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How Harmful is Too Much Sitting?

We’ve all heard the party line: Sitting is the new smoking. Maybe not exactly, but a sedentary lifestyle for a non-smoker is turning out to be as harmful as a pack a day over the course of a lifetime.

 

People who sit for more than about 9 or 10 hours each day tend to face obesity, higher cortisol levels and inflammatory issues, diabetes, and earlier risk of death from multiple causes. This is true even if these people exercise a few times a week.

 

A new study looks directly at the HEART of the matter when it comes to sitting. Excessive sitting also has been associated with heart failure, a condition in which the heart becomes progressively weaker and unable to pump enough blood to keep the rest of the body oxygenated and well. What we haven’t known is the why…but we are starting to understand this now.


When someone has a heart attack, the heart muscle releases proteins called troponins into the bloodstream. For hours after a heart attack, we can measure these elevated troponin levels to confirm that someone did indeed have injury to their heart muscle, AKA a
heart attack.


Some people may have slightly elevated troponin levels over time, though no one incident such as a heart attack occurred. What this tells cardiologists is that damage is being done to heart muscle
often by poor blood vessel flow to this muscle. Over time, this may lead to heart failure.

 

Researchers in Texas gathered information from over 1,700 participants who all wore activity trackers and gave blood samples as part of the Dallas Heart Study. These were men and women from diverse cultural and racial backgrounds. After looking at how much or how little participants moved, researchers measured their blood levels of troponins, aka heart damage proteins.

 

Shocker alert:

Those who moved the most tended to have lowest amounts of troponin in their blood. Conversely, those who sat for 10 hours or more a day tended to have above-average troponin levels.

 

The above-average levels in those who sat all day were nowhere near levels seen in an acute heart attack, yet the researchers found them high enough to be called  “subclinical cardiac injury.”  

 

My take home here: Sitting was more strongly associated with unhealthy troponin levels than exercise was with healthy troponin levels.

 

To put it another way: Heart muscle breakdown is strongly linked to sitting all day, most days. So much so that even if you exercise the rest of the day, your levels won’t “level out.” Of course, the more exercise you do, the fewer hours you sit. Notice this has nothing to do with heart rate or calories burned. It has to do with movement or no movement over long periods of time. Period.

 

Not the best news for those who try to combat hours at a desk all day with 3 workouts a week. Good news for those who have already started mini walks each day.

 

This same research team is planning on taking things a step further (no pun intended!) to look at how much exercise can offset the sitting when it comes to heart damage.

 

This will be important in how we modify our days: if we must be at an office deskhow often do we get up and take a walk around the block? How many flights of stairs should we aim for? How much proof will companies need before they invest in stand-up desks for those employees whose good health they need?

 

For now, the message remains the same. Get up and move! It makes you happier, it makes you live longerand it’s great for your heart!

 

Written by

0phthalmologist & Health Professional

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