Original Editor - Kapil Narale
Top Contributors - Kapil Narale, Kim Jackson and Sai Kripa
Introduction[edit | edit source]
While running, the feet are the most injured body part. This probably occurs with overtraining, disregarding any pain, or not practicing self-care/preventative care. Runner's Toe can be described as toenail damage, and would occur when the toe is rubbing against the front of the shoe , or toes are rubbing against each other , especially if the shoe is too small, narrow, or too large and there is space in front for the foot and toes to move. Your toe nail may become stressed if it regularly rubs against or slams against your shoe. As a result, the area under your nail begins to bleed and turn black. This would generally occur especially when running downhill. 
What is Runner's Toe[edit | edit source]
Subungual Hematoma (Runner' Toe) is quite common amongst frequent and long distance runners,   and trail runners.  Runner's toe is a non-severe injury that can most commonly occur to the big toe (hallux) , but can occur to any of the five toes as they experience significant force during running, either due to their size, or positioning within the toe box of the shoe.   It occurs with the repeated force of the nail at the distal aspect of the toe experienced against the toe box of the shoe.  It can be described as the blackening of your toenail when your toe repeatedly hits and rubs against your shoe , or against each other , causing stress on the toenail.  Specifically, the nail plate of the second toe, the periungual areas of the third, fourth, and fifth toes, and the hallux (big toe) experience an increased amount of force during running.  This would lead to bleeding under the toenail, which would give it a black appearance.  When hemorrhage (bleeding) occurs in the nail matrix, it seeps into the nail plate. However, bleeding distal to the lunula seeps the nail bed.  Loss of the toenail can also be experienced by the nail being pushed down into the nailbed, causing it to be bruised and inflamed, thus breaking off. 
Runner's toe can be known as: 
- Runner's Toenail
- Jogger's Toenail
- Tennis Toe
- Subungual Hematoma
With further repetitive force, onycholysis, thickening, or secondary fungal infection of the nail, may occur.  As mentioned, this generally occurs when running downhill  , when the foot is being pushed forward, in the shoe, with each step. Running in hot weather can also cause Runner's Toe. The hot weather can cause your feet to swell, thus increasing the pressure in your shoe. 
Pathomechanics[edit | edit source]
The most frequent cause of black toenails in people is repetitive stress brought on by the mechanics of running. It generally results in bruising or bleeding underneath the toenail in the bed of the toenail because their toes are typically striking somewhere in the shoes, frequently in the front of the shoes. The term "subungual hematoma" is the medical term that describes what is essentially just a blood blister under the nail; "That black color you see is really the dried blood". This microtrauma is the result of pressure, which can be caused by either too-tight socks or shoes that are too tiny and push your toes against the sides of your running shoes. When your foot is being forced forward further with each step when jogging downhill for an extended period of time, this can increase your risk of developing a black toenail. Running in hot weather can also lead to increased shoe pressure since hot weather makes your feet swell. A subungual hematoma may appear as a tiny black patch right after your run, but it might enlarge over the course of the next few days. Your nail plate may separate and become loose due to the drying of the blood, which can result in your toenail actually falling off weeks or even months later.
Other Causes[edit | edit source]
A black toenail can also be a sign of: 
- Fungal Infection
- Chronic Ingrown Toenail
- Benign bone tumor called called subungual exostosis
- Melanonychia striata
- Cancerous tumor
- toe deformities 
The damp feet from sweat, which runner's usually have, can likely cause fungal infections,  especially since fungi thrive in moist environments. 
Cancers and other tumors are rare. 
Other Activities[edit | edit source]
You can also experience Runner's Toe or such symptoms in contact sports, and sports that involve pivoting or rapid start-stop motions, including: 
- Rock Climbing
Repetitive shearing that occurs during activities such as soccer, tennis, or running, can result with bleeding below the nail plate.  In addition, rock climber often wear tight shoes, and they are seen to stick their foot/feet in holes, for support and elevation. Depending on the size and placement, this can cause Runner' Toe. 
With Soccer players, repeatedly kicking the ball can cause stress to their toenails. This would lead to blood leaking from the vessels directly underneath. This can also be caused by kicking the ball too hard with the top of your toe. Soccer players most commonly experience Runner's Toe on their first and second toe. 
Tennis and Squash players can result with damage to their toenail from the continuous moving, shuffling, pivoting, changing directions, and thrusting/rubbing against their shoe, which will cause stress to their toe. 
Symptoms of Runner's Toe[edit | edit source]
Runner's Toe doesn't occur after a single exposure to stress, but rather a repeated prolonged exposure of stress to the toenail from your shoe. 
Symptoms that may be experienced include: 
- Dark red toenail, which would be acute/new damage
- Black toenail, which would be chronic and prolonged/older damage
- Loose toenail , thick brittle nail that will usually fall off 
- Blood blisters
- Pressure under the toenail
- Loss of the toenail, from pressure causing the toenail to lift off the nailbed
- Trouble walking
- Trouble wearing shoes
- Swelling or tenderness under the tip of the toe 
Despite being a painful condition, runner's toe is usually benign. The condition needs to be properly diagnosed between a nail bed injury or an injury of the end (distal part) of the toe for the correct treatment, and to prevent nail plate deformity. Pain from the fluid build up under the nail, and irritation, can hinder the athlete's ability to perform. 
Onychomycosis or subungual malignant melanoma are possible diagnoses of repeated force, though these are different from runner's toe. Melanoma could be a possibility if there is discoloration of the nail on the periungual region, which would be known as Hutchinson's sign. This an be noticed if there is unusual spreading of the pigment, or if there are differing colours wihtin the pigmented area. This should be checked with a biopsy. 
To ensure there is no fracture of the toe, an x-ray should be conducted. 
The more blood under the toenail, the more it will hurt. 
Prevalence of Runner's Toe[edit | edit source]
This can be common in runners training for long distance races. 
It is seen that Men have a higher chance of running injuries, compared to Women. 
A history of previous injury makes a recurring injury more likely. 
The use of Introduction to Orthotics or shoe inserts is linked to a higher risk of injury. 
Potential risk factors for Men are: 
- Running >40 miles per week
- Running between 20 and 29 miles per week
- Having less than 2 years of running experience
- Recommencing running after an extended break/time off
Potential risk factors for Women are: 
- Previous sport injury
- Running on concrete surfaces
- Running between 30 and 39 miles per week
- Wearing the same running shoes beyond 4 to 6 months
Treatment[edit | edit source]
If you notice symptoms, but your toe and nail don't hurt, there may not be anything you need to do. If it has become black, it may stay that way for many months.  Sometimes the best thing you can do is to let the blackened toenail grow out, and remove itself from the nailbed.  The nail and nailbed may fall off on its own, and will grow back.  However, there are cases where the damaged nail may have to be manually removed to properly assess and treat the nail bed.  The lost toenail will take about 6-9 months to completely grow back.  Time is the best treatment. 
Chronic lesions may be managed with rest and a warm water foot bath. 
However, if you do experience pain, and/or you have trouble walking, it is best to see your doctor to rule out any broken toes or such issues.
With the presence of Runner's Toe, a procedure known as Nail Trephination will be carried out.
Nail Trephination is when the pooled blood is drained, by drilling a small hole in the nail with a heated needle or carbon dioxide laser. As a result of the blood collection, the nail may fall off after treatment. The nail may fall off anyhow, but it will grow back. If there was damage to the nail bed, it may be deformed as well. 
If there is no pain, you can continue to run, but need to ensure that the nail is trimmed short, and that you guard against further injury. 
The nail may fall off any time up to 6 months . If, and when, the nail falls off, you want to ensure that you clean the area with soap and water twice a day, and cover it with a bandage for protection while it heals. When it falls of, if it is bleeding, you want to ensure that you apply pressure to it, to control the bleeding. Applying petroleum jelly might be helpful as it is healing, to keep the skin moist. 
Expert/Professional Assistance[edit | edit source]
After draining, if the pain lasts for more than a few days, you may need to see your doctor or podiatrist. 
You may need extra attention if: 
- There is damage to the base of the nail
- A deep cut or laceration is present
- It continues bleeding
- It looks infected
If it is not treated, infection can cause further complications. Ensure to be aware of signs such as: 
- Fluid or pus
- Increased swelling and redness
- Worsening pain
- Red streaks in the skin
- Throbbing or heat in the toe
Prevention[edit | edit source]
Here are some tips to prevents foot injuries, especially Runner's Toe:
- Choose proper fitting running shoes.
Running shoes should be chosen according to running style, running dynamics, and even running terrain. You'd want to make sure your shoes are fitting properly, so they are snug  , with half an inch in front for your big toe.  One thumb width can also be a good indicator.  You would want some space to wiggle your toes.  In other words, the anterior the box should be high and long enough to allow freedom of movement for the toes and some forward freedom of movement of the foot.  You wouldn't want to wear socks that are too thick either, as this may eliminate the space for your toes to move around. Sometimes the best thing to do is try your running socks on with your running shoes, before purchasing the shoes. 
If you have flat feet, you'd want to make sure your shoes are wider to support the middle arch. 
If you have a high arch, you'd want to make sure to have special adjustments, or orthotics on your shoes as well. 
You'd also want to make sure your shoes have a smaller heel-toe drop/offset. You'd want a low height from the heel to the toe, from the back to the front. Your foot won't be as likely to slip forward. 
Check out Shoe Analysis - Basic Anatomy of a Running Shoe, and Shoe Analysis - Fitting a Shoe for more information on running shoes.
- Tie your shoelaces properly
The way you tie your shoelaces can affect the pressure in your foot. You can get the most comfort possible out of your shoes if you tie the shoelaces with a proper lacing technique. The shoelaces should be tight enough to prevent the foot from sliding forward, without acting as a barrier to circulation. 
The way you tie your laces should: 
- Allow for proper blood flow
- Have room for flexibility/moveability of your feet
- Be tight enough to prevent sliding and rubbing
- Prevent the shoes from applying pressure on delicate areas, especially while running
- Keep your heels snug and steady, to avoid ankle sprains
It is recommended to use the Heel-Lock "Runner's Knot" lacing technique. 
- Keeping your toenails trimmed is also a good idea, 
This way your toenails don't easily rub against the front of your shoe.  If they are shorter than the skin surface of your toes, the only thing that'll touch your shoe is your toe. You also want to make sure they're not too short, and without awkward edges, otherwise you may face having ingrown toenails. 
- Wear Moisture-Wicking Socks, instead of wearing no socks. 
If you happen to not wear socks in your running shoes, your damp and wet toes could cause your feet to slide forward into the toe box with more pressure than with walking. Its a good idea to wear proper fitting moisture-wicking socks that will keep your shoes relatively dry, and keep your feet firmly in place.  You'd also want socks that provide enough cushioning between your foot and your shoe, and for your foot to sit comfortably.
- Work on Your Running Technique
Having a proper running technique, picking up your feet, and not sliding them forward, would help to reduce the risk of injury. Although Runner's Toe usually occurs in frequent long-distance runners, it can also occur in less experienced runners who may not be running with a proper technique. 
- Soak your feet in salt water for 5-10 minutes each day
This will help in reducing infection that may lead to, or be caused by Runner's Toe. 
- Use Toe Protectors
These would prevent against any friction between adjacent toes, and between the toes and shoes. These provide great cushioning and protect against any blisters. 
- Slowly Increase Mileage
You don't want to increase you mileage too quickly, especially if you are a less experienced runner. Less experienced runners who increased their mileage by more than 30% over 2 weeks are more likely to experience an injury, than those who increase their mileage by less than 10%. 
In most cases, there are no long-term consequences of having Runner's Toenail.
However, these action will help heal your Runner's Toenail symptoms:
- Decreasing your mileage
- Replacing your running shoes
- Correcting running mechanics that may be enduring more stress on your toes
Media Message[edit | edit source]
Here is a very well explained video of Runner's Toe : 
References[edit | edit source]
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 Healthline. Common Foot Problems of Runners. Available from: https://www.healthline.com/health/runners-feet (accessed 11 July 2022).
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 Run With Strength. Runner's Toe: Preventing and Treating Black Toenails. Available from: https://www.runwithstrength.com/runners-toe/ (accessed 14 July 2022).
- ↑ 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 3.11 3.12 3.13 3.14 Sgobba C. Self. Yes, Running Can Turn Your Toenails Black - Here's How to Deal. Available from: https://www.self.com/story/black-toenails-from-running (accessed 12 July 2022).
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 Scioli M, Sammarco G. J. Managing Toenail Trauma, The Physician and Sportsmedicine. 1992:20 (7):107-111.
- ↑ 5.00 5.01 5.02 5.03 5.04 5.05 5.06 5.07 5.08 5.09 5.10 5.11 5.12 Brennan Dan - JumpStart by WedMD. What to Know About Runner's Toe. Available from: https://www.webmd.com/fitness-exercise/what-to-know-about-runners-toe (accessed 12 July 2022).
- ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.9 Healthline. Runner's Toenail: Badge of Honor or Medical Concern? Available from: https://www.healthline.com/health/running/runners-toenail (Accessed 12 July 2022).
- ↑ 7.00 7.01 7.02 7.03 7.04 7.05 7.06 7.07 7.08 7.09 7.10 7.11 7.12 7.13 Mailer-Savage Erica A, Adams Brian B. Skin manifestations of running. Journal of American Academy of Dermatology. 2006:55:290-301.
- ↑ Self. Yes, Running Can Turn Your Toenails Black. Here’s How to Deal. Available from: https://www.self.com/story/black-toenails-from-running
- ↑ 9.00 9.01 9.02 9.03 9.04 9.05 9.06 9.07 9.08 9.09 9.10 Kercher Mia. Marathon Handbook. 5 Ways t Prevent and Treat Runner's Toe: get Back Running. Available from: https://marathonhandbook.com/runners-toe/ (accessed 12 July 2022).
- ↑ Global Triathlon Network. How To Stop Getting Black Toenails From Running! Available from: https://www.youtube.com/watch?v=mw_KhDyDFKw&ab_channel=GlobalTriathlonNetwork (accessed 14 July 2022).