Why Do I Get Blisters?
Have you ever been out for a long walk with your family then all of a sudden you become aware of a 'hot spot' about your heels?
Maybe it's a new pair of shoes, maybe it's a distance you are not prepared for or maybe it's just the wrong shoes for the wrong occasion but you know, here comes a blister.
Blisters are a very common skin injury
What Are Blisters?
Blisters are a common skin injury that affects people of all walks of life and activity levels.
These fluid-filled lesions can not only cause pain and disablement, but they can also lead to ulceration and infection in the at-risk population of people with diabetes and circulation disorders.
Most people blame rubbing (friction), heat and moisture for the development of blisters.
Although these factors play a part in the development of blisters, blisters are actually caused by a force called shear.
What REALLY Causes Blisters.
Shear forces cause horizontal movement of the layers of the soft tissues between the bones and the outermost layer of the skin.
High shear forces break the connective tissues that hold these layers together.
When these tissues break, fluid fills the space created which, with continued shear, forms the familiar bubble-like skin lesion that we all know as a blister.
Let’s do an experiment to help further explain this; place your fingertip on the back of your other hand.
Rub and slide your fingertip backwards and forwards over the skin.
This is friction.
Now, hold your fingertip on the same position on the skin, move the skin backwards and forwards under your fingertip without losing contact with the skin.
In this situation, the skin under your finger moves but your finger does not lose contact.
The force you have created here is shear.
In the feet, shear forces can be especially high between any contact point (shoe or ground surface) and any bony prominence such as under the balls of the feet and about the heel and knuckle joints of the toes.
Four Factors That Affect Blister Formation
1. Type of Skin
The skin on the feet is thicker and less mobile than other skin which allows it to form and maintain a blister better.
Also, some people have a greater shear strength in their skin than others making them more resistant to blister formation.
2. A High Coefficient of Friction
The coefficient of friction of a substance refers to how “grippy” it is.
A slippery substance like ice has a low coefficient of friction while rubber, for example, has a much higher one.
Skin that is moist and warm has a much higher coefficient of friction than dry, cool skin and as such, grips the sock or shoe more tightly which will, in turn, increase shear forces in the skin.
3. Moving Bone
Every time our feet hit the ground, the skin grips the ground but the bones in our feet continue to move inside the skin.
This creates shear between the tissues held in place by the ground/ shoe and the moving bone.
The more often skin is subjected to shear force, the more likely a blister is to form.
For some people, this may be a few steps while for others, it may take many, many steps. Everyone is different.
Prevention and treatment of blisters should aim to reduce the amount of shear force at the blister site.
Good fitting footwear can help prevent blisters
Footwear to Prevent Blisters
What you put on your feet is the most important part of reducing your blister risk.
A shoe that does not fit well or that is not laced appropriately will increase the movement of the bones in the feet and subsequently shear.
Shoes also need adequate ventilation to help to reduce moisture about the feet and reduce the “grippy-ness” of the skin.
Socks - Moisture-wicking socks draw moisture away from the skin and also help to reduce the grip of the skin.
Tape and paddings aim to reduce the friction between the shoe and the skin to reduce shear forces.
Padding can also be strategically placed around a blister that has formed to make it more comfortable.
Engo Patches are an in-shoe adhesive patch that is thin and have a very low coefficient of friction.
They are long-lasting and can really reduce shear forces about blister hot-spots.
Change the Way You Move
The way we move is a very individual thing.
There is no right or wrong way to move, just your way.
Biomechanical problems can cause an increase in bone movement inside the skin and help to build up shear forces.
Orthoses inside the shoes are an excellent way of changing the forces that cause certain foot movements.
If your heel bone is moving excessively and causing shear at the heel, orthoses can reduce this movement and help prevent blisters.
Your running and walking technique can also be altered to reduce shear stress on the skin.
Changes to factors like your stride length and your cadence (how many steps you take per minute) can change how your foot hits the ground and reduce shear under bony prominences.
Remember though that any sudden changes to the way you move could just cause problems elsewhere!
Should I Pop A Blister?
If the blister has not popped, I usually recommend padding the area around the blister to reduce pain and attempt to eliminate shear forces as much as possible.
The fluid in the blister may be reabsorbed once the damaged skin has time to heal.
If your blister has popped, the general rule of thumb is to remove any loose skin and treat the raw, exposed skin appropriately with antiseptic and a non-stick dressing.
There are some really great dressings called hydrocolloids that promote rapid skin healing while protecting damages tissues.
We Are Here To Help
If you are regularly experiencing blisters, the first thing to do is book an appointment with one of the Podiatrists at Complete Podiatry for a comprehensive assessment to identify what is causing your blisters to develop.
Once this is done, we will develop a structured management plan that outlines our best advice for how to stop your blisters from forming.
I'm so confident we can help with your blisters that I'd love to chat with you personally, it's what I'm passionate about!
Director of Complete Podiatry