Free 16-Week Training Plan for Marathon du Mont-Blanc 42K
A marathon beneath the roof of the Alps.
At 43.2 km with 2,387 m of climbing, this distance challenges both endurance and climbing ability without the time-management demands of a full ultra. At 55 m of vertical per kilometer, much of the course is runnable — the plan focuses on building your aerobic cruising speed while preparing you for the steeper sections. The official cutoff is 12 hours, so pace management starts from week one.
Expected race date: Sun, 27 June 2027By draw (lottery)43.2 km · 2,387 mStart: 06:45
Places go by draw. On last edition's dates the draw falls around Wed, 4 November 2026, before this plan starts; check the organizer's page for this year's dates. Train as planned until then.
Use this date as a planning estimate
The organizer has confirmed the event window, but not 42K's detailed start schedule. The plan currently uses the expected distance day.
I'm preparing for Marathon du Mont-Blanc 42K. Here is the public training preview.
43.2 km · +2,387 m · 268 days to race day
Public preview only; my private routes and schedule changes are not included.
Plan: https://trailsplits.com/races/marathon-du-mont-blanc-42k/training-plan?tier=strong-finish&strength=1&strength_track=no-gym&engine=unified&days=3
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Terrain autopilot
Find a matching route near you
We'll look for a loop near you that matches your next run (55 min · ~5.8 km · +275 m)
and rehearses the 55 m/km demand of 42K.
Terrain intel
Mix of valley paths, forest trails, and alpine terrain. The Aiguillette des Posettes climb is long and steep.
Weather & kit
Late June: warm valleys, cool and potentially stormy at altitude.
What this plan focuses on
Mountain marathon pacing: fast early, climb strong.
Sustained climbing beyond 30 km mark.
Technical descents at speed when fatigued.
Heat management in the valley sections.
Race nutrition for 4-7 hours.
Unified race plan · beta
Uses the same load, recovery and taper rules as race discovery, with course-specific climbing only because this course has verified elevation.
Use it for race-effort sessions and race day. Easy runs stay easy whatever the goal; the plan's efforts come from how you run now.
Your starting point
Not stated. The plan assumes a typical starting week for this race and opens at 4h 15m of running.
Fit the plan to your recent training
This schedule opens at 4h 15m of running and 675 m of climbing in week one and peaks at 7h 10m and 1,900 m in a week; the longest planned outing is 3h 00m. These are prescriptions, not proof of readiness.
Adjust this plan
Swap concrete training days, or mark a day done/skipped without changing the race-specific template.
Calendar subscriptions refresh on the calendar app's schedule. This calendar export uses the selected start date and includes weekly summaries and any pre-base sessions. Use Keep this plan above for a fixed copy of the displayed race schedule.
Route-aware workouts
Key sessions include route buttons that deep-link into the Planner with pre-filled distance
+ elevation filters.
16.7 min/km average required. At an easy all-day pace the course takes about 10 h of the 12 h allowed.
Training emphasis: rolling aerobic speed, moderate hill repeats, and disciplined pacing.
Plan summary
The block begins on 2027-03-08, 22 weeks from now.
Duration
16 weeks
Start
2027-03-08
Peak weekly time
7h 10m
Peak weekly vert
1,900 m
Week 1Base Building
4h 15m ·
675 m vert
Mon · 2027-03-08rest
Rest
Effort: Rest
Rest or gentle mobility.
Tue · 2027-03-09hills
Easy hills + uphill strides
55 min · 275 m vert · ~5.8 km
Effort: Easy; strides strong but relaxed
Start with 10 minutes easy on rolling terrain. Then 6 x 20 seconds uphill strides, strong but relaxed, walking back down between them. Finish with at least 10 minutes easy; the rest of the run is easy on the hills.
Effort: Moderate: controlled reps, stop 1–2 short of failure
No-gym Session A: Bulgarian split squat, single-leg RDL, step-ups (bench/stairs), calf raises, side plank. Quality reps; stop well before failure. If 10 reps feels easy, add weight (backpack/water) so the last 2 reps feel challenging. In peak weeks, keep it short and easy.
Thu · 2027-03-11easy
Easy run
1h 35m · ~13.1 km
Effort: Easy
Conversational aerobic running. Keep easy days easy enough to support the key work.
Effort: Moderate: controlled reps, stop 1–2 short of failure
No-gym Session B: step-downs (slow 3–4s), lunges/sit-to-stand, soleus raises, carries (backpack), dead bug. Quality reps; stop well before failure. Keep the slow step-downs at least a day away from a long run; if this session falls the day before or after one, swap them for core work. In peak weeks, keep it short and easy.
Sat · 2027-03-13long
Long run
1h 45m · 400 m vert · ~11.9 km
Effort: Easy
Build relaxed time on feet at conversational effort. Practise the fuel, hydration and kit you intend to use; treat amounts as rehearsal, not a universal prescription.
Start with 10 minutes easy on rolling terrain. Then 6 x 20 seconds uphill strides, strong but relaxed, walking back down between them. Finish with at least 10 minutes easy; the rest of the run is easy on the hills.
Effort: Moderate: controlled reps, stop 1–2 short of failure
No-gym Session A: Bulgarian split squat, single-leg RDL, step-ups (bench/stairs), calf raises, side plank. Quality reps; stop well before failure. If 10 reps feels easy, add weight (backpack/water) so the last 2 reps feel challenging. In peak weeks, keep it short and easy.
Thu · 2027-03-18easy
Easy run
1h 35m · ~13.1 km
Effort: Easy
Conversational aerobic running. Keep easy days easy enough to support the key work.
Effort: Moderate: controlled reps, stop 1–2 short of failure
No-gym Session B: step-downs (slow 3–4s), lunges/sit-to-stand, soleus raises, carries (backpack), dead bug. Quality reps; stop well before failure. Keep the slow step-downs at least a day away from a long run; if this session falls the day before or after one, swap them for core work. In peak weeks, keep it short and easy.
Sat · 2027-03-20long
Long run
1h 55m · 450 m vert · ~12.9 km
Effort: Easy
Build relaxed time on feet at conversational effort. Practise the fuel, hydration and kit you intend to use; treat amounts as rehearsal, not a universal prescription.
Start with 10 minutes easy on rolling terrain. Then 6 x 20 seconds uphill strides, strong but relaxed, walking back down between them. Finish with at least 10 minutes easy; the rest of the run is easy on the hills.
Effort: Moderate: controlled reps, stop 1–2 short of failure
No-gym Session A: Bulgarian split squat, single-leg RDL, step-ups (bench/stairs), calf raises, side plank. Quality reps; stop well before failure. If 10 reps feels easy, add weight (backpack/water) so the last 2 reps feel challenging. In peak weeks, keep it short and easy.
Thu · 2027-03-25easy
Easy run
1h 45m · ~14.5 km
Effort: Easy
Conversational aerobic running. Keep easy days easy enough to support the key work.
Effort: Moderate: controlled reps, stop 1–2 short of failure
No-gym Session B: step-downs (slow 3–4s), lunges/sit-to-stand, soleus raises, carries (backpack), dead bug. Quality reps; stop well before failure. Keep the slow step-downs at least a day away from a long run; if this session falls the day before or after one, swap them for core work. In peak weeks, keep it short and easy.
Sat · 2027-03-27long
Long run
2h 00m · 500 m vert · ~13.3 km
Effort: Easy
Build relaxed time on feet at conversational effort. Practise the fuel, hydration and kit you intend to use; treat amounts as rehearsal, not a universal prescription.
Start with 10 minutes easy. Then 6 x 20 seconds relaxed strides, with 1 minute easy between repeats. Finish with at least 10 minutes easy; any remaining time is easy.
Effort: Moderate: controlled reps, stop 1–2 short of failure
No-gym Session A: Bulgarian split squat, single-leg RDL, step-ups (bench/stairs), calf raises, side plank. Quality reps; stop well before failure. If 10 reps feels easy, add weight (backpack/water) so the last 2 reps feel challenging. In peak weeks, keep it short and easy.
Thu · 2027-04-01easy
Easy run
1h 15m · ~10.4 km
Effort: Easy
Conversational aerobic running. Keep easy days easy enough to support the key work.
Effort: Moderate: controlled reps, stop 1–2 short of failure
No-gym Session B: step-downs (slow 3–4s), lunges/sit-to-stand, soleus raises, carries (backpack), dead bug. Quality reps; stop well before failure. Keep the slow step-downs at least a day away from a long run; if this session falls the day before or after one, swap them for core work. In peak weeks, keep it short and easy.
Sat · 2027-04-03long
Long run
1h 30m · 400 m vert · ~9.8 km
Effort: Easy
Build relaxed time on feet at conversational effort. Practise the fuel, hydration and kit you intend to use; treat amounts as rehearsal, not a universal prescription.
Start with 10 minutes easy on rolling terrain. Then 6 x 20 seconds uphill strides, strong but relaxed, walking back down between them. Finish with at least 10 minutes easy; the rest of the run is easy on the hills.
Effort: Moderate: controlled reps, stop 1–2 short of failure
No-gym Session A: Bulgarian split squat, single-leg RDL, step-ups (bench/stairs), calf raises, side plank. Quality reps; stop well before failure. If 10 reps feels easy, add weight (backpack/water) so the last 2 reps feel challenging. In peak weeks, keep it short and easy.
Thu · 2027-04-08easy
Easy run
1h 50m · ~15.2 km
Effort: Easy
Conversational aerobic running. Keep easy days easy enough to support the key work.
Effort: Moderate: controlled reps, stop 1–2 short of failure
No-gym Session B: step-downs (slow 3–4s), lunges/sit-to-stand, soleus raises, carries (backpack), dead bug. Quality reps; stop well before failure. Keep the slow step-downs at least a day away from a long run; if this session falls the day before or after one, swap them for core work. In peak weeks, keep it short and easy.
Sat · 2027-04-10long
Long run
2h 05m · 625 m vert · ~13.1 km
Effort: Easy
Build relaxed time on feet at conversational effort. Practise the fuel, hydration and kit you intend to use; treat amounts as rehearsal, not a universal prescription.
Start with 10 minutes easy on rolling terrain. Then 6 x 20 seconds uphill strides, strong but relaxed, walking back down between them. Finish with at least 10 minutes easy; the rest of the run is easy on the hills.
Effort: Moderate: controlled reps, stop 1–2 short of failure
No-gym Session A: Bulgarian split squat, single-leg RDL, step-ups (bench/stairs), calf raises, side plank. Quality reps; stop well before failure. If 10 reps feels easy, add weight (backpack/water) so the last 2 reps feel challenging. In peak weeks, keep it short and easy.
Thu · 2027-04-15easy
Easy run
2h 00m · ~16.6 km
Effort: Easy
Conversational aerobic running. Keep easy days easy enough to support the key work.
Effort: Moderate: controlled reps, stop 1–2 short of failure
No-gym Session B: step-downs (slow 3–4s), lunges/sit-to-stand, soleus raises, carries (backpack), dead bug. Quality reps; stop well before failure. Keep the slow step-downs at least a day away from a long run; if this session falls the day before or after one, swap them for core work. In peak weeks, keep it short and easy.
Sat · 2027-04-17long
Long run
2h 20m · 700 m vert · ~14.7 km
Effort: Easy
Build relaxed time on feet at conversational effort. Practise the fuel, hydration and kit you intend to use; treat amounts as rehearsal, not a universal prescription.
Start with 10 minutes easy. Then 4 x 5 minutes uphill at a strong, sustainable effort, with 2 minutes easy between repeats. Finish with at least 10 minutes easy; any remaining time is easy.
Effort: Moderate: controlled reps, stop 1–2 short of failure
No-gym Session A: Bulgarian split squat, single-leg RDL, step-ups (bench/stairs), calf raises, side plank. Quality reps; stop well before failure. If 10 reps feels easy, add weight (backpack/water) so the last 2 reps feel challenging. In peak weeks, keep it short and easy.
Thu · 2027-04-22easy
Easy run
1h 45m · ~14.5 km
Effort: Easy
Conversational aerobic running. Keep easy days easy enough to support the key work.
Effort: Moderate: controlled reps, stop 1–2 short of failure
No-gym Session B: step-downs (slow 3–4s), lunges/sit-to-stand, soleus raises, carries (backpack), dead bug. Quality reps; stop well before failure. Keep the slow step-downs at least a day away from a long run; if this session falls the day before or after one, swap them for core work. In peak weeks, keep it short and easy.
Sat · 2027-04-24long
Long run
2h 30m · 750 m vert · ~15.8 km
Effort: Easy
Build relaxed time on feet at conversational effort. Rehearse race fuelling: about 40 to 80 g of carbohydrate an hour from early on, 400 to 800 ml of fluid an hour depending on heat and sweat, and sodium with it (about 300 to 600 mg an hour). Use what you will carry on race day and adjust to your stomach.
Start with 10 minutes easy. Then 6 x 20 seconds relaxed strides, with 1 minute easy between repeats. Finish with at least 10 minutes easy; any remaining time is easy.
Effort: Moderate: controlled reps, stop 1–2 short of failure
No-gym Session A: Bulgarian split squat, single-leg RDL, step-ups (bench/stairs), calf raises, side plank. Quality reps; stop well before failure. If 10 reps feels easy, add weight (backpack/water) so the last 2 reps feel challenging. In peak weeks, keep it short and easy.
Thu · 2027-04-29easy
Easy run
1h 30m · ~12.5 km
Effort: Easy
Conversational aerobic running. Keep easy days easy enough to support the key work.
Effort: Moderate: controlled reps, stop 1–2 short of failure
No-gym Session B: step-downs (slow 3–4s), lunges/sit-to-stand, soleus raises, carries (backpack), dead bug. Quality reps; stop well before failure. Keep the slow step-downs at least a day away from a long run; if this session falls the day before or after one, swap them for core work. In peak weeks, keep it short and easy.
Sat · 2027-05-01long
Long run
1h 45m · 575 m vert · ~10.7 km
Effort: Easy
Build relaxed time on feet at conversational effort. Practise the fuel, hydration and kit you intend to use; treat amounts as rehearsal, not a universal prescription.
Start with 10 minutes easy. Then 4 x 6 minutes uphill at a strong, sustainable effort, with 2 minutes easy between repeats. Finish with at least 10 minutes easy; any remaining time is easy.
Effort: Moderate: controlled reps, stop 1–2 short of failure
No-gym Session A: Bulgarian split squat, single-leg RDL, step-ups (bench/stairs), calf raises, side plank. Quality reps; stop well before failure. If 10 reps feels easy, add weight (backpack/water) so the last 2 reps feel challenging. In peak weeks, keep it short and easy.
Thu · 2027-05-06easy
Easy run
2h 00m · ~16.6 km
Effort: Easy
Conversational aerobic running. Keep easy days easy enough to support the key work.
Effort: Moderate: controlled reps, stop 1–2 short of failure
No-gym Session B: step-downs (slow 3–4s), lunges/sit-to-stand, soleus raises, carries (backpack), dead bug. Quality reps; stop well before failure. Keep the slow step-downs at least a day away from a long run; if this session falls the day before or after one, swap them for core work. In peak weeks, keep it short and easy.
Sat · 2027-05-08long
Long run
2h 35m · 875 m vert · ~15.6 km
Effort: Easy
Build relaxed time on feet at conversational effort. Rehearse race fuelling: about 40 to 80 g of carbohydrate an hour from early on, 400 to 800 ml of fluid an hour depending on heat and sweat, and sodium with it (about 300 to 600 mg an hour). Use what you will carry on race day and adjust to your stomach.
Start with 10 minutes easy. Then 4 x 7 minutes uphill at a strong, sustainable effort, with 2 minutes easy between repeats. Finish with at least 10 minutes easy; any remaining time is easy.
Effort: Moderate: controlled reps, stop 1–2 short of failure
No-gym Session A: Bulgarian split squat, single-leg RDL, step-ups (bench/stairs), calf raises, side plank. Quality reps; stop well before failure. If 10 reps feels easy, add weight (backpack/water) so the last 2 reps feel challenging. In peak weeks, keep it short and easy.
Thu · 2027-05-13easy
Easy run
2h 05m · ~17.3 km
Effort: Easy
Conversational aerobic running. Keep easy days easy enough to support the key work.
Effort: Moderate: controlled reps, stop 1–2 short of failure
No-gym Session B: step-downs (slow 3–4s), lunges/sit-to-stand, soleus raises, carries (backpack), dead bug. Quality reps; stop well before failure. Keep the slow step-downs at least a day away from a long run; if this session falls the day before or after one, swap them for core work. In peak weeks, keep it short and easy.
Sat · 2027-05-15long
Long run
2h 45m · 925 m vert · ~16.7 km
Effort: Easy
Build relaxed time on feet at conversational effort. Rehearse race fuelling: about 40 to 80 g of carbohydrate an hour from early on, 400 to 800 ml of fluid an hour depending on heat and sweat, and sodium with it (about 300 to 600 mg an hour). Use what you will carry on race day and adjust to your stomach.
Start with 10 minutes easy. Then 3 x 14 minutes on familiar, controllable terrain at a steady to controlled-hard effort, descending under control for about 8 minutes between climbs. Finish with at least 10 minutes easy; any remaining time is easy.
Effort: Moderate: controlled reps, stop 1–2 short of failure
No-gym Session A: Bulgarian split squat, single-leg RDL, step-ups (bench/stairs), calf raises, side plank. Quality reps; stop well before failure. If 10 reps feels easy, add weight (backpack/water) so the last 2 reps feel challenging. In peak weeks, keep it short and easy.
Thu · 2027-05-20easy
Easy run
2h 05m · ~17.3 km
Effort: Easy
Conversational aerobic running. Keep easy days easy enough to support the key work.
Use race-like terrain where practical, but keep the overall effort controlled. Rehearse race fuelling: about 40 to 80 g of carbohydrate an hour from early on, 400 to 800 ml of fluid an hour depending on heat and sweat, and sodium with it (about 300 to 600 mg an hour). Use what you will carry on race day and adjust to your stomach.
Start with 10 minutes easy. Then 6 x 20 seconds relaxed strides, with 1 minute easy between repeats. Finish with at least 10 minutes easy; any remaining time is easy.
Effort: Moderate: controlled reps, stop 1–2 short of failure
No-gym Session A: Bulgarian split squat, single-leg RDL, step-ups (bench/stairs), calf raises, side plank. Quality reps; stop well before failure. If 10 reps feels easy, add weight (backpack/water) so the last 2 reps feel challenging. In peak weeks, keep it short and easy.
Thu · 2027-05-27easy
Easy run
1h 45m · ~14.5 km
Effort: Easy
Conversational aerobic running. Keep easy days easy enough to support the key work.
Use race-like terrain where practical, but keep the overall effort controlled. Practise the fuel, hydration and kit you intend to use; treat amounts as rehearsal, not a universal prescription.
Start with 10 minutes easy. Then 3 x 15 minutes on familiar, controllable terrain at a steady to controlled-hard effort, descending under control for about 8 minutes between climbs. Finish with at least 10 minutes easy; any remaining time is easy.
Effort: Moderate: controlled reps, stop 1–2 short of failure
No-gym Session A: Bulgarian split squat, single-leg RDL, step-ups (bench/stairs), calf raises, side plank. Quality reps; stop well before failure. If 10 reps feels easy, add weight (backpack/water) so the last 2 reps feel challenging. In peak weeks, keep it short and easy.
Thu · 2027-06-03easy
Easy run
2h 15m · ~18.7 km
Effort: Easy
Conversational aerobic running. Keep easy days easy enough to support the key work.
Use race-like terrain where practical, but keep the overall effort controlled. Rehearse race fuelling: about 40 to 80 g of carbohydrate an hour from early on, 400 to 800 ml of fluid an hour depending on heat and sweat, and sodium with it (about 300 to 600 mg an hour). Use what you will carry on race day and adjust to your stomach.
Start with 10 minutes easy. Then 5 x 3 minutes at a strong, sustainable uphill effort, walking back down between them. Finish with at least 10 minutes easy; any remaining time is easy.
Keep this comfortable and finish with plenty in reserve. Practise the fuel, hydration and kit you intend to use; treat amounts as rehearsal, not a universal prescription.
Start with 10 minutes easy. Then 4 x 3 minutes at a strong, sustainable uphill effort, walking back down between them. Finish with at least 10 minutes easy; any remaining time is easy.
Keep this comfortable and finish with plenty in reserve. Practise the fuel, hydration and kit you intend to use; treat amounts as rehearsal, not a universal prescription.
Run the 43.2 km as planned: start controlled and use the fuelling and kit rehearsed in training. Fuelling: about 40 to 80 g of carbohydrate an hour from early on, 400 to 800 ml of fluid an hour depending on heat and sweat, and sodium with it (about 300 to 600 mg an hour). Use what you will carry on race day and adjust to your stomach. Afterwards: rest or walk for several days, then short easy runs only, with no hard running for three to four weeks, longer after a long mountain day.
Cutoff check
If your race has a time limit, this estimates the minimum average pace and whether your
target finish time clears the cutoff.
Result
Min pace: 16.7 min/km
Exports
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Disclaimer: this plan is general information, not medical advice. Adjust based on fatigue,
experience, and injury history.
About the Marathon du Mont-Blanc 42K course
At 43.2 km with 2,387 m of climbing, this distance challenges both endurance and climbing ability without the time-management demands of a full ultra. At 55 m of vertical per kilometer, much of the course is runnable — the plan focuses on building your aerobic cruising speed while preparing you for the steeper sections. The official cutoff is 12 hours, so pace management starts from week one.
This training plan adapts the 16-week structure specifically for 43.2 km with 2,387 m of elevation gain,
scaling weekly volume and vert targets so your body is ready for race-day demands.
This distance sits at the boundary between endurance and speed — long enough to require serious aerobic preparation, but short enough that pace efficiency and descending technique make a real difference.
The plan builds weekly volume progressively while including hill-specific sessions to sharpen climbing and descending rhythm.
Training phases for 42K
The current 16-week schedule has these phases for 43.2 km and 2,387 m of climbing:
Weeks 1–6 — Base Building: Establish consistent aerobic training and introduce course-like terrain gradually.
Weeks 7–10 — Vert Accumulation: Increase course-specific climbing while rehearsing easy effort and fueling.
Weeks 11–13 — Peak Volume: Practise the longest planned outings and race equipment without adding extra sessions.
Weeks 14–15 — Taper: Reduce training load while retaining a small amount of familiar intensity.
Week 16 — Race week: Reduce training and follow the race-day plan.
Pacing a runnable course
At 55 m of vertical per kilometer, much of the Marathon du Mont-Blanc 42K course is runnable.
Training should emphasise aerobic cruising speed — tempo runs on rolling terrain, sustained effort on moderate climbs, and efficient flat-to-uphill transitions.
The biggest risk on a runnable course is starting too fast; practice negative-split long runs to build discipline.