If you’re preparing for a desert ultramarathon, there’s a good chance you’ll experience foot blisters. They’re common, sometimes inevitable, but with the right strategies, you can reduce the risk—whichever way your foot lands.
About Me
I’m an expedition podiatrist with a focus on blister prevention and treatment. Over the years, I’ve worked on medical teams at events like the Marathon des Sables (MDS Legendary), the Fire and Ice Ultra in Iceland, London Marathon, and the Great North Run. My daily work includes treating blisters, pressure sores, overuse injuries, sprains, infections, and the kinds of foot issues that can end a race far sooner than you’d choose.
What Are Blisters?
Blisters are fluid-filled sacs that form between the layers of the skin. They’re usually caused by a cocktail of friction, pressure, moisture, bone movement, and—important for runners—a lack of conditioning. A hotspot (the very start of a blister) is uncomfortable; a full-blown blister can become painful, debilitating, or even race-ending, especially if it’s in an area that takes a lot of pressure.
Are Blisters Painful?
Absolutely. Even a small hotspot can make miles miserable. The bigger a blister gets—and the more critical the location—the worse the pain and potential disruption to your race.
Why Forefoot Runners Get Heel Blisters in the Desert
Most forefoot strikers spend the majority of their training running on their balls of their feet and toes, with very little heel contact. That means the skin and soft tissue at the heel aren’t conditioned for impact. In a desert race like the MDS, with endless dunes and long descents, the situation changes: running or walking downhill forces the heels into the sand, suddenly putting a load of pressure on tissue and skin that’s not used to it.
Add in the need to walk (you’ll do a lot more of this in the desert than you expect), and those unprepared heels start to suffer friction and pressure. That’s a recipe for blisters—especially if conditions prevent you from treating them straight away. Infections, pressure sores, and early race exits can soon follow if these aren’t addressed promptly.
Why Heel Strikers Get Blisters on the Balls of Their Feet
Heel strike runners naturally hit the ground in a heel-to-toe action. That works well on flat or rolling terrain, and most long-distance runners fall into this camp. Desert ultras, though, are full of steep ascents and descents. On the uphill’s, your body weight shifts forward to climb, meaning your pressure moves to the balls of your feet—places that might not be used to such workload if you don’t train for it.
This extra pressure can quickly become a hotspot and then a blister. If a blister over the metatarsal heads (balls of your feet) “degloves”—when the top layer comes off—you’re left with delicate skin that usually can’t tolerate the ongoing abuse of multi-day racing. It becomes harder to finish with every step.
How to Prevent Forefoot and Heel Blisters in Desert Running
Forefoot runners
Get used to walking! The best preparation is to include more walking—in every type of terrain, especially hills—into your training. Condition the skin and internal tissues of your heels by mixing walking and running in your sessions. By doing so, the tissues become more prepared before you even get to the desert.
Heel strikers
Train your forefoot! Spend extra time running uphill (and even up and down stairs, wherever possible) to accustom the metatarsal area to pressure. By leaning forward as you climb, your body’s centre of pressure naturally moves to the balls of your feet, preparing that region for the strain of the desert.
There’s a detailed blog on conditioning for desert ultras here:
Other Factors That Can Affect Blister Risk
- Footwear: Fit, build, and profile all matter.
- Socks: Choose moisture-wicking and technical options.
- Bodyweight and Backpack Weight: Heavier loads amplify pressure and friction.
- Insoles: Shock absorption is your friend!
But above all, the most important thing is prevention: condition your skin and tissues before your event.
If you take nothing else from this—begin your preparation early, vary your training to reflect what you’ll face in the desert, and always pay attention to hotspots as soon as they appear. Happy (and hopefully blister-free) running!
Blisterhelp Marathon Des Sables Pilot Studies
About The Author
I’m Lindsey Ebbs, a podiatrist with more than three decades of clinical experience and a passion for working in the world’s toughest endurance events.
