Blister Prevention

Most runners should not get blisters. There are those who are running in situations that make blisters very hard to avoid Badwater but for distances of 50 miles or less, blisters should not be an issue. I suffer from a skin condition called Epidermolysis Bullosa that makes my skin blister easily, so if I can run 100+ miles without blisters, you should be able to! There are a number of approaches to preventing blisters.

1 The unholy trinity of blisters

Three factors work together to cause blisters; heat, moisture and friction. Friction is the biggest cause, but heat and moisture make the situation worse.

2 Shoe Fit

This is the most critical aspect of preventing blisters. If you are getting blisters, this should be the first thing to check. Your shoe should fit without any excess slipping. You can't tighten up a shoe to compensate for being too big. If you get black toenails, or blisters on the ends of your toes, it's probably because your toes are hitting the end of the shoe. Either the shoe is too small, or so lose your feet are slipping forward.

3 Changes in foot size

Remember that losing or gaining body fat can change the size of your feet. Shoes that used to fit you perfectly may not longer fit the same. A more acute problem occurs on longer races when the feet swell up. Having spare shoes that are slightly larger, or thinner socks for later in a race can help with this problem. Of course, getting the fit right is hard, as you can't practice this until your feet are swollen, and different situations may produce differing levels of swelling.

4 Calluses

Calluses are a sign of poor fitting shoes. A callus is a spot that is likely to turn into a blister with longer distances. You can file down a callus and keep is moisturized, but that is a symptomatic approach. The key is to fix the underlying problem, which is normally the fit of your shoes. Note that a callus is a spot that is thickening; the general thickening of the skin due to being barefoot does not tend to cause this problem. The key is to watch out for small areas or spots that have excessively thick skin.

5 Shoe style and quality

A shoe can fit correctly, but cause blisters due to manufacturing problems. A bad seam can rub and cause blisters. A shoe that bends in the wrong place can have a crease that causes a blister as well. Also, check that your insoles do not slip. Some double sided sticky tape between the shoe and the insole can prevent this.

6 Socks

Read about Blister Prevention and Socks

7 Dehydration & Hyponatremia

Dehydration can be a contributor to blisters, as the skin loses some of it's tension (skin turgor) with significant dehydration. However, reduction in skin turgor is generally associated with 6-9% dehydration (excluding glycogen depletion water losses), at which point the dehydration itself should be more of a problem than the blisters. Hyponatremia is a dangerous condition and one of the symptoms is swelling of the hands and feet, which can cause black toenails or blisters. Read up on Practical Hydration and Hydration 101.

8 Lubricants and Powders

To reduce friction, you can use a lubricant on your feet, either a powder or a semi-liquid. A powder can act as both a lubricant and a drying agent, but too much can form clumps if it gets soaked. Here is a partial list of some of the options

• Hydropel helps prevent the skin absorbing moisture and is particularly useful in wet conditions. It does lubricate slightly, but its water repelling powers are its prime attraction.
• SportsShield is similar to Hydropel, both being based on a silicone lubricant (dimethicone). SportsShield is available as a roll on and towelette, whereas Hydropel is dispensed from a toothpaste like tube.
• Vaseline is cheap and can be used in large quantities. This can provide good lubrication, but tends to keep the skin quite moist. It also makes it harder to attach tape if this is required later.
• Aquaphor is quite similar to Vaseline. Though it has different ingredients, I have not found a significant practical difference as a foot lubricant.
• Bodyglide is one of the original products purposefully marketed as a sports lubricant. While effective, it does not seem to last very well, nor does it reduce the friction as much as other products.
• Blister Shield powder is Teflon, which I found helps a bit, but tends to form clumps when wet.
• Zeasorb powder absorbs six times its weight in water, which sounds effective, but water is heavy and powder is light. To absorb the level of sweat put out by a runner, a lot of powder is required, which I've found to be impractical.

See Powders and Lubricants.

9 Maceration

Maceration occurs when the skin becomes soaked with water. Typically the skin has a wrinkled and pale appearance, and is softened. Maceration is likely to lead to blisters, and can be hard to avoid when running in wet or hot, humid conditions. I've found that Hydropel can help delay maceration; apply liberally before the race starts and spend some time rubbing it into the skin so that is is absorbed.

10 Taping

If you have serious problems, it can help to cover the area with tape. Many people recommend duct tape, but it does not breathe, and the adhesive is not very strong when wet for a protracted period. I have found Micropore with tincture of benzoin, which is an adhesive promoter. For more details see Taping

11 Skin Toughening

See Toughening Feet

12 Read the foot care bible

John Vonhof's book 'Fixing your Feet' is invaluable for dealing with blisters. Check out http://www.fixingyourfeet.com/