What is the most common sports injury?
Ankle sprain, shin splints, knee pain? Nope none of those. The humble blister is by far the most common foot injury sustained by athletes involved in impact sports, in particular endurance sports such as running and hiking. At best they are irritating, at worst they can be show stopping injuries when they burst and become painful and infected, making further progress difficult or impossible.
There is a lot of misinformation and folklore surrounding blisters, but understanding properly what causes them goes a long way to working out a prevention plan. So if you are beset with blisters, read on!
Try this experiment
Place the tip of your finger on a table or similar surface. Push down slightly and try and slide your finger along the table. You can't, because friction is generated between the skin and the surface. However there is movement beneath the skin, as you can see and feel by the movement of your finger against resistance, distorting the skin on the tip of your finger as you rock it backwards and forwards.
It is these shearing stresses beneath the surface of the skin which cause blisters to form, not rubbing on the surface, as is commonly believed.
Now try the same test, but this time place a piece of paper under your finger tip. Now you will be able to slide your finger more easily along the table as you have reduced the friction. This essentially is what a sock will do, providing a friction reducing interface between the foot and the shoe. Now clearly you do not want a complete absence of friction between the foot and the shoe, otherwise the foot would slide around uncontrollably in the shoe and you would have to compensate by clawing your toes to stabilise the foot, fatiguing the foot muscles. The secret is reducing friction enough to reduce excessive shearing stresses which may cause blisters, whilst allowing enough friction to stabilise the foot inside the shoe.
So how can I prevent blisters from happening?
The possible combinations of sock and shoe are almost endless and the solution for preventing blisters is largely a question of trial and error, but here are a few pointers:
- Make sure your shoes are not too big and that they are laced correctly. Bear in mind that your feet will swell over a long distance, taking up more room in the shoe.
- Consider a double skinned sock or even two thin pairs of socks if your existing shoe sock combination is not preventing blisters
- Try Lubricant products such as Glide or Vaseline to reduce friction on persistent blister areas.
- Blister plasters such as Compeed will provide cushioning and protection for existing blisters but may not reduce shearing stresses sufficiently under the skin to prevent new blisters forming.
How can a Podiatrist help?
At Active Podiatry we can help you to identify any risk factors for blistering by checking your footwear. In some cases your blister may need to be lanced with a sterile needle if it is painful to release fluid. You may need a temporary dressing if the blister is infected. Finally if your blister is persistent you may need an orthotic insole to reduce stress on that area of your foot.
I have a small favour to ask you.
I produce these blogs for the benefit of the running community and I want as many runners as possible to benefit from these. It would really help me if you could take a moment to share these articles with your friends on social media and any relevant groups or forums that you may be subscribed to.
Please feel free to post any questions and comments if these blog post raise any issues for you. Thanks from a fellow runner!