48,360 hours. That's how many hours you'll sit at a desk over a 30 year office career. That's the equivalent of five years of your life.
One of the most common pieces of advice you'll have when it comes to sitting is to take regular breaks from the desk and from the screen. There's a whole heap of reasons for this, but one of the most common and overarching is to avoid the phenomenon of muscular creep.
Muscles have what's called a Viscoelastic property. This means muscles behave half like water
and half like a rubber band.
Because of this rubber-water characteristic, when we hold a posture for any length of time, our muscle tissue gradually lengthens and creeps. This process starts the moment we stop moving, so it's not exclusive to sitting, but there are some reasons why it’s particularly dangerous and particularly harmful when we do sit for extended periods of time.
When we sit, the body is in a flexed position, this lengthens out and stretches the muscles trying to support and extend the spine. As creep sets in, those back muscles that were already in a position of disadvantage become more and more disadvantaged and inhibited as we slouch further and further, leaving us hanging off our ligaments and the passive structures of the spine.
When you combine the compression from sitting plus the flexion of the muscular creep, that force going through the disc gets sent rearward towards the back. That's stretches at the rear wall of the disc and puts it under more stress than it needs to be.
When we sit our rib cage drops forward compressing on the lungs, squashing and inhibiting the diaphragm. This subtle restriction on air flow blocks oxygen delivery to the brain which is going to slow down our thinking, concentration and cognitive processes.
Forward Head Posture
We have touched on neck position previously. As the head creeps forward to the screen, book or papers it becomes relatively heavier places extra strain on the muscles at the back of the neck as they work to support it. These muscles (namely levator scap) become exhausted trying to hold it up.
Now it's time for some fixes
First, just become more posture aware. Being mindful of how you are holding yourself when you sit can be enough to break the hold of creep.
You only have to consciously remind yourself every five to ten minutes, adjust, wiggle around in your seat, straighten back up, and then get back to work.
Secondly, a little bit of fidgeting actually does wonders for reducing the effect of creep. Not the annoying fidgeting that I tend to do where you make heaps of noise and distracting everyone in the office or classroom, but little adjustments of your posture, little tweaks and shifts, as long as you're not annoying your co-workers or your classmates every now and again is enough to re-engage the nervous system, interrupt creep, and shift the load to different muscles or joints, distributing the forces more evenly through the postural muscles.
And lastly, set a timer every 30-45 minutes to take regular breaks from the desk. Stand up, do a couple of squats, grab a glass of water or do one of these other anti-desk workouts to undo some desk tightness.