Free 16-Week Training Plan for Zegama-Aizkorri 42K
Zegama is where mountain running legends are forged.
At 42.4 km with 2,661 m of climbing, this distance challenges both endurance and climbing ability without the time-management demands of a full ultra. With 63 m of vertical per kilometer, expect significant hiking sections — training should emphasise power-hiking and efficient descending. The official cutoff is 8 hours, so pace management starts from week one.
Expected race date: Sun, 16 May 2027By draw (lottery)42.4 km · 2,661 mStart: 07:30
Places go by draw. On last edition's dates the draw falls around Fri, 19 February 2027, in week 4 of this plan; 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 not announced the 2027 event date. The plan will move when the official date is published.
I'm preparing for Zegama-Aizkorri 42K. Here is the public training preview.
42.4 km · +2,661 m · 226 days to race day
Public preview only; my private routes and schedule changes are not included.
Plan: https://trailsplits.com/races/zegama-aizkorri-42k/training-plan?tier=strong-finish&strength=1&strength_track=no-gym&engine=unified
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Grip and footwear: the terrain demands aggressive tread.
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 20m of running.
Fit the plan to your recent training
This schedule opens at 4h 20m of running and 850 m of climbing in week one and peaks at 7h 15m and 2,175 m in a week; the longest planned outing is 3h 05m. 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.
11.3 min/km average required. At an easy all-day pace the course takes about 10 h of the 8 h allowed.
That leaves little margin: a bad patch, the weather or an intermediate cutoff can decide the day, and more training buys less time on a course like this than it seems.
Training emphasis: sustained climbing, downhill resilience, and efficient hike-run transitions.
Plan summary
The block begins on 2027-01-25, 16 weeks from now.
Duration
16 weeks
Start
2027-01-25
Peak weekly time
7h 15m
Peak weekly vert
2,175 m
Week 1Base Building
4h 20m ·
850 m vert
Mon · 2027-01-25rest
Rest
Effort: Rest
Rest or gentle mobility.
Tue · 2027-01-26hills
Easy hills + uphill strides
45 min · 300 m vert · ~4.2 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.
Wed · 2027-01-27easy
Easy run
35 min · ~4.8 km
Effort: Easy
Conversational aerobic running. Keep easy days easy enough to support the key work.
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.
Wed · 2027-02-03easy
Easy run
40 min · ~5.5 km
Effort: Easy
Conversational aerobic running. Keep easy days easy enough to support the key work.
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.
Wed · 2027-02-10easy
Easy run
45 min · ~6.2 km
Effort: Easy
Conversational aerobic running. Keep easy days easy enough to support the key work.
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.
Wed · 2027-02-17easy
Easy run
30 min · ~4.2 km
Effort: Easy
Conversational aerobic running. Keep easy days easy enough to support the key work.
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.
Wed · 2027-02-24easy
Easy run
40 min · ~5.5 km
Effort: Easy
Conversational aerobic running. Keep easy days easy enough to support the key work.
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.
Wed · 2027-03-03easy
Easy run
50 min · ~6.9 km
Effort: Easy
Conversational aerobic running. Keep easy days easy enough to support the key work.
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.
Wed · 2027-03-10easy
Easy run
45 min · ~6.2 km
Effort: Easy
Conversational aerobic running. Keep easy days easy enough to support the key work.
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.
Wed · 2027-03-17easy
Easy run
35 min · ~4.8 km
Effort: Easy
Conversational aerobic running. Keep easy days easy enough to support the key work.
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.
Wed · 2027-03-24easy
Easy run
45 min · ~6.2 km
Effort: Easy
Conversational aerobic running. Keep easy days easy enough to support the key work.
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.
Wed · 2027-03-31easy
Easy run
45 min · ~6.2 km
Effort: Easy
Conversational aerobic running. Keep easy days easy enough to support the key work.
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.
Wed · 2027-04-07easy
Easy run
50 min · ~6.9 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.
Wed · 2027-04-14easy
Easy run
45 min · ~6.2 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.
Wed · 2027-04-21easy
Easy run
50 min · ~6.9 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 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.
Start with 10 minutes easy. Then 2 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 42.4 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: 11.3 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 Zegama-Aizkorri 42K course
At 42.4 km with 2,661 m of climbing, this distance challenges both endurance and climbing ability without the time-management demands of a full ultra. With 63 m of vertical per kilometer, expect significant hiking sections — training should emphasise power-hiking and efficient descending. The official cutoff is 8 hours, so pace management starts from week one.
This training plan adapts the 16-week structure specifically for 42.4 km with 2,661 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 42.4 km and 2,661 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.
Preparing for steep terrain
At 63 m of vertical per kilometer, the Zegama-Aizkorri 42K course is significantly steeper than average.
In this plan the uphill sessions and the climb-and-descent rehearsals are where to practise power-hiking (with poles, if you will race with them) and steep, controlled descending, and the strength sessions carry the eccentric work for your quads.
Practice eating and drinking on steep climbs — this is where many runners lose time to nausea and energy dips.