Why is my posture related to my poor shoulder movement?

It's well known and well documented that poor posture, be it at a desk, a chair in general or in standing, can lead to low back pain and neck pain, in addition to muscle imbalance. But why does poor posture lead to poor shoulder movement?

Answer: Biomechanics!

You may feel that the arm and shoulder movement comes from one joint, but in fact, at least three different areas of the body come into play in order for you to lift your hand fully in the air!

Let's go through them all one-by-one

1. Glenohumeral joint movement

Or to you and me: The ball and socket joint itself!

The glenohumeral joint allows most of the movement. This joint allow the arm to move from your side to approximately 160 degrees into the air. The image to the left is a good approximation of this.

2. Posterior rotation of the clavicle

Or to you and me: backward rotation of the collar bone

The clavicle is not fixed! It has movement between it's fixing at the sternum (breastbone) and acromion (Shoulder) By rotating posteriorly (backwards) the arm moves another 10 degrees closer to your ear!

3. Thoracic extension

Or to you and me: The middle of your back leaning backwards

Not to the extreme of this image, but that demonstrates the direction of travel in the thoracic spine (middle of your back). The vertebrae move against each other to allow the final 10 degrees of movement which allows your arm to be beside your ear.

What does this have to do with posture?

When we think of poor posture, we think of this. A Slumped posture. Shoulders forward

Body leaning forward

Whilst the body is in this position, it is impossible to get your arm by your head! Try it for yourself. Slump in the chair and try and lift your arm fully in the air without leaning back! By sitting up, in a good posture, we maintain our shoulder movement. Which goes part way to explaining why people with stiffened and kyphotic (arched) spines have difficulty with shoulder movement.

Some congenital dysfunctions predispose some people to unavoidable reduction in shoulder range of motion. This cannot be prevented or halted. The one thing you can prevent is poor posture. Change what you can change to maintain maximal range of motion to all of your joints. If you struggle with poor posture or would like further advice on this, then please contact us on the details at the top of the page.