This is a guest post by podiatrist Rebecca Rushton from Australia. She has looked at blisters, how they are formed, what causes them, and how to prevent them. For years, the common thinking about blister causes has been friction, heat, and moisture. Rebecca’s research has led her to identify shear as a leading cause of blisters. Read the article and then check out her website. Over the next months, Rebecca and I will take an in-depth look into blisters, their formation, and treatments. Her website Blister Prevention has a lot of valuable information on blisters (more on that at the end of this post). Here’s Rebecca’s article.
An Introduction to Shear and Blister Formation
Foot blisters continue to wreak havoc with endurance athletes’ feet in spite of their best preventative efforts.
Poor blister prevention outcomes are due in no small part to the misunderstanding of the cause of this obstinate injury.
The force that causes ‘friction’ blisters is not friction. And it’s not rubbing. It’s shear. But if you ask 100 people the question “what causes blisters”, nobody would answer “shear”.
Shear is the sliding of layers across one another – internal layers that are structurally connected. Those connections can break and when fluid fills that cavity, you have a blister!
What Does Shear Look Like? Try this …
Step 1: Place the tip of your right index finger on the back of your left hand.
Step 2: Wobble it back and forth but keep it stuck to the same bit of skin. Notice how your skin stretches? This is shear and this is what causes blisters.
Shear might look like rubbing but it’s not. Notice how your finger tip has not moved relative to the skin of the back of your hand? But your hand skin has moved relative to the underlying bone. This is shear. Your skin doesn’t need anything to rub over it for blisters to form. It just needs shear (this stretching of the internal tissue layers) to be excessive and repetitive.
Rubbing Causes Abrasions
Most of us use the term rubbing to mean two surfaces moving across one another – like when you rub your hands together. The type of skin injury that rubbing causes is abrasions. An abrasion is where the top layers of skin are rubbed off – you end up with a red raw sore. Blisters (from shear) and abrasions (from rubbing) are completely different entities – they have different mechanisms of injury and affect different layers of the skin. Here’s a video on blisters versus abrasions on the feet.
Is the distinction important? Yes it is. The lack of understanding of blister causation is at the heart of why foot blisters continue to plague athletes.
Achieving True Blister Prevention Success
There are 3 factors that influence shear. Impacting on these is how we can minimise shear and prevent blisters.
1) Type of skin
Thinner and more mobile skin (like we saw earlier on the back of the hand) will abrade before it blisters. In contrast, thicker and less mobile skin (like on the palm of your hand) is the type of skin more likely to form and maintain a blister. Do the same experiment we did before but with your index finger on your palm – the skin is noticeably thicker and less mobile in comparison. (This is why blisters are most common on the soles and palms)!
Apart from the thickness and mobility characteristics which determine the ability to blister (and which you can’t do an awful lot about), shear is influenced by two other factors: friction and bone movement. You need both, not just one, to create skin shear. The good news is that these things we really can change! Change one or more of these, in one of many ways, and you can successfully prevent foot blisters.
Friction is the force that resists the movement of one surface against another. It’s the degree of slip or grip between surfaces. Low friction (slippery) is when two surfaces glide easily against each other. High friction (sticky) is when the two surfaces tend to grip together.
The moist in-shoe environment during exercise causes high friction levels between the shoe, sock and skin. This causes these materials to stick together … yes the shoe sticks to the sock and the sock sticks to the skin … for longer. They all stick together for longer because of high friction.
3) Bone Movement
Meanwhile, as we run the bones move back and forth. With the skin remaining stationary (for longer) and the bones moving back and forth as far as they can go, the soft tissue in between stretches – that’s what shear is.
This concept of friction and bone movement leading to shear is depicted in the diagram below and in this video demonstrating shear.
The purple area is a section soft tissue between the skin surface and its underlying bone. Although the heel itself has not lifted within the shoe due to high friction levels, the bone has moved up relative to the skin surface causing shear to the soft tissues in between.
Rebecca’s website Blister Prevention has a lot of valuable tips and techniques, and information on blisters. Take some time and explore the site, subscribe to updates and receive a copy of her ebook, Blister Prevention for Active People. Rebecca is a podiatrist in Australia.
Next Up? More on Shear and Blister Treatments
Over the next month or two, we will talk more about shear and common blister treatments – including what works and doesn’t work. Make sure you are a subscriber to this blog to receive each post. You can do that at the box at the upper right side of this page.
Today’s post is long, but illustrates a valuable point. The Facebook post below started a long chain of responses – all suggestions on what the poster could do to eliminate her blister problem. There were a total of 64 responses. Let’s get right to what was initially posted.
Original Facebook Post
So some of you may remember the nasty blood blister I got during Boston in 2011. I am very unhappy to say I have another one as a result of yesterday. Today I will be doing a GREAT amount of reading on not only how to treat but prevent this from happening again. My next long run is 20 miles. I think that moleskin is going to become my new best friend for EVERY long run.
I use Sportslick and only wear Wright socks (thin, double layer) for long runs. For my last Ironman I put anti-perspirant on my feet everyday for a week before the race. I got no blisters. Good luck!
Soldiers have been known to wear panty hose footies during marches. And tape every hot spot.
Going to look up mole skin because since I lost 90+, my sneakers were huge on me and I didn’t realize it so after the bursitis incident I walked a few miles and had horrible blood blisters that were UBER painful. I applied Band-Aids the next day and kept hustling… moleskin eh? Thank you and healing love to your blisters. They hurt!
May be time to re-evaluate your shoes. I got a whopper this summer after a 20 miler. My inserts in that particular pair of shoes were causing me to run a little odd.
Moleskin! I used it with any shoe that pinches or rubs, especially heels. I found cleaning my skin with alcohol first helps it adhere the best and stays even after taking showers!
If you have sweaty feet be warned moleskin can be sweated off. It is probably the best out there though to prevent blister. If it gets rolled or folded it can make the problem worse.
I use Sportslick and wear Wright socks as well. No blisters as of yet. It got me through my first marathon with no blisters and it rained that day and my feet were soaked. It didn’t do much for my bruised toe nails though lately I have been using Monkey Butt” anti-chafing powder when training for triathlons. Have had great results with this product with my bike shorts. But for feet, I would recommend Sportslick as it is a thick petroleum based ointment. Best of luck! And remember, one foot in front of the other. It doesn’t have to get any more complicated than that!
New shoes may also be the answer. I switched from running in Nike Air Pegasus years ago to Mizuno Wave Riders with little to no blistering. Turns out I needed a narrower toe box and the Nike Pegasus toe boxes would stretch a great deal over time.
Research socks and use a Bodyglide type product .
I have hyper mobility in my feet. I was using Sauconys. Horrible foot pain. Got some Mizuno. Best shoes ever! I can run without pain!
I use anti-perspirant and change my socks every 5 miles .
Try Balega dry fit socks. I NEVER get blisters anymore and I’ve completed two marathons and two Ironmans in them. Used to get blisters all of the time before I switched!
Mizunos + Bodyglide + a great fitting pair of socks = No blisters… ever again!
I get the cheap Monistat anti-chafing cream and put that on my blister prone areas, and it works perfect!
My latest blood blister peeled off the end of my toe just this week! I had a little party!
Have you ever tried Smartwool socks? They are pricey, but worth it. I haven’t had a blister since I started wearing them on my runs .
We always wore two thinner pairs of socks in high school if we had history of blisters… one pair inside and it worked like a charm.
Inside out [socks].
Here’s my 2 cents! I keep my toenails as short as I can handle- short! Smear on some Vaseline between my toes wear the same brand of sox and so far so good.
Moleskin is amazing, and glide works well too. I have heard if you’re in a pinch use deodorant where there is any friction.
In the years I have done marathons/half marathons, I find that having the right shoes, using wicking socks (I too use the Wright socks), and use talc/baby powder in between my toes I do not get blisters.
I gave up on running because of constant and ongoing blisters, I tried several shoes etc nothing helped, I loved running but those blisters were so painful, what is moleskin?
Totally agree with Smartwool socks. They rock.
Try Nuskin. I have a friend who is a marathon runner and this company is her sponsor. Supposedly very good!
Love moleskin! I get wicked blisters without it and none with it. The stuff rocks! Superb for healing blisters too!
Military uses just basic slip on panty hose/dress socks especially with long hauls when carrying 80+lbs in the desert – it works and it is cheap.
Mole Skin and my hiking boots = Love.
Panty hose and then socks over?
I swear by these don’t know if you have used/seen them – Nike Elite Anti-Blister Low-Cut Tab Running Socks.
I spray my feet with Trislide if I start getting any rubbing in my shoes. I can run barefoot and not get a blister no matter how long I go.
SUPER HELPFUL! OKAY NOW FOR TREATMENT FOR MY EXISTING BLISTER? IDEAS? I HAVE RUNS THIS WEEK.
There are lacing techniques that you can try to that help prevent this – as with some of the other comments; you may need a different shoe or sock. I’m sorry, that’s such a pain! I recently switched from Saucony to Mizuno’s & have had a really great experience so far.
Try the book Fixing Your Feet by John Vonhof. We ultra runners swear by this book.
Yeah I do believe my Saucony Kinvaras are out for this very reason. Both times I wore them – in Boston and again yesterday it happened.
The best stuff for blister is Compeed. It is now sold by Band-Aid as Blister Band-Aid and still says Compeed on the box. You can put over the blister and still run without feeling anything. I always carry with me on races. Just in case!
To heal the latest blisters I had to pop them as they were so big I couldn’t put shoes on. Then I cut the size of the blister out of the center of the moleskin and place it over/around the blister. Kept blister clean and voila, perfectly fine that night!
Yes – pantyhose and then socks over – they glide and no friction in between skin and toes.
I play hockey and some girls get the worst blisters from skates. It was actually a doctor on our team that recommended using duct tape! It does work better than moleskin and with good socks. This is at the stage where you are getting irritated in a certain spot, not of course after the blister has formed!
I second the double sock and panty hose method. I actually found ones you wear for ballet flats very helpful. Not sure how they would do on long hauls as I was a short and medium distance sprinter. Cheap and easy.
I have ran a ton of marathons and have stopped getting blisters when I purchased a good pair of socks and bought my shoes a size and a half bigger. So one good sock and big shoes = happy feet.
What you are describing sounds like poorly fitted shoes to me. Make sure you get fitted a good running shoe store, and tell them up front that you have a problem area. A good running shoe fitter should be able to fix the problem.
Knee high pantyhose along with powder maybe but the pantyhose should protect your feet from the friction.
You need to check out Incrediwear.com – they have the best socks for runners. My husband does marathons and I’ve recently started running myself. There is no question our feet don’t hurt and they wick away the sweat. They are made with bamboo charcoal and they increase blood circulation.
Wright socks!! I get them sometimes. But I wear Vibram FiveFinger shoes. And any other running shoes I have are minimalist shoes. So not socks… But if you do wear socks. Get some 2-layer Wright” socks! They are awesome. Or an old army trick. Wear nylons/knee highs under socks.
You are not supposed to pop blisters ever. If they pop on their own fine. But I would cover it up with something like the moleskin or a blister Band-Aid and wear good socks and shoes. I like the knee-high panty hose idea. Good luck & feel better!
I hate to hear that girl…I run in Asics, and those socks I told you about and have never had a blister…sorry feel better girl!
I remember that blister because I had an awful one at the same time! I finally stopped getting them when I went to a actual running store, they fitted me with a pair of Sauconys with a wide toe box and laced them just from the middle of the shoe and up. In all the miles I ran after that never got another blister and my black toenails grew out and had no more problems with that either! It’s the wide toe box that saved my feet.
If the blister is open, use vitamin E oil on it at night. Air it out as much as possible. If the blisters are so large you can’t wear shoes, take a cleaned (alcohol) safety pin and drain. Don’t tear skin off. It is best not to pop but sometimes it’s needed. Motrin for the pain may seem extreme but if you r in so much pain and start altering your stride you’ll get even more blisters.
Try Second Skin. It works very good for soldiers. In two days your feet will be like new!
I never got blisters-and i used to run 65 miles a week. My trick was either Thorlo socks, or wearing two pairs of snug socks. And wearing shoes that were a full size larger. My favorites are Kswiss performance. When running distance, your feet swell so much, you need the space to be able to accommodate it.
Vibrams! They literally took away all my feet problems, including blisters. I love them.
Essential oils are helpful for treating the actual blister. Lavender and tea tree (also called Melaleuca) will help it heal. Apply 2-3 drops of each every couple hours – or when you think of it really. I hope it feels better… they are nasty.
I grease my toes and footpad down with simple cocoa butter Vaseline before any run or distance walk! Haven’t had a blister since! Took a couple times to get used to the immediate feel, but now a year later with no blisters, I hardly notice I’m doing it any more! It’s cheap & simple! And, foot fitting socks! I have my favorite kind that I own multiple pairs of, got them at the local Fred Meyer!
I do the same for long runs. And sometimes baby powder to. Helps with the moisture.
After all 54 responses, I had to weigh in. Here’s what I wrote:
As the author of Fixing Your Feet, I’ll comment that some of what has been suggested here is good but some is not what I would recommend. There is no “one right” answer to the ago-old blister problem. There are many causes and many answers. Try some and find what works for your feet. What’s important is fit, socks, trimmed and filed nails, reducing calluses, and a high-quality lube if needed to reduce friction.
Later, I emailed Jenny and based on what she described and the picture of the blister, here is my response to her.
Let’s talk treatment first. Because it’s a blood blister, I’d try to keep the roof intact. If it opens, your circulatory system is open to possible infection. I lance them, but I am used to doing that, and give the athlete a lecture on infection. Generally if you soak your foot in warm/hot water with Epson Slats, several times a day, the blood and fluid will be reabsorbed – and the blister will harden. Over time, after that, the top layer of skin may slough off but by then, the possibility of infection is over. Start there. If the blister ruptures, make sure you use an antibiotic ointment and keep it covered. Signs of infection are redness, heat, swelling, pus, pain, and streaks moving up the foot. That becomes serious. Make sure your Tetanus shot is up to date (usually about every 8-10 years).
As far a prevention goes, here are a few thoughts:
- I think I see the edge of callus at the forward edge of the blister. I don’t like calluses. Try and reduce any you might have.
- Do you have bunions? If so, that changes a few of my ideas.
- I’d guess that you have a shoe issue (meaning fit). If you have wide feet, or the shoes you wear are too narrow, you’ll have these problems. I read you wore the same shoes both time this happened. That’s a good sign you don’t have a good fit. A better fitting shoes could solve your problem. Can you get fitted at a good running store?
- Something else I see is that the bottom edge of the blister is right at the edge of where the insole hits the side of the shoe. This again gets to the issue of fit. There is pressure there, creating friction, that cayses the blister, that builds from this bottom edge upward.
- One option is to protect the area with a strip of tape. Duct tape isn’t the best, but would work. Don’t use white athletic tape. It won’t stick. I prefer Leukotape.
- You could cut a horizontal slit in the side of the shoe over the pressure point.
- I hate moleskin and never use it. It does not stick well, does not conform to the shape of the area, and is too thick. Stick to tape. The ONLY kind I would recommend is Profoot Velvetex Moleskin (available on Amazon).
- Only wear moisture wicking socks.
Something to understand, that I preach all the time, is that what works for one person will not necessarily work for another. That goes for socks, shoes, lubricants, powders, etc. We each are an experiment of one and need to determine what our feet need. Keep me posted.