Serratus Anterior Front

The “Boxer’s” Muscle

Also known as the Serratus Anterior, The Boxers Muscle is located deep under the scapula (shoulder blade) and wraps around the rib-cage under the Pectoralis Major (chest muscle). You can feel it if you place your hand under your armpit and push the shoulder down.

Serratus Anterior Front
Serratus Anterior

Why do we need a Boxers Muscle?

The Boxer’s Muscle pulls the shoulder blade forwards around the rib-cage so, for example when boxing and you go to punch someone that muscle brings the arm forwards and gives you a few extra inches or power to contact an object.

The classic Bruce Lee “One inch punch” is the perfect example of the power the Boxers Muscle can generate.

The Boxers Muscle has other roles in movement and posture.  For posture, it helps to keep the shoulder blade in place along with other the other muscles and can determine things like neck position.  Other roles including lifting the shoulder blade up and out as you raise your arm up and providing stability of your trunk and torso when you need to push off from something.

Short answer – punch harder; push harder, raise your arm and assist your posture  

So what goes wrong?

This muscle can contribute to injury, pain or reduced performance in many ways:

1. Let’s start with posture. 

Caveat – “Good” posture varies between individuals and it is always about having everything in the right position for you to function to achieve the goal you want to do as efficiently and effectively as possible

So, if you have a sore neck from being in front of the computer all day the Boxers Muscle can be a factor.  If the outside of your shoulder blades look like they are dragging downwards then it is likely the muscles having to hold them up are not working.  Now the upper traps often cop the blame but they undergo a “hanging on for dear life” philosophy and get tired.

What has happened?

In the normal course of day to day life in front of our computers and using our arms in front of us, the group of muscles of the shoulder blade and arm get over-worked over a long period of time and the body tries to find new ways to do the same thing.

Enter the pec-minor

I once spoke to a well-credentialed shoulder surgeon who said if he had his way, he would cut everyone’s pec-minor off.  Well I don’t think we should go that far but the pec-minor sitting under your chest muscles assist the Boxers muscle in bringing the shoulder blade forward BUT it also rotates it downwards.  Eventually, pec-minor pulls rank and Boxers muscle becomes dysfunctional.  The shoulder blade rotates forward, upper traps get stretched and then our other nemesis the Levator Scapulae kicks in to help and holds the shoulder blade up on the inside but rotated downward and forward on the outside. 

Levator Scapulae and neck pain

The LevScap is usually our tension headache muscle.  It is now forced to work overtime at the shoulder blade with the Pec-Minor and the result is the neck posture and pressure has increased demand.  The consequence your posture adapts and places an increased demand on the back of the neck joints and muscles.  Over time the ability to sustain these postures is compromised and headaches or neck tension or even the odd “Acute Wry Neck” may develop.

2. Pushing and pressing related pain in the shoulder

Those who undergo exercise, especially for the first time or after a while, normally incorporate a lot of upper body exercises which involve pushing, pulling and pressing etc. 

Why?

Let’s be honest we like to have nice shoulders, arms and chests and we can see nice quick changes in this area.

If we are coming from a sedentary background or we haven’t trained in a while (or we do too much) then the Boxers Muscle is often asked to increase or alter how it works quite quickly.

As per posture, everyone’s styles are different depending on their goal but when we push or press, we tend to feel stronger when we roll the shoulder blades in and forward, wing the elbows out and roll the forearms in.  We then push and press until we cannot no more. 

Under the same principles of the postural adaptations the other shoulder blade muscles do more work and this often has 2 effects.

  1. Eventually reduces the space between the shoulder and the shoulder blade for all the arm muscles and tendons to function.
  2. Changes the effectiveness and efficiency of those muscles (working harder / getting fatigued sooner).

The Boxers Muscle and other muscles can be trained to assist in coming up with a new strategy to avoid the compression of the shoulder tendons or reducing the muscle efficiency.  So after you have had your shoulder blade function assessed along with your shoulder muscles you can start retraining your Boxers Muscle – if dysfunctional – to work differently to support your shoulder to press, pull and push more.

3. Throwing and Punching related shoulder pain

When punching and throwing the Boxer’s Muscle not so much causes the problem but in many cases is the victim of it.  To generate power in a throw and a punch most of the work is done in the trunk and hips.  When throwing over 40% of the power comes from the trunk alone. To do this it requires a very stable base to generate ground reaction forces to develop the power required.

So why is the Boxers Muscle a problem here??

Its role in these cases is to bring the shoulder blade forward quickly and transmit the force from the trunk into the arm and then output at the hand. Due to a number of things such as reduced ground stability; coaching positions and cues and overuse the trunk can be rotated forward at the time the power is transferring to the arm.  This means the shoulder blade is in an in an inefficient position to transmit that force (and slow down afterwards) and more demand is put on the shoulder itself to generate force lost.

Reduced Inefficient Lower Limb Stability

Ultimately repetitive movements such as jabs, hooks, uppercuts etc and throwing has implications on the shoulder stabilisers and does not allow them to do their job effectively and efficiently. Then there is increased demand on the smaller muscles of the rotator cuff which can put strain on them and result in a tendinopathy, rotator cuff tear, bursitis or impingement –> Sore shoulder

There are other reasons the Boxers Muscle does not work properly including Long Thoracic Nerve Palsy, where the nerve to the muscle is compromised and the muscle does not work. These are best assessed clinically and understand if there is a pinched nerve or other underlying condition causing the problem.

How do I know if my Boxers Muscle is working?

Over time a dysfunctional Serratus Anterior can result in scapula winging. A winging scapula is when your shoulder blades stick out rather than flat on your back as seen in this photo.

Scapula Winging

Assessment

Wall push up test

  • To help identify Boxers Muscle dysfunction.

Place both hands on the wall shoulder-width apart and hands in line with the shoulders and complete 5 push-ups (Nose to wall and keep hips straight). Get someone to watch or video it yourself. During this movement, if this test is positive you will see the shoulder blade protruding from the back, and if someone is there, they may even be able to fit their fingers in behind the shoulder blade. If the shoulder blade appears normal you can repeat the same movement with a single arm and watch for any abnormal movements or differences from side to side.

  • Testing Strength

Handheld dynamometry can be used to assess shoulder blade protraction strength.  Even though protraction is done by the Boxers Muscle and the pec-minor together, we can combine this test and a few other little signs that we can see and see if the Boxers Muscle may need some work.  We aim for about 30% of body weight in kg, same as the other side and same as retraction.

Other things to look out for

  • Restricted upper body rotation
    • Sit on a bed with feet on the floor and arms across chest
    • Rotate upper body each way without backside muscles coming off the bed and feel which one is tighter or more restricted (we usually measure with a laser goniometer and aim for within 10° each side and around 65° each way)
  • Poor balance on the opposite leg or shoulder rotating forward as you shift on to one leg
  • Tightness in pec-minor when stretching (very crude tests but they all add up). Lie on your back with your arms by your side relaxed and see if the outside tip of one shoulder is higher than the other.

How do we make it work again?

Once you’ve identified the Boxers Muscle is a problem then it may be a case of

  • Re-training it to work
  • Strengthening it
  • Improving the other contributors such as hip/trunk strength and movement control
  • Managing the shoulder and/or neck issues

Putting it all together

Your program should integrate all those things above to work for you and the goal you have. 

It is important that when you rehab these that you do so to make sure you perform to achieve what you want.  A good program will build your capacity, integrate your skill and teach you how to stay that way.

#beabetteryou 

Exercises

1. Serratus Push up on the wall progress to knees and again on toes.

Serratus Push Up

2. Shoulder protraction with dumbbell.

Serratus Shoulder Protraction

3. Wall slides with roller.

Serratus Wall Slides

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