Trail Running · Chamonix

🇫🇷Marathon du Mont-Blanc 42 km:
Course Analysis & Race Readiness

41 km with 2272 m of climbing and 2275 m of descent across nine climbs and three descents. A relentless mid-race 712 m ascent flips into a 922 m plunge, making descending the decisive skill.

CourseRecon scores your own training against the descending and durability demands that define Marathon du Mont-Blanc 42 km — the sample analysis below shows exactly how.

41.3 km

Distance

+2,270 m

Vertical Gain

−2,280 m

Total Descent

Jun 27, 2027

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The Course · GPS-Measured

What 43.2 km / 26.8 mi and 2,270 m / 7,450 ft of vertical gain actually look like

Measured from the GPS track: 43.2 km / 26.8 mi and 2,270 m / 7,450 ft of vertical gain. This is the terrain you're signing up for: read it before it reads you.

Course Profile

Terrain summary

Claimed vs GPS-Measured

Claimed · Organizer

41.3km

Distance

+2,470m

Gain

+1.9 km−200 m

GPS-Measured

43.2km

Distance

+2,270m

Gain

Climb & Gradient

+2,270 mTotal Gain

−2,280 mTotal Loss

Gradient Distribution

26%

Flat

≤3% grade

30%

Run-Climb

3–15% up

10%

Steep Climb

>15% up

34%

Descent

downhill

Steepest Sustained Sections

ClimbCRUX

KM 13.5–17.6 · +712 m

+17.6%

Descent

KM 17.6–23.5 · −922 m

-15.5%

Descent

KM 36.3–43.2 · −839 m

-12.2%

Climb

KM 31.3–34.9 · +428 m

+11.8%

Finish & Cutoff Times

What it takes to finish

Reference finish times from past results — use them to set a realistic goal pace.

3h 33m

Winning time

3h 47m

Top 5

3h 55m

Top 10

10h 00m

Back of pack

Based on 2026 results.

What This Race Demands

Four things this course asks of your body

Every course weights the four pillars of mountain-ultra fitness differently. Descending carries 49% of the scoring weight on this course — the terrain makes that the deciding factor.

Weighting shows where readiness is won or lost at this distance — not whether you need each pillar. An aerobic base is a given for a race this long, so it carries little deciding weight even though it's essential — the gaps open on the climbs, descents and the back half.

AerobicSustained engine

Foundational

Sustained effort over 41 km climbing from 1042 m to a 2191 m high point.

ClimbingVertical power

22%

2272 m of gain across nine climbs, including a 712 m, 17.6% grinder.

DescendingEccentric / braking

49%

2275 m of loss over three descents, led by a 922 m, 15.5% drop.

DurabilityLate-race resilience

29%

Late 428 m climb and 839 m final descent test legs after 30 km of accumulated stress.

The Profile in One Line

A steep, high-swinging 41 km where a single 712 m climb tips straight into a 922 m descent.

Aerobic FoundationalClimbing 22%Descending 49%Durability 29%

Here's how CourseRecon reads a course and an athlete

Sample Readiness Analysis

What a readiness result looks like for this course

This is a worked example for a representative strong mountain-ultra athlete — not your score. Connect your own training and the same analysis runs on you.

Sample

OUT OF 100

READY

For a representative strong mountain-ultra athlete

This is a sample — connect your Strava to see your own result.

Pillar Breakdown

Aerobic

The 41 km distance with 2272 m of gain demands steady aerobic output, especially across the 26% flat and 30% runnable-climb terrain where pace holds.

Climbing

Nine climbs totaling 2272 m require repeated efforts, with 10% of the course above 15% grade and one climb gaining 712 m over 5.4 km.

Descending

Three descents lose 2275 m, dominated by a 922 m, 15.5% plunge and a closing 839 m drop; controlled steep downhill running is the defining demand.

Durability

With 34% of the course descending and steep climbs recurring late, quads must survive repeated eccentric loading through the final 839 m descent to the finish.

KM 13.5–17.6

The 712 m Grinder

A 712 m climb averaging 17.6% over 4 km lifts you toward the 2191 m high point. It is the single hardest sustained ascent and sets up the biggest descent.

KM 17.6–23.5

The 922 m Plunge

Immediately after the summit, the course sheds 922 m at 15.5% over 6 km. Legs already taxed from the climb must absorb the steepest, longest descent of the day.

KM 31–43

Late Climb, Final Descent

A 428 m climb at 11.8% precedes a closing 839 m descent at 12.2% over nearly 7 km. Durability decides who holds form to the finish.

That was a sample