Ultrarunning: Save Your Feet from Blisters, Black Toenails and Athlete’s Foot

February 28, 2012

This article is part of Endurance Planet’s ultrarunning article series. If you have questions, comments or feedback about “Save Your Feet from Blisters, Black Toenails and Athlete’s Foot”, please leave it below in the comments section…

Feet are perfectly designed for running but when it comes to this sport, they will likely get injured. These can range from the simply irritating to the debilitating and excruciatingly painful. Blisters, black toenails and athlete’s foot may not sound like serious foot injuries but they are common enough ailments that you probably won’t find an ultrarunner who hasn’t experienced one or any combination of all three at one point or another.


Friction is the main cause of blisters. Your feet, socks, and shoes’ inner lining are constantly rubbing against each other. There are also a number of contributing factors to blister formation. Among them could be a folded and thus protruding portion in the sock or shoe inner lining, or decreased skin turgor from dehydration which makes the skin fold and rub against each other.

It’s important then to make sure that both socks and shoes are a good fit. That means they’re tight enough to prevent material from bunching up and minimize the movement of your feet inside the shoe. Another preventive solution is to use skin lubricants to lessen the friction. Others prefer a more minimalist approach and just make sure the socks or layers of them are snug. Use of microporous medical tape to wrap and protect the more sensitive areas of your feet can be effective as well. Some ultrarunners are known to use duct tape because they’re more adhesive and won’t likely peel off and bunch up.

Black toenails

If your toes keep bumping against the front end of your running shoe, they’re naturally going to get bruised. What you’re going to see when you decide to replace socks or shoes at an aid station or at the end of the race are black toenails. The usual victims are your longest toes. In a runner with Morton’s foot, that would be the second toe rather than the big one.

Once again, properly fitting shoes are the primary preventive approach. If they’re too loose, you get too much movement. If they’re too tight, especially in the toebox area, this can also cause more bruising. After the race, a frequently reported treatment is to relieve the pressure by draining the blood building up under the toenail. This is going to involve use of a heat sterilized needle and lots of antiseptic.

Athlete’s foot

The thing about athlete’s foot is that it can lead to cracks on the soles of your feet and this in turn can result in various other conditions such as blisters or secondary bacterial infection. As you may know, the fungus that causes this condition thrives in moist environments. So a good method of prevention is to use socks made of moisture wicking fabric. There are trail ultras that will require you to cross a stream or similar terrain that’s unavoidably going to wet your feet. Thus it’s important to have fresh and dry socks and shoes replacements in your drop bag. There are a lot of easily available medication for athlete’s foot, some over-the-counter while others are prescription.


Do you have questions about blisters, black toenails, and athlete’s foot or what you’ve read so far? Do you have any ultrarunning pointers of your own to add? Please leave your feedback, comments and questions below, and we promise we’ll respond.

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