Why the Cause of Tight Chest Muscles is a Stiff Upper Back

Why the Cause of Tight Chest Muscles is a Stiff Upper Back

On the surface, treatment for tight chest muscles is well-defined. All you need is a consistent stretching regime to loosen those tight chest muscles up over time. It a no-brainer, right?

But, what if I was to suggest that there's more to tight chest muscles than many think?

As an experienced Physiotherapist (Physical Therapist), I'm not satisfied with the idea that chest muscles just happen to get tight. And I'd also like to challenge the long-held belief that tight chest muscles are the first step in creating a rounded shoulder posture.

Instead, my clinical experience has taught me there may be another, more counterintuitive cause of chest muscle tightness and its related dysfunction.

To be honest, it's hard to create too much suspense considering the answer is literally in the title, but I think the way we currently look at the cause of chest muscle tightness lacks a little perspective.

And from what I've come to understand, the underlying cause of chest muscle tightness is a stiff upper back.

Now, this may sound strange considering your chest muscles are at the front and your upper back is, well... at the back, but mechanically they share a strong, tangible link. One we often miss but is simple to rectify if we just take a moment to look for it.

And this is important as tight chest muscles may contribute to the cause of shoulder pain and shoulder injury.

So join with me as we discuss why chest muscle tightness is actually more than chest muscle tightness, why a stiff upper back might be the underlying cause, and what you can do to never have to stretch a tight chest muscle again.


Chest Muscle Anatomy

For those unaware, chest muscle tightness is a decrease in the available range of motion of two specific chest muscles - the Pectoralis Major and Pectoralis Minor.


Pectoralis Major

The Pectoralis Major is the most notable of the two chest wall muscles and responsible for the classic chest shape. Commonly referred to as the "Pec", it's a strong, powerful muscle that attaches from the top of the arm and anchors onto the front of the rib cage and sternum.

As the most superficial of the two, the Pec Major is often the muscle that feels physically tight. Therefore, it's the target of most chest stretching.

pec major and pec minor


Pectoralis Minor

As the name implies, the Pectoralis Minor is the smaller, more covert sibling of the two chest muscles. It attaches from a small notch at the top of the shoulder blade and, like the Pec Major, anchors onto the front of the rib cage.

Despite its relative obscurity, the Pec Minor is often quite tight on many people and a subtle contributor to a lot of shoulder pain and shoulder injuries.


Hidden Cause of Chest Muscle Tightness

Moving along, let's discuss why I think there's more to chest muscle tightness than tight chest muscles.

From the image above, you may notice that both chest muscles anchor to the front of the rib cage. This is important as it defines why they become tight in the first place.

The body has this process where it prioritizes the function of a poorly loaded and dysfunctional area by recruiting connected structures to help out. The chest muscles' attachment to the front of the ribcage means they are asked to help out when the ribcage itself becomes dysfunctional.

If the rib and spinal joints at the back become overloaded, most commonly due to poor posture and positioning, function can be drawn from the front to support.

In short, the body uses muscles at the front of the chest to help support what's going wrong at the back.

The thing that makes this difficult, however, is that the body seems to alert us to feelings of tightness more than feelings of stiffness. So we notice when our chest muscles become tight, but not the preceding stiffness at the back. We all know how a tight muscle feels via an obvious 'pulling', but stiffness often just stops and diverts movement (and our attention).

And because of this, it's easy to get stuck in a loop of consistently stretching your tight chest muscles without ever really making them 'looser' over time.

Because you can't.

Stretching a tight muscle only attempts to loosen that tight muscle. But if your brain and nervous system has asked that muscle to be tight for a reason, it will eventually re-tighten again unless that underlying, hidden reason is addressed.



The Postural Myth

There's a popular line of thinking that tight chest muscles cause rounded shoulders. Similarly, we think stretching our chest is a common way to help improve shoulder and upper back posture.

Now, this is still true to a degree because tightness at the front does essentially hold us in a poorer, more rounded shape. It does restrict the ability to pull our shoulders back. But we've missed the crucial step before.

Clinically, poorer posture creates the need for tight muscles in the first place. This then makes it harder to get back into a good posture again, and off on a downward spiral we go.

So we're doomed to fail if we just stretch our chest and hope it improves our posture. We need to accept the responsibility of actually trying to get into better positions as well.

Similarly, upper back stiffness creates a block that makes it very hard to bring our shoulders back to a good position. So without addressing this stiffness, it's hard to open up space for those shoulders and shoulder blades to reposition themselves.

In short, tight chest muscles do contribute to poor shoulder posture, but they're not the root cause. They're a side-effect.

Related: 13 Common health and fitness myths you didn't realize were false.


How to Best Stretch Tight Chest Muscles (and Keep Them Loose)

The key to solving your chest muscle tightness relies on navigating through three key elements.

We need a series of exercises that:

  • Stretch your tight chest muscles
  • Mobilize the hidden underlying upper back stiffness
  • Help you prioritize better upper body postures and shapes

And if you want them to stay loose, you need to keep an eye on them over time.


Mobilize Your Upper Back

The first step to loosening up your chest muscles is to address that upper back stiffness.

upper back mobilisation with lacrosse ball

To begin, find a ball of your choice. A lacrosse ball works amazingly well for this (you can get one here - affiliate link). Next, lie down and gently let the ball press into the tissue either side of your spine. Move it around until you find tissue that feels stiff and possibly tight.

Don't let any tenderness or soreness seduce you, prioritize areas that feel stiff and tight. Once you've found some relevant areas allow the ball to sit there for a few minutes until it begins to give. Then, move on to the next area.

To amplify the results, lift one arm up above your head and towards the ground. Oscillate in and out of your end range to really sheer those stiff joints free. After a few seconds, you should start to feel/see your arm go further - indicating those joints are loosening up.

Here's a video I put together on how to use a ball to improve your upper back mobility and, in turn, your shoulder flexibility.

Stretch Your Chest Muscles

Next, it's time to undo the consequence of those stiff upper back joints.

We don't need to re-invent the wheel here, so any pec stretch that gives you access to your chest muscle tightness is worthwhile. An easy option to consider is the pec stretch with a door frame.

Place your forearm and elbow up against a door frame and gently twist your trunk away. Move your forearm higher or lower to bias different areas of the chest. Similarly, dip your shoulder down to target the very top corner of the chest. At the end of the day, just go hunting for the best stretch.

Once you've found a good stretch, tense the muscles of the chest and shoulder for a few seconds to get your brain involved. This is called Proprioceptive Neuromuscular Facilitation (PNF) or the 'contract-relax' model. Upon relaxing, you should feel you have immediately fewer feelings of tightness.

Repeat this process for a few minutes or until you stop making gains.


Practice Better Posture

This is probably the least sexy but most important factor in ridding yourself of tight chest muscles. It all starts and ends with the quality of your default shoulder posture.

To optimize your position, stand up tall and gently pull your shoulders back. It's not fancy but it's crucial to start the process of normalizing your tissue and its function. If you then need to sit down, literally nothing about your head, neck and shoulders should change. It's the same shape.

The challenge with this is that many can reclaim a decent shape but find it hard to maintain as soon as your attention is needed elsewhere.

We don't often sit to just sit anymore. We sit to read, use our phones, veg out in. front of the TV, commute, etc. So it's almost impossible to focus on your posture all the time. So please don't feel bad if you can't.

Aside from decreasing the time we spend sitting, which isn't always practical, the next best option is to arrange your environment to support better shapes.

Place a pillow or rolled-up towel in the small of your back. Lie down instead of sitting on the couch. Adjust your car or your work station to suit your best posture so that it pulls you back there constantly.

Similarly, you have to check in with yourself throughout the day. Starting off in a good shape in no way means you'll stay in a good one for too long. Remember, chest muscle tightness rarely exists when supported by good postural habits.

And by recalibrating your upper body positions you can keep your upper back and those tight chest muscles lose over time.


Frequently Asked Questions

How do you release a tight chest muscle?

Traditionally, loosening up chest muscle tightness requires a pec stretch. However, in order to keep it loose, you need to go after its root cause - upper back stiffness, and poor posture.

Why is my chest muscle tight?

Chest muscle tightness is ultimately the consequence of poor resting shoulder postures and upper back stiffness. Think of your chest muscles having to help support dysfunction at the back - from the front. Pec stretching alone won't stop your tight chest muscles from wanting to be tight unless you also address its underlying cause.

Can tight chest muscles cause back pain?

In severe cases, tight chest muscles can increase your risk of shoulder, neck and upper back pain. They do so by altering the normal loading and function of the upper body. It's important to note, however, that chest muscles do not get tight on their own. As mentioned, poor posture and upper back stiffness set them up to be tight in the first place.

Can tight chest muscles cause shortness of breath?

Mechanically, tight chest muscles can influence the efficiency of our breathing. Ribcage function plays an integral role in allowing us to breathe normally, and anything that restricts its function has the potential to decrease breathing quality. Stiff ribs, poor positioning, and tight chest and upper back muscles are three of the most common handbrakes to normal breathing mechanics.



Chest muscle tightness is important to address. If left alone, it can affect your posture and contribute to a range of shoulder pain and dysfunction.

With this in mind, it's good to have a decent pec stretch in your arsenal to pull out when needed. However, without understanding the role upper back stiffness plays in creating these tight chest muscles, we may never conquer it completely. And, like many, we can easily get stuck in an infinite loop of stretching and re-tightening, without making a meaningful change over time.

So if you'd like to truly conquer your chest muscle tightness, aim to mobilize your upper back and prioritize better shoulder posture. Only then can you finally begin to have a conversation about what it feels like to be free of those tight chest muscles.

Good luck!

Do you suffer from chest muscle tightness? Let me know your go-to chest muscle stretch below.

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