Avoid forceful arm stretches after breast cancer

If I am forced to rant- the only rant that is worth my while is the harm that certain arm stretches can do to people after breast cancer surgery and radiotherapy.

The harm is PAIN and not being able to do activities that require lifting the arm with or without weight above the shoulder.

This claim can be understood by these two scenarios:

1. Most people are told to only do arm stretches and general exercise after breast surgery and radiotherapy.

2. Using forced arm movements to regain arm movement, and not having the local sensation at the chest to feel the pain of micro-tearing, can lead to more scar tissue.

OK, now let’s back up a bit; most people receive advice about using a graduated approach to arm stretches after their surgery. This is a well-used approach around the world and usually is supported by a piece of paper with these exercises. I believe this strategy is aimed to:

1. Avoid the scenario where people do not move their arm after surgery –reducing the risk of frozen shoulder.

2. Imply a need for reduced use of the arm for a period of time to reduce physical stress at the wound site, so it heals well.

3. Gradually stretch the soft tissues around the wound site that have been damaged from the surgery.

4. Remodel the new connective tissues that have been laid down at the wound site – so they go from being disorganized to more organized to the lines of pull that are required at the chest, or breast reconstruction sites.

These reasons are so important!

But it is the first two scenarios that get my goat, because of the unnecessary limitations and injury they can impose onto individuals who are struggling to recover.

Let’s go into this a bit more.

1. Most people are told to only do arm stretches and general exercise after breast surgery and radiotherapy.

If full shoulder movement is not recovered by about 4 weeks after surgery, then more conservative treatments should be considered. Conservative treatments would involve methods to remodel the tight scar tissue- like low-level laser and specific manual therapy.

When there’s a large wound, there’ll be a large area of scar and adhesion at the skin and more where the incision occurred. The incision site will likely be well away from the tumour and node removal site because the doctors choose a location that will not be visually obvious; so the incision within the breast area is usually long for this reason.

Another example is the removal of all the breast tissue during a mastectomy and axillary lymph node dissection. Mastectomy, lumpectomy and axillary lymph node dissection will each result in a significant surface area of new scar tissue (under the skin) forms and this entire area will be less elastic.

This less elastic area at the chest is likely to directly or indirectly impact the pectoral muscle, which is the major chest muscle. The mechanism for this is the muscle is not able to glide to its full length because of shorter and more disorganized connective tissue, either directly above or in some cases connected directly to the surface of the muscle.

So why do arm stretches not work in these examples? One reason is that the tension from arm stretches will work on the tissues just outside of this scarred area – and not the entire area of the chest.

Imagine having three people holding a thick silicon disk and each person pulls from the outside edge. The stress from the pulling will be more on your fingers that are holding the outside of the disk.

But we have been working hard over the last 10 years and have found suitable manual therapy techniques that can be applied directly to the less elastic tissues: the scar tissue and adhesions while putting less strain on the tissues surrounding the 3D healed wound site or “disk”.

Manual therapy for breast cancer-specific movement impairments are available, however to date most people do not receive this service from their breast cancer clinic. Across the world, there is a low referral rate to specialist rehab providers. It’s easy to see why most people with arm movement restrictions give up hope of regaining large arm movements when they rely on the advice of arm stretches only.

Scenario 2: Using forced arm movements and not having the local sensation at the chest to feel if the tissue is micro-tearing.

The most common complaint people have after big breast surgery, like a mastectomy, is that the sensation on their chest is not what it was. The sensation can be: dull, numb or more sensitive; and the area of this sensation change can be quite large.

Now think about following the doctors’ or therapists’ advice about using an arm stretch at the end range to improve shoulder movement. How easy would it be to stretch beyond the safe zone of lengthening, when the sensation at the chest is affected? My answer is: Too easy for many of the people who come to me complaining of pain at locations outside of their scar tissue zone. Examples of this are pain at the back of the shoulder blades or pain at the side trunk.

So what is the safe zone for stretching?

The Stress-Strain model of materials can help to better understand arm movement recovery options after breast cancer

People can either push (force) their arm stretches to recover bigger arm or people don’t push (force) arm stretches. Both options are poorly understood and poorly communicated during recovery after breast cancer surgery.

The scientific mathematical study of safe and unsafe tensile (stretchability) characteristics of materials offers one way of understanding this issue. This study has resulted in a stress/strain model, where under research conditions, a scientist applies an external force or deformation (stress-calculated as a quantity of force) to material, like steel, to see how far it lengthens and deforms (strain rating) to determine at what stage the steel lengthens so much, that it fractures and becomes permanently damaged and therefore fails as a material.

My example of stress and strain comes from a common childhood challenge: how far can you pull the chewing gum before it breaks?

The answers are:

1. If it’s just come out of the packet- it takes a fair bit of finger force (stress) and the chewing gum almost tears apart before it gets too long. The strain (end length minus start length) was probably less than 10% and that’s a guess, not maths!

2. Chew it for a while, and I remember pulling it gently and getting it to about 6-8 inches before it broke and that must be a whopping 600% strain (length gain). Now that’s elastic!

Stress-strain research investigating the more elastic tissues within the body usually involves an “out of the body experience”. In research, the animal or a cadaver tendon or muscle is put into a tensioning device, and force is gradually applied until micro-tears are seen and then rupture of the tissue occurs. Science then explains that certain forces and length can be gained from our soft tissues safely, and injury or irreparable damage occurs at larger forces (stress) and longer length (strain).

This modelling describes these safe lengthening zones as phase 1 and phase 2 activities: tissues gradually unwind and then lengthen still within their elastic capacity.

Even when this elasticity is compromised by scar tissue at a healed wound site (we are thinking about the chest/ breast area specifically) it is thought that the body can encourage new remodelling: promoting some length and redirection to the new connective tissues, during these two phases and over the first two years.

Spoiler alert: Scar tissue is known to go away completely (100%) when we are in utero, but once we come out of the womb, scar tissue remains and can only be remodelled somewhat.

A generalized ligament /muscle Stress/ Strain model

Phase 3 and 4 are where the stress (force/stretch) and strain (lengthening) is sufficient to cause micro tear and then macro-rea or full rupture. Both of these phases create an injury to the soft tissues and the body’s response is to go into healing mode again: a greater production of less elastic connective tissue.

This is a good argument for me to confidently advise people who are already struggling with post-surgical tightness after breast cancer.

AVOID FORCED ARM STRETCHES- do not go into phase 3 or 4 stretching.

Can the stress-strain model explain why tendon injuries could be more likely with forced arm stretches?

I’ll take the stress-strain modelling one step further, but I need to recognize that there is no research investigating real-time post breast cancer pectoral muscle stress/ strain levels; so this is purely hypothetical, yet based on research in other tendons and muscles and limited study of post-breast cancer chest stiffness.

The variance in stress and strain of muscles and tendons is great and the variance between each one between persons might be variable. So let’s look at the general figures from some current studies. The safe elastic phase of a muscle like the diaphragm is up to 20-30% lengthening ( an out of body tensile experiment) and the lengthening of the pectoral muscle is between 10- 55% ( a cadaver arm movement experiment). Both of these percentages represent the length that the muscle can go beyond resting length. Yet the percentage stretch for a tendon (mostly lower legs tendons have been evaluated) is only just over 3% before micro-tearing occurs. This tendon lengthening rate is very low and has been found and is similar across a few different tendon studies. These figures demonstrate that the muscle is more elastic and the tendon is less elastic. One explanation is that muscle’s elasticity can dissipate and redirect stress or forces at the tendon and its attachment to the bone.

Unfortunately, this degree of muscle elasticity might not be present after breast cancer surgery and radiotherapy. From very recent research using mathematical and complicated elasticity evaluations, we now know that the pectoral muscle is stiffer in breast cancer survivors, after ALND and radiotherapy than healthy persons. This stiffness was found at rest and also when the person was engaging in a light activity requiring 10% effort.

Now, combine these three pieces of information and think about if you try to force your arm beyond comfy reach and there’s scar and adhesions and radiotherapy stiffness affecting the pectoral muscle’s ability to glide to its full length.

Firstly, the stiff muscle will not absorb some of the stress/ tension and it will pass to the pectoralis tendon. This suggests that the tension (stress) will be larger at the tendon.

Secondly, the larger the stress at the tendon, the greater the strain (lengthening) and therefore the more likely the tendon tissue will hit the micro-tear phase- when the pectoral muscle is stiff.

OR does the clever body prevent this overload at the front of the shoulder? Where the shoulder moves forward, the shoulder blade moves up and outward and the body’s posture now takes on head forward, rounded shoulder position.

Sound familiar?

Remember- this is my hypothesis, based on available evidence, to explain why people after breast cancer have tendonitis or tendon ruptures and now it seems we can add in poor posture.


1. People with large areas of less elastic skin, breast tissue and muscle can benefit from specific manual therapies applied directly to the less elastic areas.

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