Blister Care for Ultrarunners: Compeed Under, Leukotape Over

by HARDN

A blister is small. That's the problem. It never feels important enough to stop for, right up until it's the only thing you can think about.

At Western States and Vermont, 40 percent of finishers said blisters hurt their race. By day four of a stage race, three out of four runners have at least one. This isn't bad luck. It's the most predictable injury in the sport, which makes it one of the most preventable.

Two things belong in your drop bag for it: Compeed and Leukotape. One goes on the blister. The other keeps it there.

What a blister actually is

It isn't your sock rubbing on your skin. Most of the rubbing never happens at the surface.

Your skin moves with the sock while the bone underneath doesn't. That shear tears the layers apart just below the surface, and fluid fills the gap. Heat and moisture make the skin softer and easier to tear. That's why blisters show up late, in the heat, after a creek crossing, and almost never in the first ten miles.

That matters for treatment. You aren't trying to make your foot slippery. You're trying to keep the sock and shoe from dragging the outer skin around with them, and to protect the spot that already gave way.

The hot spot is the race

Every blister announces itself first. A warm, rubbed feeling in one spot. That's the hot spot, and it's the cheapest moment you'll get.

Stopping now costs three minutes. Stopping in ten miles costs a lot more, and you'll be dealing with a blister instead of skin.

Almost everyone runs through it. They're at mile 30, the aid station is four miles away, and they don't want to sit down on a rock and untie a shoe. That decision gets made a dozen times a race, and the one time it goes wrong is the one you remember.

Stop. Get the shoe off. Dry the skin. Tape it.

Leukotape: the prevention layer

Leukotape is a rigid tape with an adhesive that's brutally strong. Once it's on, it doesn't move, so it takes the shear instead of your skin. It stays put through sweat, creeks and thirty hours of running in a way most tapes don't.

Use it before the race on the spots that always blister on you. You already know where they are. Use it on a hot spot the moment you feel one.

Putting it on so it stays

• Clean, dry skin. No lotion, no lube, no sweat. Wipe with alcohol if you have it. Tincture of benzoin underneath makes it grip even harder.
• Round the corners. Square corners catch on the sock and peel. Cut every corner round.
• No wrinkles, no stretch. Lay it on flat. A wrinkle is a new ridge for the sock to rub against. Stretched tape pulls at the skin for hours.
• Press it in. Hold your hand over it for thirty seconds. The adhesive needs the heat to set.
• A little lube on top. Not under. Over the finished tape, to help the sock slide over the edges.

To be honest about the evidence: the tape with an actual trial behind it is plain paper tape, which cut blisters by about 40 percent in stage-race runners. Leukotape hasn't been studied that way. It's what a lot of runners and medics carry because it simply stays on, and a tape that's peeled off by mile 20 isn't protecting anything.

The one rule

Never put Leukotape straight onto a blister. The adhesive is strong enough to rip the roof off when it comes off, and the roof is the best dressing you have. That's where Compeed comes in.

Compeed: the blister layer

Compeed is a hydrocolloid pad. It soaks up fluid, turns into a soft gel and cushions the spot, and it sticks to the skin around the blister instead of to the blister itself. It works on an intact blister and on one whose roof has already torn.

Its weakness is exactly the conditions of an ultra. Heat and sweat make it soft, and a soft pad inside a sock slides. On its own it often ends up balled in the toe of your sock by the next aid station.

What didn't work: toe caps

Gel toe caps look like the obvious fix. We tried them. They didn't work.

On paper they make sense: a cushioned sleeve over the toe that hurts. In practice they add bulk to a toe box that's already getting tighter as your feet swell, so the toe has less room than before. They shift and bunch inside the sock. They trap sweat against skin that's already damaged, which softens it even more. And the edge of the cap becomes a brand-new place to rub.

A cap sits loose over the problem. Compeed and Leukotape stick to the skin and don't move, and that's the whole point. Anything that can move against your skin is just more shear.

The combination

Compeed on the blister. Leukotape over the Compeed, overlapping onto dry skin on every side.

The Compeed protects and cushions the damaged skin. The Leukotape holds the Compeed in place and takes the shear. Neither does the job well alone. Together they get you to the finish.

1. Dry the foot completely. Get dirt and grit off.
2. If the blister is tense and painful, drain it first (below).
3. Warm the Compeed in your hands for a minute so it sticks. Put it on, centered, and press it down.
4. Cover it with Leukotape, rounded corners, extending at least a finger-width past the Compeed on every side.
5. Press the whole thing in. Clean sock. Shoe back on.

Then leave it alone. Don't peel the Compeed to check. It's meant to stay on until it lets go by itself, and pulling it early takes skin with it. After the race, soak your foot and peel the Leukotape slowly, back along the skin, not straight up.

Drain it or leave it

A small blister that doesn't hurt much: leave it. The intact roof is a sterile dressing and nothing you carry beats it.

A tense, painful blister that's going to burst anyway: drain it. You control where it opens instead of letting your shoe decide.

• Clean the skin with an alcohol wipe.
• Use a clean needle or a lancet. Go in at the edge, low, where your foot will push the fluid out.
• Press the fluid out with gauze.
• Leave the roof on. Don't cut it off. It protects the raw skin underneath.
• Compeed over it, then Leukotape.

Blood blisters are different. The blood means the damage went deeper, closer to blood vessels, and opening one in the field raises the risk of infection. Pad and protect it. Don't drain it on the course.

After the race, watch it. Spreading redness, warmth, swelling, pus, or red streaks running up from the spot mean infection. That isn't something to tape over. See a doctor.

Before the start line

Most blister care happens weeks before the race.

• Trim your toenails a few days before, straight across. A long nail jams into the shoe on every descent.
• Shoe fit. Feet swell over a long day. A thumb's width at the toe, and a shoe you've run long in, not one out of the box.
• Socks. Not cotton. That one holds up in the research. Beyond that the evidence is thinner than the marketing. Our sock guide goes through what's actually known.
• Gaiters. Grit in the shoe is sandpaper. Gaiters keep it out.
• Practice taping. Do it on a long training run, not for the first time at mile 50 with cold hands in the dark.
• Dry feet when you can. A sock change after the wet section is worth the minutes.

The kit

Small enough for a vest pocket. A second copy in your drop bags, and one in the crew's box.

• A roll of Leukotape, or strips pre-cut and stuck to wax paper
• Compeed, in a couple of sizes
• Small scissors, or pre-rounded strips so you don't need them
• Alcohol wipes
• A lancet or sterile needle
• A few pieces of gauze
• Lube
• A spare pair of socks

Put it on the gear and drop bag list in HARDN, and on the crew sheet next to the aid station where your feet usually go. A crew that's already holding the Compeed and the tape when you sit down turns a twenty-minute foot repair into five.

The short version

Blisters come from shear, heat and moisture, and they always warn you first. Stop at the hot spot.

Leukotape for prevention, never straight onto a blister. Compeed on the blister, Leukotape over it to hold it in place. Drain only the tense ones, keep the roof, leave blood blisters alone.

Three minutes on a rock at mile 30 is cheaper than every mile after it.

Break free.