Is sitting really harmful?


“Sitting all day is killing us!” I can’t tell you the number of times I’ve read or heard that statement in news articles this year. We all understand that inactivity in general is bad for us, but it’s almost reached fad levels lately to say that “sitting is the new smoking” (that’s another line I’ve seen echoed across many sources). While I’m a very active person, my job definitely is not, so when I see news stories saying “Sitting will kill you, even if you exercise” it certainly piques my interest. Before you run out and buy that standing desk, let’s look at some of the issues around sitting to see if it really is the killer the media is making it out to be.

What happens when we sit?

Within minutes of sitting motionless, your metabolism drops to about 1 calorie per minute and the enzymes that assist in breaking down fat for fuel drop by about 90 percent. This is part of the scare story you see mentioned in all kinds of articles and news stories, but it’s not really a concern since these two factors return to normal just as fast once you stand up again. The real dangers come in as you sit motionless (I’ll explain why that matters later) for hours at a time.

As you continue to sit, the blood vessels in your legs start to constrict and become less responsive (less likely to dilate in order to deal with increased blood flow). Activity keeps your blood vessels responsive, but sitting too much day after day eventually causes the smooth muscle of your blood vessels to permanently loose responsiveness. This leads to chronic high-blood pressure and eventually causes cardiovascular disease.

Prolonged sitting also causes your body to become less efficient at managing blood sugar levels. As I’ve mentioned in a previous article, the contraction of muscle fibers triggers a pathway outside of insulin to pull sugar from the bloodstream and into muscle cells. This is why activity increases insulin-sensitivity. If your body is always flooded with sugar and the corresponding insulin meant to deal with it, eventually your cells become less responsive to that hormone. Dealing with sugar without using insulin keeps your cells responsive to insulin, so less is needed to get the job done. Inactivity, however, means that your body’s only option is to shuttle blood sugar into cells using insulin. In time, this leads to type 2 diabetes as your body releases more and more insulin to deal with all the sugar in your system in the hopes of forcing your insulin-resistant cells to listen. It’s also why type 2 diabetes is reversible until it isn’t. Your glands have a lifetime limit of how many hormones they can produce. Pushing your pancreas to produce huge amounts of insulin for too long will eventually push the organ past a tipping point you can’t return from.

Ultimately, these are the two big concerns about sitting:

1. Decreased vascular responsiveness which leads to chronic high blood pressure and cardiovascular disease.

2. Decreased blood glucose control which leads to type 2 diabetes.

Not everyone agrees it’s a killer

Now that I’ve scared you about why sitting will kill you (the same way every other story does), let me first explain that not everyone agrees sitting itself is the cause of increased mortality risk. While the review of 47 studies that started this craze claims that exercise cannot counteract the effects of sitting, one review of 43 studies found no correlation between occupational sitting and mortality rates, and another review over the course of 16 years found that activity is what decreased mortality rates rather than simply standing more. This makes far more sense to me since movement is what actually helps mitigate the two big risks of sitting: decreased vascular responsiveness and decreased blood sugar control.


Sitting doesn’t undo activity

I agree that prolonged inactivity is bad for us, but I hate the message that sitting makes activity useless. This has caused two rather harmful outcomes that I have spent the year trying to undo in friends, family, clients, and lolo customers:

1. “If I’m sitting all day anyway, I guess I shouldn’t bother exercising.” As I mentioned above, movement is what matters, not just standing more. The message of movement doesn’t matter creates a sense of doom and futility that convinces people to abandon the very activities that will prolong their lives. I understand the point everyone was trying to say which was “move more,” but a lot of the phrasing I’ve seen over the past year can and has delivered the opposite message. Don’t give up on your activities because you have a desk job. Stick with your exercise routine and simply break up your sitting every hour (at least) with a quick bit of movement. Getting up and walking around for a minute every hour will protect you from the harmful effects of occupational sitting.


2. “I shouldn’t do cycling because the sitting makes it useless.” Cycling is a great exercise and one I recommend all the time, especially for beginners. A lot of beginners come out of the gate too hard and hurt themselves before their bones, joints, and muscles are ready for the increased stress of exercise. Typically, this is from people hopping off the couch and going for a lengthy run. This usually leads to shin splints and knee and foot injuries. I typically tell deconditioned beginners to start with walking or cycling as their first cardio workouts. Cycling in particular is excellent for people who are already suffering from knee pain. It’s a great way to rehab the joint and strengthen the supporting muscles, plus you’ll burn a ton of calories, even though you’re sitting down.

Don’t sit still

Cycling works because it gets your muscles contracting, even though you’re seated. Like I said above, it’s sitting motionless that’s harmful, not just sitting. In fact, a recent study found that women who fidgeted while seated did not suffer increased mortality risks from too much sitting. It once again gets back to movement. Even though your muscles aren’t carrying your weight, getting them moving improves your blood glucose control and vascular responsiveness.

Don’t get too focused on one thing

Like with most health-related stories, these anti-sitting articles get people too focused on one facet of their routine rather than the whole picture. Simply switching from a sitting desk to a standing one isn’t going to save you if you never exercise and you eat a comically unhealthy diet. Sitting all day at work isn’t going to give you diabetes if you’re already keeping your sugar intake reasonable. Stress is also harmful to your health and stressing out that your desk job is killing you isn’t exactly going to help. Sitting can be harmful, but it’s negative effects are easily overcome with a good diet and a little bit of movement every hour. You don’t need to buy an expensive standing desk to prolong your life. Just get in your workouts wherever you can (because they do matter), and simply try to add more movement into your day.

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