Blisters have long been the bane of runners and other athletes alike. Blisters can be very painful and debilitating and they are often not given the proper consideration they deserve. Commonly blisters have been thought to be caused by simply friction and pressure, but more and more the thinking on this has changed.
When treating blisters it is important to understand what a blister actually is. A blister is trauma to the deep layer of skin cells caused by shear between the skin and the underlying bone structures. Shear occurs when there is enough friction between two objects that when a force is applied it moves over the underlying object of less resistance. For example, on a hot day if you try to slide down the seat on a leather couch in your shorts, your skin sticks to the leather and you can only move as much as your skin can stretch and distort. This is distortion within your skin is called shear. A blister occurs when there IS NO sliding between the skin and the sock/shoe instead the sliding occurs between the skin and the bones. Overtime, and particularly with side-to-side foot movements, the shear becomes abnormal and damaging causing the damaged area to fill with fluid. If there IS sliding between the sock/shoe and the skin, this is called an abrasion. Abrasions cause damage to only the top layers of skin and often lead to a red raw wound. This is commonly seen in poor-fitting shoes that allow the foot to move within the shoe.
Now you are probably wondering why it is important to understand the cause of blisters. Well, if we understand why they occur we can prevent blisters and better treat them. The primary goal of blister prevention and treatment should be to establish the underlying cause. Blisters that occur on the back of the heel are often thought to be caused by the heel moving up and down in the shoe. The latest evidence suggests that often heel blistering is actually caused by the heel bone (calcaneus) moving excessively causing the skin to jam between the shoe and the bone. This excessive heel bone movement might be caused by tight calf muscles, a bony prominence or biomechanical issues that can be treated with stretching programs and orthotics.
Taping has long been thought of as the go-to treatment for blistering. In my experience, taping does not work! Taping has no effect on reducing shear or bone movement and does not reduce or deflect pressure under the foot. So why is it still so commonly used? It goes back to my explanation of the difference between blisters and abrasions. Taping prevents abrasions not blisters! It provides a physical barrier to the skin rather than reducing shear.
The main problem in blister management is that often the cause is multi-factorial. Foot moisture management, activity modification and assessing shoe fit properly are all simple strategies to try before a full biomechanical assessment is required. However, if the blistering continues it is important to ascertain the underlying cause of the problem before it becomes debilitating.