First let’s understand that muscles will feel ‘tight’ due to the joint shape and position.
For example, if I lack internal rotation (ability to put force into the ground), I may orient/dump the pelvis forward as I arch my lower back.
Now the hamstring muscles – as a quick example, will be ‘lengthened’ with this orientation of the pelvis. Therefore, the hamstrings will now contract hard to stop any damage from occurring (pulling muscle off the bone).
There are your ‘tight’ hamstrings!
Stretching them won’t achieve anything, you need to alter the joint shape/position that they attach to.
Now the reason why your chest muscles became ‘tight’ or the chest wall compressed is down to the back of the body compressing first in order to push the body towards the toes.
Why would the back of the body compress to push us towards our toes?
Answer: To deal with gravity!
If I can’t produce force into the ground, by shoving my body forward, I will create more pressure in the balls of my feet/toes which will help put more force into the ground (keeping me upright against gravity).
So as I squeeze/retract my shoulder blades and arch my lower back I shove myself forward, then the chest wall will eventually have to compress to push me back – as the nervous system gets worried that I am falling TOO far forward.
So stretching or ‘opening’ the chest whilst arching the lower back and squeezing the shoulder blades together is simply reinforcing why the chest wall closed and compressed in the first place.
This rock back exercise would be far more effective as I am achieving chest expansion whilst keeping my lower back open without completely compressing in-between the shoulder blades.
Here I would cue an inhale as I push my ribcage back towards the shoulder blades, exhale and hold the new position. However, as you push the ribcage up towards the ceiling or back towards the shoulder blades you must not crunch the front of the body. Keep long through the ‘zipper of the fleece’.
