Black Toenails

Audio Transcript

Coach Claire Bartholic: Hi everyone. Welcome to the Runners Connect Run to the Top Extra Kick Podcast. Today’s question comes from Tabitha.

Tabitha: What might be the likely cause for me to be losing lots of toenails? My shoes are super comfortable and don’t feel too big or too small nor do I feel like I’m slipping around in the shoe.

I’m now not only losing the two toe nails I usually lose, but I also lost the one on my baby toe, on my right foot a couple weeks ago and I am now going to lose the nail on the big toe of my left foot. Any thoughts? Thanks.

Claire: Thank you for your question Tabitha. Getting black toenails from running is a very common issue.

Some runners who get black toenails are lucky enough to be pain free while for others it’s quite painful.

According to a 2004 study, the cause of black toenails from running comes from the repeated impact forces that can happen with each step.

Even though you might not consciously feel your foot sliding around in your shoe, simple physics explains why it does happen.

After your shoes initial impact with the ground, there is a moment where your shoe has come to a stop but your foot inside of it has not. Your foot only stops when it contacts the inside of your shoe and that usually happens right on your toenails.

Then, even more impact force on your toenails occur when you push off from the ground, as your toes strike at the ground to lift your leg in the air.

As you implied in your question, shoes that don’t fit properly will make the problem worse, but in your case, that might not quite be the issue.

If your shoe were too tight, there’s not enough room for your foot to slide forward at all which causes a more abrupt impact at your toenails.

If your shoes are too loose, then the shoe ends up pushing down on the top of your nails as you push off the ground.

One thing you didn’t mention Tabitha is how you tie your laces.

Shoes that are laced too tight can compress the toenails causing them to bruise. On the other hand, a shoe that isn’t laced tightly enough will allow your foot to slide too far forward, which will cause your nails to bang against the front of your shoe.

The simplest fix is making sure your lacing your shoes like Goldilocks, not to lose and not too tight.

The next thing to look at is the terrain that you run on. Running a significant amount of time on downhills can cause an increased likelihood of black toenails. As you run downhill, you naturally tend to increase your speed, all the while the impact forces on your feet are going up.

That means that your foot inside of the shoe is building momentum and force with every step and not only that, but think of how your foot is pointed while running downhill.

Your toes are slanted down to the front of your shoe and gravity helps create a ramp for your foot to crash into your shoe with every downhill step.

Another factor is simply long distance running.

Longer runs and longer races obviously are more prone to cause problems with your toenails because every single step that you add, adds additional stress on your nails.

The longer you run especially in warm conditions, the more your feet start to swell. So, those shoes that felt like they fit perfectly on mile two, will be much snugger on mile 22 which increases the impact forces on the toenails.

Typically, the big toe and the next two toes are the most likely to blacken and that’s usually determined by the length of your toes.

Whichever toe happens to be the longest, will hit your shoe first so that’s the one that’s most likely to blacken.

If your second toe is longer than your big toe, your second toe is more likely to blacken than your big toe.

In your case the pinkie toe getting blackened is a little bit unusual. The pinky toe is a relatively uncommon toenail to turn black.

The first place to look is how your feet interact with your shoes, making sure the toe backs is wide enough, but not to roomy.

It could also be due to an acute impact injury such as accidently kicking a rock or a root while running.

One simple step that all runners should do, to prevent a black toenails is to keep your toenails trimmed. You want them to be short and square and not curved and that helps evenly distribute the stress across your nail.

Now if you’re convinced that your condition has nothing to do with your shoes or your laces, there could be some other factors that play.

Some types of fungal infections of the nail can cause a toenail to appear discolored and bruised and you’ll need to be treated by a doctor, preferably a podiatrist to get that cleared up.

In the worst-case scenario, skin cancer or melanoma can appear underneath the toenails causing the nails to appear blackened so be sure to get that checked out at a doctor’s office.

In most cases, however, blacken toe nails are simply annoying and are not cause for too much concern. They typically heal on their own over several months as the new nail grows in.

But again, if yours do not seem typical, it’s best to check in with your physician just to be safe. I hope that helps Tabitha and thanks again for sending in your question.

That’s it for me for today’s episode of the Extra Kick Podcast. If you’d like to send in your question, head to runnersconnect.net/daily.

Have a great run today.