DOWNHILL SHEAR27,200 FT OF LOSS
Chamonix, France · August · 106 mi
Foot care for Ultra Trail Du Mont-Blanc (UTMB)
UTMB is a descent race with wet feet on top.
Threat matrix
What Ultra Trail Du Mont-Blanc (UTMB) does to feet.
Every line below is computed from published course data or written by PR Run and labeled as such.
- Long valley descentsSustained descents into the valleys punish toes and nail beds. Trim short, file smooth, and pretape if you have a black toenail history.PR Run field call
- Total descent load27,200 ft of cumulative descent. Nail beds and forefoot pay for all of it.Course data
- Hours on feet106 miles inside a 46.5 hour limit. Every hour adds shear, swelling, and sock saturation.Course data
- Downhill shearMile 64 to 76 drops 4,550 ft at 7.2 percent average grade. Toes hit the front of the shoe, heels lift.Course data
- Heat and sweatAugust highs reach 85 degrees F. Sweat saturates socks, skin softens, friction climbs.Course data
- Cold and numb toesLows near 28 degrees F. Wet feet plus cold is how trench foot and numb toes start.Course data
- Technical groundTechnicality 6/10. Rock strikes, side loading, and constant foot correction grind the same spots.Course data
- Night hoursA 46.5 hour window means hours of taping in the dark with cold hands. Practice it that way.Course data
Downhill shear
Where gravity works on your toes.
Sustained descents pulled straight from the elevation profile. Pretape before these, not after.
Heat and moisture
When the shoe stops drying out.
Modeled across the cutoff window from 7 years of race-date weather at points along the course.
- HEATSweat outruns the shoe
- HUMIDNothing dries out
- WETPlan on soaked feet
- COLDNumb toes hide damage
The schedule
Where you sit down and take the shoes off.
Set your goal time. The clocks, the stop plan, and the kit all move together.
- Les HouchesMI 519:47
Eyes only
5 mi since the last stop, cutoff 1.5 h.
- Eyes only. Feel for hot spots through the sock and keep moving.
- Saint-GervaisMI 1322:40
Socks and a look
8 mi since the last stop, 1,950 ft of descent into it, cutoff 3.5 h.
- Socks off. Check the pressure points and swap if the pair is wet.
- Check toes and nail beds. 1,950 ft of descent came into this stop.
- Les ContaminesMI 1900:53
Eyes only
6.3 mi since the last stop, 1,150 ft of descent into it, cutoff 5.5 h.
- Eyes only. Feel for hot spots through the sock and keep moving.
- Les ChapieuxMI 3205:20
Socks and a look
12.4 mi since the last stop, cutoff 10.25 h.
- Socks off. Check the pressure points and swap if the pair is wet.
- CourmayeurMI 5012:00
Shoes off
18.6 mi since the last stop, 3,750 ft of descent into it, cutoff 17.25 h.
- Shoes and socks off. Pat completely dry, fresh socks, powder if the last pair was soaked.
- Check toes and nail beds. 3,750 ft of descent came into this stop.
- Pull the spare pair, tape, and lube from the drop bag before you close it.
- ArnouvazMI 6216:00
Eyes only
11.2 mi since the last stop, 150 ft of descent into it, cutoff 22 h.
- Eyes only. Feel for hot spots through the sock and keep moving.
- La FoulyMI 7019:07
Shoes off
8.7 mi since the last stop, 2,350 ft of descent into it, cutoff 25.75 h, late race, feet already soft.
- Shoes and socks off. Pat completely dry, fresh socks, powder if the last pair was soaked.
- Check toes and nail beds. 2,350 ft of descent came into this stop.
- Hand the crew the checklist. They tape, you drink.
- Champex-LacMI 7822:00
Shoes off
8.1 mi since the last stop, 2,200 ft of descent into it, cutoff 29 h, late race, feet already soft.
- Shoes and socks off. Pat completely dry, fresh socks, powder if the last pair was soaked.
- Check toes and nail beds. 2,200 ft of descent came into this stop.
- Pull the spare pair, tape, and lube from the drop bag before you close it.
- TrientMI 8801:20
Eyes only
9.3 mi since the last stop, cutoff 33.75 h, late race, feet already soft.
- Eyes only. Feel for hot spots through the sock and keep moving.
- VallorcineMI 9403:47
Eyes only
6.8 mi since the last stop, cutoff 37.5 h, late race, feet already soft.
- Eyes only. Feel for hot spots through the sock and keep moving.
- Finish ChamonixMI 10608:00
Socks and a look
11.9 mi since the last stop, cutoff 46.5 h, late race, feet already soft.
- Socks off. Check the pressure points and swap if the pair is wet.
Checked on top of the essentials for Ultra Trail Du Mont-Blanc (UTMB).
Vest / pack
Crew bag
Drop bag
Kit deltas
What Ultra Trail Du Mont-Blanc (UTMB) adds to the standard kit.
- Powder and a moisture barrierSweat is the friction multiplier on this course.
- Pretape for toes and heelsLong descents load the front of the shoe and lift the heel.
- Extra dry socks and a towelCold wet feet break down faster than cold dry feet.
- Light you can tape byTaping in the dark with cold hands is a different skill than taping at your kitchen table.
- Half size up in the crew bagFeet swell over the back half. A tight shoe at midnight ends races.
- Moleskin for pressure pointsRock strikes and side loading build hot spots off the usual map.
Shoes
What survives this course.
Matched on terrain, technicality, and distance. Fit still beats every spec, so try them on a long run first.
Crew
What your crew needs on paper.
Two plates. On the left, the race-specific notes that never make it into the standard script. On the right, the printable card your crew reads at two in the morning under a headlamp.
Race day notes
- The valley descents are long, steep, and runnable, which is exactly what drives toes into the front of the shoe.
- Alpine weather turns over fast. Rain, mud, and cold hands make taping late in the race a real skill.
- There are paved and hard road sections at the valley transitions. Hard surfaces after hours of trail bruise the ball of the foot.
- Educational only. Test every tape, sock, and shoe combination on long runs before race day.
Where you sit down
- CourmayeurMI 50
- La FoulyMI 70
- Champex-LacMI 78
Print card
A single sheet your crew reads at two in the morning: the stop script, the mandatory kit, and the calls that pull the runner. Print it, laminate it, staple it to the drop bag.
Crew foot care card
Station script. Three to eight minutes if organized.
- Runner sits. Shoes and socks off both feet.
- Inspect: hot spots, maceration, nails, blisters.
- Clean with wipe. Pat completely dry. No tape on damp skin.
- Treat hot spots first. Drain blisters only if necessary with clean technique.
- Fresh socks. Relace shoes. Runner stands and tests before leaving.
Mandatory kit
- Leukotape, kinesiology tape, wipes, blister patches, moleskin
- Scissors, nail clippers, lubricant, powder, spare socks (2+)
- Antibiotic ointment, gloves, cohesive wrap, small towel
When to pull runner: spreading redness, loss of feeling, gait collapse, unmanageable pain.
PR Run · pr.run/foot-care
FAQ
Ultra Trail Du Mont-Blanc (UTMB) foot questions.
- 01
How much toe room do I need for UTMB?
About a thumb width standing in your race socks, and consider a half size up for the second night. The descents plus swelling mean the shoe that fit in Chamonix is tight by the time you come back.
- 02
Where should I stop for foot care at Ultra Trail Du Mont-Blanc (UTMB)?
Courmayeur at mile 50.3, La Fouly at mile 70.2, Champex-Lac at mile 78.3. Those stops carry the most ground and descent behind them, so a sock change and a tape check pay for the minutes they cost.
- 03
Which section of Ultra Trail Du Mont-Blanc (UTMB) wrecks feet?
Mile 64 to 76 drops 4,550 ft at 7.2 percent average grade. That is where toes meet the front of the shoe and heels start to lift. Pretape before it, not after.
- 04
How do I keep my feet dry at Ultra Trail Du Mont-Blanc (UTMB)?
August highs reach 85 degrees F. Sweat saturates socks, skin softens, friction climbs. Change socks at every stop you can, run powder or a moisture barrier, and lean forward when you dump water on your head so it misses your shoes.
- 05
Do I need dry socks for the cold sections of Ultra Trail Du Mont-Blanc (UTMB)?
Lows near 28 degrees F. Wet feet plus cold is how trench foot and numb toes start. Put a dry pair in every bag you will see after dark and warm your feet before you tape.
- 06
How many sock changes for Ultra Trail Du Mont-Blanc (UTMB)?
Plan one at every foot stop you have access to, and carry one spare pair beyond that. 106 miles inside 46.5 hours is long enough that dry socks are faster than the five minutes they cost.
- 07
How do I stop blisters at Ultra Trail Du Mont-Blanc (UTMB)?
Start from the biggest threat on this course. 27,200 ft of cumulative descent. Nail beds and forefoot pay for all of it. Fit the shoe with room for swelling, pretape the spots that have blistered on you before, keep grit out, and change socks at every stop you have access to. Blisters come from pressure, friction, and moisture, so remove whichever one this course hands you the most of.
- 08
What foot care kit should I pack for Ultra Trail Du Mont-Blanc (UTMB)?
Beyond the standard kit, this course calls for powder and a moisture barrier, pretape for toes and heels, extra dry socks and a towel, light you can tape by, half size up in the crew bag, moleskin for pressure points. Sweat is the friction multiplier on this course.
- 09
What shoes work for Ultra Trail Du Mont-Blanc (UTMB)?
70% trail / 20% jeep / 10% paved at technicality 6/10 points toward Norda 055, Hoka Mafate X, Hoka Mafate X. Whatever you pick, race it on a long run first and leave room for feet that swell over the back half.
Educational only. Not medical advice. Persistent pain, infection, or numbness: see a podiatrist or sports medicine clinician.
Train for it
Feet get you to the finish. The plan gets you there on the clock.
Foot care is one system on Ultra Trail Du Mont-Blanc (UTMB). Climbs, descents, heat, fueling, and cutoffs are the rest of it.