Blisters on the feet are a common problem among runners. They appear as small bubbles on the skin filled with fluid, which can be pus, serum, blood, or lymph. While blisters may not be a serious injury like a fracture, they can be painful and have a serious impact on your sport. If neglected or not treated appropriately, it can lead to severe infection, cellulitis, or even sepsis.

Understanding why blisters occur and how to prevent them can help you a great deal as a runner. 

How are blisters formed?

Blisters are formed when friction causes damage to the skin. Friction may be produced either by rubbing against a surface (for example ill-fitting shoes), heat (burns), extreme cold and dryness, or due to chemicals. When the upper and innermost layers of the skin slide against each other, fluid-filled blisters appear.   

Why do runners have blisters? 

1. Friction due to ill-fitting socks and shoes in runners. The body responds to this friction by separating the top layer of the skin from the bottom, creating a pocket that fills up with fluid. 
2. Trapped heat and moisture due to sweaty feet or weather conditions can soften the skin making it prone to blisters.
3. An increase in body temperature due to metabolic processes, or a rise in atmospheric temperature could contribute to  the formation of blisters  
4. Wet clothes, shoes, and socks as a result of sweating can increase friction between the skin and the gear.

Signs of an infected blister

A blister can get infected very fast if ignored, and can be dangerous if left untreated. A viral or fungal infection from the blister can spread to other areas in no time. The signs of an infected blister are:

1. Increased warmth around the area
2. Foul smell
3. Pus
4. Pain 
5. Swelling
6. Bleeding on touch

Also read: Running Shoes: Your Guide to Getting Started

Treatment 

Blisters can pop up any time, but can be treated easily as well. Here are some guidelines: 

1. It is far easier to treat blisters when they are small and not large or infected
2. Stop putting pressure on the blister immediately
3. Use an antiseptic solution to clean the surface of the blister
4. Puncture it with a sterile needle at the edges, drain the blister keeping its roof intact. The skin on top of the blister acts as a protective barrier and should not be removed
5. Drain the fluid but leave some behind, so as not to detach the roof of the blister. It should allow continuous drainage of the fluid
6. Clean and dry the surface and the surrounding area of the blister
7. Apply an antibiotic cream gently
8. Use a sterile, dry, breathable, loose bandage to cover the area
9. Apply adhesive tape. Make sure not to apply it on skin folds or creases to avoid friction
10. Reduce your physical activity till the blister heals
11. If the blister does not heal within a few days, see your doctor for further treatment. Also, do not try home remedies, if you have diabetes or high blood pressure. Seek medical help.   

How to prevent blisters

Footwear

1. Socks made of moisture-wicking material can reduce friction by absorbing moisture and reducing the friction load on the surface of the foot.
2. Experts recommend replacing your running shoes after around 800km to 1000km of running.
3. Footwear with sole inserts or socks that provide extra padding should help absorb and lessen the impact and friction. Insoles absorb the shear stress and reduce the friction on the overlying skin. So, ensure that your shoes have the right insoles.
4. Shoes have to be the right fit. Too loose or too tight, and blisters can form blisters on the upper surface of the toes.  Generally, shoes that are a half size bigger than normal are right for running, as your feet may swell during training.
5. New shoes can give you blisters when you wear them for the first time and for a longer period of time in the first go. Get used to running in them slowly. To prevent heel blisters, change your shoelace pattern, and heel lock position. Ideally, lock lacing makes use of the top set of eyelets (the two holes that are usually ignored) to get a tighter grip around the top of the shoe and the ankle, which does not allow the heel to slip, and eventually, prevent blisters. 
6. Do not wear new socks without washing them.  The washing helps avoid the friction from a new pair of socks.

Tapes

1. If you are prone to blisters, you could use moleskin or foot tapes on the vulnerable areas of the skin. Make sure tapes that are applied are smooth and not too tight. Usually, people use tapes like Leukotape, a sticky, breathable sports tape, to prevent blisters.

Lubricants

1. Use lubricants on the vulnerable parts like the bony prominences of the feet, which are likely to come in contact with clothing or hard surfaces like handlebars.
2. Do not overuse the lubricant, as too much of it will cause the feet to glide and create more friction.

Foot abnormalities specific shoes

1. If you have any foot abnormalities like bunions or hammertoes, choose shoes, which will be comfortable to walk in or run with these abnormalities.
2. If possible, consult a physician to look for remedies for correcting these problems.

Anti-skid powders

1. Commercially available anti-skid powders help in achieving sweat-free grips over equipment, thus reducing friction injuries and blisters.
2. Talcum powder also works pretty well to reduce the chances of chafing — do not overdo this, however. Stick to a gentle layer of powder on your feet before wearing the socks.

Keep a blister kit handy

It should contain: 

1. Antiseptic solution
2. Gloves
3. Sterile gauze
4. Sterile needle
5. Adhesive tape
6. Lubricant ointment
7. Antiseptic ointment

Taking timely precautions and care would help keep problems like blisters at bay and make your running experience safer and more enjoyable. So, when are you going for your next run?

References
1. Huppin L. What The Research Reveals About Blister Prevention In Ultra Endurance Runners. Podiatry Today. https://www.podiatrytoday.com/blogged/what-research-reveals-about-blister-prevention-ultra-endurance-runners#:~:text=After four days of running,72 percent after day three (accessed Apr 8, 2021).
2. Tucker A. 6 Lacing Hacks to Make Your Running Shoes Way More Comfortable. Self. https://www.self.com/story/lacing-hacks-running-shoes-more-comfortable (accessed Apr 8, 2021).