You may already know "sitting is bad" and that "you need to sit up straight", but why? Is there anything beyond the respectful nature of proper etiquette that would compel you to sit differently?
Today we will cover major 3 problems with sitting:
1) Poor "slouched" posture that relies on bony end ranges to maintain support
2) Overly upright posture that relies on tense musculature for support
3) How sitting is training you to move poorly and the simple formula to fix it.
The First and most common form of poor posture is related to the classic slouching position. Mechanically speaking this means that a rounded spine is not only flexed forward but also has an overly shift center of gravity that also falls forward. This anterior biased skeletal position compresses the muscles in the front of the body and extends the posterior musculature to the point that renders muscles on both sides ineffective subsequently placing the bulk of the strain on the joint. (Nothing groundbreaking here... yet)
Now, joints that were meant to transfer the forces placed on them begin to absorb an undue amount of that force that they were not built to endure.
The second error that is commonly made can also strain joints but is more commonly felt as an overly tense group of muscles that "have a hard time relaxing". The image above on the left is a great example of a spine that is the opposite of the typical slouched posture. The spine is hyper extended.
The clinical element that is often missed in this situation is the same as the slouched posture... it is a spine that has shifted its center of gravity FORWARD.
You can see that the major issue here is the spine and that perhaps corrections to the spine itself can cause more problems.
Why does correcting spinal movement often cause more problems than solutions?
While I do not think spinal movement itself should be ignored; I do think that it may not be the best way to help someone. (Now we get to the good stuff)
The main issue here is that mechanically speaking the spine does not actually have that much movement in-itself. The muscles surrounding the spine are small stabilizers that are more reactive and quick than strong, and sitting literally trains those small stabilizers to become LIKE prime movers.
The classic image above shows how the tilting of the pelvis moves the spine. This is the proper sequence.
The primary movers of the hip move the spine primarily, until you sit, trap the hip, and train your spinal accessory muscles to become the primary movers.
The next and often unnoticed feature of the image above is also the way out of this predicament. Look again and you will notice that in each example the femur is also consistently stable. In other words the formula here for the natural alternating nature of the body is:
THIS IS THE KEY FORMULA!!
Stable (fixed) femur, Mobile (force absorbing/creating) pelvis and then back to the stable (fixed) spine.
Chairs seem to naturally with literally no effort at all invert this simple formula, but the correction is simple.
The best correction is to put some life back into the hips. Make the hips the prime mover again. Deadlifts, squats and maybe even a simple hip flexor stretch can begin to help. The main issue with the cure is that it often does not match the problem in one specific way...
Sitting is not an intense activity, but the shear amount of time many of us spend sitting may often require a correction that has a longer duration than we may realize.
There are a TON of ways to reassert the natural formula I stated above, but if it is also not coupled with enough force and repetition it can easily slide back into it's old habits.