sit in a slouched position. Your hips may also suffer, becoming tight with limited range of motion as they are rarely extended. This may lead to decreased mobility and falls in the elderly. Sitting weakens your gluteal muscles, affecting your stability and the power of your stride.
Sitting leads to poor circulation in your legs, causing swelling in your ankles, varicose veinsand blood clots known as deep vein thrombosis. Walking, running and engaging in other weight-bearing activities increases your bone density and reduces your risk for osteoporosis and bone fractures.