Video: What Causes Foot Blisters From Running?
Foot blisters from running are one of the most common yet unreported injuries in sport. At best, running blisters take the fun out of training and reduce performance. At worst, they can cause serious ill-health if not dealt with appropriately. Let’s take a look at what causes foot blisters, and how we can use that knowledge to make our running blister prevention strategies more effective in having a solution for how to prevent blisters.
Athletes know just how important blister prevention is and consider it an essential part of their preparation. Unfortunately, your success in learning how to prevent blisters continues to be rather hit and miss. The purpose of this article is to help you understand what causes blisters and where your opportunities for running blister prevention may lie.
What Causes Foot Blisters from Running?
Most people think friction is what causes foot blisters. But friction is only part of the blister story. Blisters are caused by shear. Shear is the stretching of skin and soft tissues. Too much shear causes micro-tears to occur just under the skin surface. These tears fill with fluid which results in a blister.
The following video does a great job of explaining what causes foot blisters:
Shear is influenced by three things:
- Skin characteristics
Making some areas of the body, and some people, more prone to blisters than others.
- The movement of the bones
The more the bones move relative to the skin, the bigger the chance of shear injury.
Friction is not rubbing. Friction is the force that keeps two surfaces in stationary contact with one another. Foot blisters occur when high friction keeps the shoe, sock and skin stuck to one another while the bones move back and forth causing stretching of the skin and soft tissues in between. This is what causes blisters; shear not rubbing!
Once the cause of blisters is understood it allows for a purposeful approach to how to prevent blisters. The flowchart below identifies factors relevant to blister causation and the opportunities for prevention.
How to Prevent Running Blisters
Pressure is a factor that enables friction to become blister-causing. Therefore cushioning and other methods of pressure reduction, like Sorbothane insoles, Moleskin and silicone gels, can be helpful in preventing running blisters.
But many runners will acknowledge that cushioning alone is not the holy grail of blister prevention. Also the more cushioning you add to your shoe, the tighter it becomes and pressure increases elsewhere. So try cushioning and pressure deflection by all means but be aware it may not be enough.
How to Prevent Blisters: Tapng
Sports tape does not necessarily reduce shear. Very slippery tape like Gaffa Tape might, but traditional brown sports tape is much less likely to provide a solution in how to prevent blisters. Yet sports tape remains a very popular running blister prevention method used by runners. Why?
The answer to the conundrum ‘how to prevent blisters’ is to reduce nasty effects of rubbing: abrasions and chafing. The previous video showed that you do not need rubbing to cause shear (and therefore blisters). But the two often occur at the same time.
When rubbing occurs over a blister, it de-roofs it and you’re left with a red raw sore. Tape provides protection to the skin so that the blister roof is more resistant to rubbing. The blister will still form, but at least the top won’t get rubbed off. There is no doubt that’s a good thing; a de-roofed blister is not only painful but at risk of infection. But sports tape often doesn’t prevent the blister, a fact that many athletes know from bitter experience.
Indiscriminate vs Target Friction Reduction
Friction is necessary to walk and run. Without it, the lack of traction would make the foot slide around too much in the shoe making it difficult to keep your balance. And it would make propulsion all but ineffective. Yet many runners, in their efforts to reduce friction, take it too far with lubricants. Lubricants like Vaseline applied all over the foot has this very effect. Black toenails and bruising are common consequences. Yet, as the lubricant absorbs and disperses over time (after one hour) friction has been found to increase above baseline measures.
There are many runners using lubricants successfully in preventing blisters. If you’re new to this strategy, I would suggest a more targeted approach by applying to problem areas only and for exercise duration of under one hour.
The Shoe-Sock Interface
The most widely used preventative measures focus on the area between the skin and the sock (skin-sock interface). The difficulties here centre mainly on the effect of perspiration; it loosens adhesive products and dilutes preparations applied. Skin irritation is also an issue for some.
The shoe-sock interface is an area that may hold more potential for longer-term blister prevention. ENGO Patches are used in this way. They are self-adhesive patches that stick to the inner shoe surface including insoles, orthotics and inside shoes, not the skin. The friction level when using ENGO is reduced by up to 80%. ENGO patches are used to target high friction at problem areas only whilst maintaining normal friction necessary for efficient gait. They are thin enough to not affect shoe fit (0.38mm); durable enough to last 500km and the low-friction properties are maintained even in moist conditions.
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