A recent study, published in the Journal of American Podiatric Medical Association, evaluated the incidents, location, pain, and risk factors of blisters seen in ultramarathoners.

Research was conducted at a five-day multi-stage trail running competition. At the end of the each day, data was taken on the frequency of blisters, their location, their severity, and what preventative measures were used among 50 ultramarathon runners.

Findings

• After four days of running, 76% of the runners had developed blisters on their feet. This compared to 34% after day one, 54% after day two, and 72% after day three.
• 65% of the blisters formed on the toes with 16% under the ball of the foot, 14% at the heel, and 5% on the sole.

Preventative Measures Used
There were a number of different preventative measures used by the runners. Twenty of the runners did not use any additional aids except for standard running socks in their shoe. Ten of runners used taping and the remainder used talcum powder, lubricant, antiperspirants, or combination of those.

It is very interesting to note that there was no statistically significant difference between the different prophylactic measures applied and the occurrence of blisters.

Socks
In addition, different types of socks were used. Some runners were cotton, synthetic, combination of cotton and synthetic. Again, in this study, there was no indication of a statistically relevant reduction in blister incidents.

Finally, there was no significant correlation of blisters with age, height, weight, body mass index, shoes size, or weekly training load.

Summary
The study demonstrates that a majority of ultrarunners will likely develop blisters when running a race of greater than one-day duration and standard prophylactic measures do not seem to be effective at preventing blisters.

A Better Option for Preventing Blisters?
Another option to prevent blisters is the use of extremely low friction patches to apply to orthotics, the shoe insole or the shoe itself.

Polytetrafluoroethylene patches (PTFE) have been demonstrated to have the lowest coefficient of friction of any material commonly added to orthotic devices or shoes. If the runner has a specific area on their foot that has been shown to be at risk for blisters, for example an area that has had a previous history of blisters or already has the presence of a callus, localized PTFE patches may be applied to reduce friction in these areas. Given that standard prophylactic measures have not been demonstrated to be effect, PTFE is currently the best likely alternative to help prevent blistering in distance runners.

You can find more information on PTFE here.

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Bernd Volker Scheer, MD, et. al. The Enemy of the Feet: Blisters in Ultraendurance Runners. JAPMA September 2014