The thoracic spine describes the 12 vertebrae of the upper back and abdomen that sit between the cervical spine of the neck and the lumbar spine of the lower back.
Each thoracic vertebrae has articulations between its neighbouring vertebrae (above and below), and to the attaching ribs.
Now, if we were to look at each segment of the spine, they each play an important individual role in movement.
The lumbar spine is a stable segment that provides a strong supportive base for the muscles of the trunk.
The lumbar spine does not have much mobility, as it is designed to bear and withstand load rather than create movement.
By acting as a stable support structure, it can aid movement and force production at the hips.
The cervical spine is similar.
While it allows much more movement than the lumbar spine (we need to be able to look around) it is still considered a stable joint, as it provides essential stability to the fragile neural structures of the neck.
But the thoracic spine is somewhat different.
It is actually considered a mobile joint, and is the spinal section that has the largest range of movement.
This is important as it allows us to rotate, flex, and extend.
All of which are extremely important during running, sprinting, changing direction, jumping, and during throwing movements.
In the wonderful age of technology that we currently live in, we spend a lot of time sitting (and not a lot of time moving).
This results in REALLY stiff and immobile thoracic spinal segments, which as you can probably guess, is not good (this thoracic stiffness is often typified of excessive kyphosis and forward head posture).
If a segment of the body is lacking essential mobility, we tend to find it at another segment.
This is a compensation pattern that allows us to complete the movements required, despite lacking the mobility to do so.
While these compensation patterns are helpful in the short term (they allow us to move), they can lead to chronic dysfunction further down the track.
In the case of the thoracic spine, if it is lacking mobility we are going to find mobility at the lumber spine.
Now, as we mentioned earlier, the lumber spine is not actually made to move much at all.
Rather it is meant to act as a stable base from which both the thoracic spine can rotate, and the hips can move freely to produce force.
If it is forced to become more mobile, this is going to lead directly to dysfunction, and may also have negative effects further down the kinetic chain.
Firstly, we lose stability at the lumbar spine.
This is an issue in itself, because if the lumbar spinal segments move more than they are supposed to, we can irritate both neural structures of the lumbar spine, and the passive support structures around the spinal segments.
This can lead to low back pain and low back irritation.
Secondly, by losing stability at the trunk, the lower limbs no longer have a stable base to produce force.
To try and get the point across with analogy (who doesn’t like a good analogy?), picture a slingshot.
If you hold the base of the slingshot firmly, you can load and shoot much further. If the base of the slingshot is held lightly, it is going to be loose and weak, and your ability to shoot with it is going to be limited.
Now, the base of the slingshot represents the trunk, while the top portion represents the hips (or upper limbs… works for both really).
When the trunk is stable, we can produce great amounts of force at the hip.
If the trunk is too mobile, that force production is limited.
Additionally, it is quite common to see the muscles surrounding the hips try to produce the stability lost at the spine.
This results in shorty and stiff muscles surrounding the hip joint, which can lead to limited movement of the hips, potentially leading to a soft tissue injury, or an injury of the surrounding joints.
And, just to make things worse, having poor thoracic mobility can also increase our risk of developing shoulder injuries.
Many movements above the chin require a significant amount of thoracic extension to be completed safely and effectively.
If we think about overhead movements such as overhead presses, push presses, overhead squats, snatches, etc, etc, etc (the list goes on and on), they all have something in common.
They require the ability to get our arms over our head into full shoulder flexion.
Now, thoracic extension is a big part of this.
If we have a mobile thoracic spine that can extend easily and with good range of movement, it actually requires less shoulder flexion to get our arms over our heads.
This ensures we rely on the muscles surrounding the shoulder joint and shoulder girdle for stability.
If we have poor thoracic spinal mobility (stuck in thoracic flexion), we have to use more shoulder flexion to achieve the same overhead position.
This can place unnecessary load on the passive support structures of the shoulder joint, increasing our risk of developing injuries.
So to summarise, if we have poor thoracic spine mobility we are at an increased risk of lower back, shoulder and hip injury, AND our force production is limited.
AKA it’s not good.
Fortunately, there is something we can do about it.
We can use specific thoracic mobility exercise to increase our range of movement at the thoracic spine, making it more mobile.
Improving mobility of the thoracic spine
Thoracic spine mobilization on the foam roller