Both novice and experienced runners can experience blisters from the strain running puts on their feet. While it is important to focus on finding the right footwear with proper traction and support, it is also crucial to think about how your feet move in the shoes, the surface you will be running on, and the environmental conditions you may face. Running through snow, creeks, or in the rain can cause wet feet, which can eventually lead to macerations and blisters. If blisters form early on in a lengthy workout or race, they can significantly impact performance.
How Blisters Stop Runners in Their Tracks
When your foot is damaged, it affects the entire kinetic chain from the ankle to the knee and through the hip, thus hindering your forward propulsion. Although you might be able to continue walking with a blistered foot, the altered biomechanics will likely have consequences over time, exacerbating the issues you are already dealing with.
The blister is often not the ultimate cause of a did not finish (DNF) in many cases. Instead, the blister begins the process by altering your running style, and over time these alterations result in additional biomechanical problems. These problems in turn slow you down, disrupt your nutritional strategy, prolong exposure to the elements, and so on. However, it is possible to avoid this outcome. Through training, prevention, knowledge on how to treat blisters, and improved race day management, blisters can largely be prevented. Treating blisters is relatively simple and only requires a few basic products and skills to resolve most issues. Although it may require practice, the effort is worthwhile.
Preventing and Treating Blisters
Causing damage occurs when you exert excessive pressure on an organ or structure in your body. Ultramarathons are typically more challenging and longer than your regular training runs. Additionally, these events usually take place in locations different from your usual training grounds, which means the trail conditions, such as surface, camber, dirt, dust, and debris your feet encounter, are likely to be unlike what you’re accustomed to at home. Moreover, the biomechanics of your feet are influenced by the specific characteristics of the trails, leading to different areas of the foot being subjected to stress. Hence, the combination of shoe, sock, powder, tape, lubricant, and insole that worked during training may not always be effective during the race.
Training on flat ground alone will not adequately prepare you for a mountainous ultra race, just as training on your familiar trails may not fully ready your feet for the challenges of the actual race. To guarantee that your diligent training does not go to waste due to foot problems on race day, it is crucial to employ a comprehensive approach that includes education, preventative measures, and the ability to properly care for wounds.
Understanding the Causes
Blisters commonly arise as a result of friction on the skin, which can be caused by the rubbing of clothing, shoes, or other sports equipment against the outer layer of the skin. This can be aggravated by warm and moist conditions. Over time, prolonged friction can lead to the separation of the upper layer of skin, known as the epidermis, from the middle layer, called the dermis. As a result, a gap is formed and filled with fluid, thus forming a blister. In most cases, this fluid is harmless and free from bacteria, but there is a possibility for infected blisters to contain pus, and traumatic blisters may contain blood. Blisters actually serve as a protective mechanism for the affected area; the pain sensation acts as a deterrent to prevent further injury, and the fluid creates a cushioning effect. However, often we are required to continue our activities despite the blister, necessitating the need for treatment.
Science of Blister Formation
Start with friction
A blister, which runners often call a blister, is officially known as a friction blister because friction is the primary cause. While heat and moisture also play a role, it is friction and the underlying shear forces that ultimately lead to the formation of blisters. When your foot hits the ground, the ground exerts pressure on your shoe, which in turn pushes against your sock, and your sock then pushes against your skin. As you push off the ground, these forces between your skin and sock, sock and insole, and shoe and ground all change direction.
The issue lies in the fact that the surface of your skin is flexible, which is why it is referred to as soft tissue. When your body exerts shear forces, your soft tissue (the skin on your feet) moves more than your rigid bone structure. This misalignment in movement between your skeleton, soft tissue, sock/shoe, and shoe/ground is what ultimately generates the frictional force resulting in a blister. Your shoe and sock cause more movement against the outer layer of your skin (epidermis) than the outer layer of your skin moves against the inner layer (dermis).
As the friction between these two layers of skin persists, the layers eventually come apart. When this separation happens, fluid enters the empty space due to hydrostatic pressure. Consequently, a fluid-filled sac forms between the newly separated skin layers, with the yet-to-be separated layers serving as borders along the edges.
Add Heat and Moisture
Blister formation worsens with the addition of heat and moisture. Heat primarily works by weakening the bond between the dermis and epidermis, thereby speeding up the blistering process. Studies have shown that a 4°C increase in skin temperature leads to a 50 percent acceleration in blister formation (Kiistala 1972). Various factors contribute to the heat inside your shoes, including increases in foot skin temperature, environmental heat, metabolic response, and frictional forces. Moreover, the higher the temperature of your feet, the more they perspire. As a result, your socks, shoes, and skin become more saturated with sweat.
Dumping water on your head, running through a river crossing, and running in the rain all have the same effect (excuse the pun) of increasing the moisture in your shoe, sock, and on the skin of your foot. As a result, this moisture enhances the frictional forces between your foot and sock with each step, thus increasing the likelihood of getting blisters (Naylor 1955). Additionally, the moisture also weakens the outer layer of skin, making it more susceptible to injuries.
And complicate with hydration status
Your skin is being attacked externally by heat, trauma, and moisture. Additionally, your hydration status internally can also influence your susceptibility to blisters. When a runner becomes slightly hyponatremic (having low blood sodium), the body’s protective response is to draw water out of the plasma into the extracellular space. This increases the sodium concentration in the blood. Due to gravity, the fluid in the extracellular space accumulates in the extremities, often leading to swollen hands or feet.
Unlike your hands, which are not subject to the rigors of propelling you forward, your feet experience these challenges. The additional fluid in the extracellular space of the skin on your feet speeds up the formation of blisters. Consequently, your feet expand, transforming your previously well-worn shoes into a source of friction. Moreover, the fluid causes the skin layers to become more separated, as it can effortlessly pass between the dermis and epidermis.
Prevention is the Best Cure
The most effective approach to address blisters is to avoid getting them altogether. To avoid blisters, it is necessary to reduce friction on the skin. Approaches for preventing blisters consist of:
- Inspect your feet daily and identify any “hot spots.” If you develop any hot spots during activity, it’s important to treat them right away to prevent the blister from forming. Compeed have a range of products suitable for protecting and soothing your feet. With specialized plasters for every part of the foot, it’s really useful to keep some in your pocket for immediate treatment of hot spots or blisters during a run.
- Break in” your footwear. Competing in new shoes that have not been previously worn will lead to blisters. Make sure the shoe fits properly to avoid excessive movement and can adapt to any swelling that might occur over the course of a race.
- Use moisture-wicking socks to reduce friction and moisture on the skin of the feet. Toe socks like Injinji provide an added layer of protection for the toes and are designed to provide superior moisture management when compared to normal socks. Another brand to consider is Drymax which, as their name suggest, has developed a range of socks specifically designed to keep your feet as dry as possible whilst running. With a range of features to stop dirt getting inside your socks and flat toe seams, they are very popular amongst runners.
- Consider using a lubricant every day. Lubricants can reduce friction and limit moisture that can lead to skin breakdown. An example would be Bodyglide, an easy to apply balm that is resistant to perspiration and water. These products stand-up to heat, humidity and cold. They help lubricate dry skin, prevent hotspots and can last for hours, making a big difference in preventing blisters when it comes to race day.
- Tape your feet or toes. A thin paper tape, such as hydropore, around each toe can last for days. However, make sure you avoid taping between the toes, as this is likely to cause friction. Stronger tape, such as moleskin and Elasticon, along the base of the foot or heel can also come in handy.
Advice for Treating Blisters
If you happen to get a blister, the objective is to stop it from getting bigger and to avoid infection. Various treatment choices are available.
- Small unbroken blisters that don’t cause discomfort should be left to heal on their own; the best protection against infection is your own skin.
- The effects of many early or small blisters, as well as significant hot spots, can be diminished by adding a layer of tape over the area or surrounding them with a donut-shaped piece of moleskin to help relieve local pressure.
- Large, painful blisters that are not bloody can be drained with every effort made to preserve the top layer of skin covering the blister. To safely drain a blister, clean the blister and the surrounding area with rubbing alcohol or antibiotic soap and water. Next, sterilize a needle over a flame until the tip glows red and allow it to cool. Finally, puncture a very small hole at the base edge of the blister and drain the fluid by applying gentle pressure. Once drained, cover with a bandage. If it looks potentially infected, you could use an antibiotic ointment. Seek medical attention if there is progressive redness or foul smelling discharge from the blister.
Top Tips for Preventing / Dealing with Blisters Before, During and After a Trail Race
Pre-Race
To reduce calluses, it is recommended to maintain soft skin rather than having hard calluses. Common areas where calluses tend to form are under toes, on the heels, and on the bottom and side of the forefoot. If a blister develops underneath a callus during a race, it can negatively impact your performance since it is extremely difficult to drain and can cause significant pain. To prevent such issues, it is advisable to use a callus file and lotion to effectively manage the formation of calluses.
Before you go hiking, make sure you know how to treat blisters and how to tape your feet.
During the Race
Make sure to put on socks that are specifically made to decrease moisture around your feet. If you are going to be in sandy conditions, it’s best to not wear double-layer socks since sand can accumulate between the layers of the socks.
It is important to have a small blister kit, such as The Essential Blister Kit from The Rough Country, and be familiar with its usage. This kit, contained in a plastic Zip-Lock bag, includes all necessary items to keep it dry and easily accessible while on the trails. The Rough Country Essential Blister Kit includes a detailed instruction guide on foot care during the race, ensuring that you have everything necessary without unnecessary weight in your pack.
After the Race
In preparation for a race the following day, it is important to allow your feet to breathe, inspect and address any areas of irritation or blisters, and ensure your shoes are cleaned.
If the race has ended, you should soak your feet in Epsom Salts and warm water up to four times daily. The drying effect of the salts facilitates a quicker healing process for blisters.
Many runners and athletes fail to consider the importance of preparing their feet for a competition, whether it is a race where you have a chance of winning or a casual day out with friends. It is crucial to give attention to your feet, as they are your most valuable asset.
