This Is What Happens to Your Body When You Sit All Day

It's time to invest in that standing desk!

If you're one of the millions of Americans with an office job and have yet to jump aboard the standing desk bandwagon, then you're likely used to spending the bulk of your day sitting down. And, as you might expect, spending eight-plus hours moving little more than your fingers as you type doesn't exactly do wonders for your overall health—especially over the course of a decades-spanning career. But what exactly makes all those hours slumped in your desk chair so harmful? From muscle pain to breathing problems, read on to discover what happens to your body when you sit all day.

The muscles in your shoulders weaken.

No matter how much you try to keep yourself from slouching at work, long hours spent sitting inevitably end up the same way—with your back bent forward and your shoulder blades slumped into a slouch that forces them to tip forward and curl inward. So, as you can imagine, this added strain on the shoulders can create quite a bit of pain, especially for those sitting day-in and day-out for months, years, or even decades.

Over time, if this slouching finds its way into your life outside the office, it can actually completely alter how your shoulder blades move and function, according to an oft-cited 2008 study published in the American Journal of Epidemiology. In fact, after long periods spent sitting, participants in the study found that it was harder to lift their arms above their heads—a motion that becomes more difficult for the muscles in your shoulder after they become accustomed to a slouching position.

And, as it turns out, this slouching also has a profound effect on your spine. Maintaining bad posture while you sit for hours at a time (even if it's only a few times a week) can create wear and tear on your disks and joints, too.

The muscles in your back and legs weaken, too.

After just an hour or so of sitting without a break, your postural muscles (the muscles along your back and legs that work to maintain your posture) begin to lose their firing power, or ability to engage properly. And, according to Lara Heimann, a physical therapist and creator of LYT Yoga, unless you ensure that these muscles are being actively used and tightened while you're sitting, this could lead to a noticeable decline in posture after just a short period of time.

"As they 'dial down' their firing power, your muscles will give less resting support…so you will consequently sag into the seat," says Heimann. "Unless you bring conscious awareness to your seated position and [keep] the core postural muscles slightly engaged, you will sink more into your joints and let gravitational forces take over."

Blood flow decreases.

Your postural muscles' decreased firing power also accounts for decreased blood flow in your lower extremities. According to a 2011 study published in the British Medical Journal, sitting for long periods of time can cause sluggish blood flow, especially in the legs. This can cause blood clots to form; when those clots make their way to your lungs, they can cause a pulmonary embolism.

You feel intense lower back pain.

After just a few hours of sitting, your sacrum bone (the bone just above the coccyx, or tailbone) tends to shift position, stiffen, and cause discomfort. "The sacrum bone that sits in between pelvic bones gets jammed up into the vertebrae of the low back and at the sacroiliac joints," explains LeTrinh Hoang, D.O.

Since sitting for long periods of time can also make the postural muscles around the sacrum weaker, this combination of symptoms can lead to inflammation of the sacroiliac joint. The inflammation causes pain to radiate up the entire back, down the legs, or out from the hips. In fact, according to a 2015 review of research published in PLOS Onethere is a significant association between the amount of time a person spends seated and the intensity of their lower back pain.

You can develop arthritis of the back.

As your postural muscles weaken and your sacrum bone shifts, the joints in your hips also begin to suffer. When your body begins to grow accustomed to sitting for hours at a time, it relaxes the hip flexors—the muscles in charge of lifting the knee and bringing the thigh towards the abdomen—causing them to weaken and shorten, according to Hoang. This shortening of the hip flexors often leads to a bigger issue that occurs in chronic sitters: arthritis of the back.

Since the hip flexors—which control the movement of the pelvis and, subsequently, the lower back—are constantly strained by sitting, this increases pressure on the facet joints of the lower spine. According to a 2013 review of research published in Nature Reviews Rheumatology, over time, degradation of the facet joints can contribute to arthritis and lower back pain.

Your lungs produce less oxygen.

Your lungs have less space to expand as you breathe when you're sitting down. They're not functioning at their normal capacity and are no longer providing a healthy amount of oxygen to the rest of your body. This can result in symptoms like lightheadedness, confusion, rapid heart rate, and shortness of breath.

Your abdomen is compressed, leading to digestive issues.

Along with the lungs, your abdomen is also compressed when you remain seated at your desk for hours at a time. And, since this compression of the abdomen includes parts of your gastrointestinal tract, you're likely to experience digestive issues like bloating and gas, cramps, heartburn, and discomfort after eating, according to a 2015 study published in Microbial Ecology in Health and Disease.

Your risk for Alzheimer's increases.

As you already know, sitting all day can drastically reduce blood flow in all areas of the body—and your brain isn't immune to this change. Along with this decrease in blood flow, spending a large portion of your life sitting down can reduce the production of new neurons, limit plasticity, and increase inflammation, according to a 2018 study published in PLOS One. This decreased activity in the brain is responsible for a loss of thickness in the medial temporal lobe—the part of the brain responsible for memory, among other things. This is why, according to the study, 13 percent of Alzheimer's cases have been linked directly to sedentary lifestyles.

In addition to this heightened risk of Alzheimer's, your sitting habits can also negatively affect your cognitive performance in other ways—including reduced processing speed and ability to plan and organize, according to a 2017 study published in the British Journal of Sports Medicine.

Your risk for diabetes increases.

After just one day of prolonged sitting, those inactive muscles in your body have a harder time responding to insulin, according to a 2011 study published in the journal Metabolism. Insulin is the hormone produced by your pancreas to help break down glucose for energy. So when your body doesn't effectively break down glucose, your risk for diabetes skyrockets. Ready to stop sitting and make your workday a little healthier? Check out these 40 Workplace Habits You Need to Drop by 40.

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Ashley Moor
Ashley hails from Dayton, Ohio, and has more than six years of experience in print and digital media. Read more
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