Way back when the human body evolved to hunt big game on the savannah, nary a desk was in sight. In fact, 99.99% of human history never included sedentary office work. Yet, now we ask our bodies to do it all day, most days of the week.
Perhaps there will be a time when humans evolve into a sedentary species that doesn't actually need activity to stay healthy, but that day has yet to come. In the meantime, we'd do well not to fight our nature.
What does nature tell us?
We need to get on our feet and move. It's not just the hand-wringing of health advocates. The proof is in our physiology.
From the ways our cells create energy, to the blood flowing in all the right places, to the structure of our bones, we're made to move and bear the weight of our bodies. This is clear when analyzing the "human machine."
An Animal in Motion
Our large and heavy brain case is perfectly balanced on an s-curved spine that works like a shock absorber while walking and running.
Our arms swing freely to balance and propel us as we move.
We take long strides and use kinetic energy through our large Achilles tendons that appear to be purpose-built to run.
While in motion, our big leg muscles help circulate blood and lymphatic fluid.
Our relatively large lungs (which fill up best when we stand) and a capacity to sweat and cool ourselves better than the animals we once hunted made our prehistoric ancestors unstoppable.
Get this: in warm weather, a human can beat a horse in a long distance race.
Surprising, but true.
Nothing about our physiology indicates we are a sedentary species. Gorillas and chimps, for example, seem built to squat and be still for most of the day, with short spurts of activity. Bears can hibernate for months and emerge lean and ready to take on the world. Sloths simply don't possess the metabolism needed to help them move any faster than a slow crawl. Extended rest is "built in" to their designs, but not ours.
Sitting is only Temporary
When we sit still, our bodies treat it like a temporary rest, even when it's not. Our big cushy glute muscles on our rear ends double as pads for sitting, but they work best holding our bodies up and propelling us forward. We fold up neatly to sit in chairs, but nothing about our body structure or chemical processes indicate that we evolved to be sedentary. Being still helps us catch a break, and that's how your body treats it.
In other words, when you sit all day, your body spends that time preparing as if you are soon going to be very active for a long time. That's a very good thing—if you will being going to chase down your dinner. No, finding a food truck with your smartphone app doesn't count.
The Cascading Effects of Sitting All Day
1. Blood Flow
The movement of your arms and legs has a pump-like effect, circulating blood and lymphatic fluid faster than when you remain still. So, too, does a pounding heart!
Quicker and more complete blood flow is important for all your body systems. When you sit, however,slower blood flow allows for the accumulation of fatty acids in blood vessels, which contributes to heart disease. And, according to medical journal The Lancet, the prevalence of sitting in the western world is a likely explanation for the prevalence of varicose veins.
Lipoprotein lipase is the main enzyme in your body that processes fat in your blood stream. However, when you're sitting, lipoprotein lipase production in your muscles drops by about 90%, which means fat doesn't get used, it gets stored.
Sitting doesn't just use fewer calories: it triggers fat storage.
Perhaps worse, sitting reduces your body's ability to use blood sugar, which can lead to insulin resistance, which leads to obesity and type 2 diabetes.
Bones are living just like the rest of our bodily tissues and are continually undergoing a process known as remodeling. Just as the word implies, we're always breaking our bones down and building them up again. With proper posture and exercise, bones regenerate and help us stay active. With near-constant sitting, however, they aren't triggered to rebuild in appropriate ways, becoming less dense, for example, and prone to breaking.
Beyond bones, our skeletal systems include disks, cartilage, and ligaments that need movement and proper posture to stay healthy and strong. Remember that spinal s-curve I mentioned above? When you sit, that "s" becomes a "c" and compresses one side of the disks that cushion vertebrae, which can lead to pain, inflammation, and other problems like bone spurs.
I've mentioned muscles in each previous section because, naturally, every body system is connected. Muscle movements induce proper blood flow, trigger an efficient metabolism, and support a healthy skeleton. In many ways, muscles exist to create movement.
When they don't, they're just getting in the way.
Sedentary positions often cause nerve compression between muscles and bones, resulting in inflammation, pain, and numbness. Underused muscles atrophy, which means reduced strength and a decreased metabolism, while muscles shortened by bent legs and poor posture tighten over time, making movement harder, of course, but also reducing how helpful they can be to every other system that depends on them.
5. Your Brain
You probably already know that physical activity makes you smarter. You may not have known that it does so by triggering the production of brain-derived neurotrophic factor (BDNF) that actually grows neurons.
BDNF also fights the effects of cortisol,the stress hormone that effectively shrinks your brain.
Bad news: sitting and remaining sedentary help your body produce and hold onto harmful hormones like cortisol while limiting helpful hormones and neurotransmitters like BDNF. And, as you may have gathered, decreased blood flow and less efficient metabolism caused by sitting rob your brain of vital oxygen and nutrients needed to keep you sharp and in a good mood.
Stand Up for Your Health
We like quick fixes. While our work days get longer, high-intensity workouts like CrossFit and kettlebells are gaining in popularity, but doctors are warning that short periods of physical activity can't make up for days spent sitting. The National Institutes of Health is recommending we find new ways to discuss and prescribe more effective daily routines.
Does that mean you need to find a new job? Or stand for 12 hours a day? Probably not. But there is a quick fix you can make starting today. Choosing to sit for rest, rather than work, can dramatically improve how well all your vital systems function.
Job Orton may have said it best over two hundred years ago in 1777, when he poetically claimed, “A sedentary life may be injurious. It must, therefore, be your resolute care to keep your body as upright as possible when you read and write; never stoop your head nor bend your breast. To prevent this, you should get a standing desk.” Good ideas don't always need scientific validation, it seems.