Free 16-Week Training Plan for Arc of Attrition by UTMB Arc 100K
Train for a winter coastal ultra: relentless short climbs, mud, wind, and long hours of darkness.
At 82.7 km with 2,708 m of elevation gain, this is an ultra-distance effort that demands careful fueling, pacing, and mental resilience. At 33 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.
Race date: Sat, 23 January 2027Open entry82.7 km · 2,708 m
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Continue Arc of Attrition by UTMB Arc 100K
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I'm preparing for Arc of Attrition by UTMB Arc 100K. Here is the public training preview.
82.7 km · +2,708 m · 113 days to race day
Public preview only; my private routes and schedule changes are not included.
Plan: https://trailsplits.com/races/arc-of-attrition-by-utmb-arc-100k/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 (1h 35m · ~11.1 km · +300 m)
and rehearses the 33 m/km demand of Arc 100K.
Terrain intel
South West Coast Path — cliff-top singletrack with constant short, steep climbs into and out of coves. The 100M gathers 5,507 m over 173 km with almost no flat running and very little runnable track.
Weather & kit
Late January on the Atlantic coast: gales, driving rain, mud, and temperatures near freezing with severe wind chill on exposed cliffs.
What this plan focuses on
Accumulate night hours — most of this race is run in the dark.
Train the repeated 50–100 m cliff climb-and-drop rhythm.
Rehearse cold, wet kit management and hypothermia prevention.
Practise eating and drinking in wind and rain without stopping.
Build ankle and foot resilience for mud and uneven coast path.
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 7h 25m of running.
Fit the plan to your recent training
This schedule opens at 7h 25m of running and 750 m of climbing in week one and peaks at 11h 25m and 2,150 m in a week; the longest planned outing is 5h 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.
Training emphasis: time on feet, fueling, night running, and steady run-walk pacing.
Plan summary
The block begins on 2026-10-05, this coming week.
Duration
16 weeks
Start
2026-10-05
Peak weekly time
11h 25m
Peak weekly vert
2,150 m
Week 1Base Building
7h 25m ·
750 m vert
Mon · 2026-10-05rest
Rest
Effort: Rest
Rest or gentle mobility.
Tue · 2026-10-06hills
Easy hills + uphill strides
1h 35m · 300 m vert · ~11.1 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 · 2026-10-08easy
Easy run
2h 35m · ~21.4 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 · 2026-10-10long
Long run
3h 15m · 450 m vert · ~24 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 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 · 2026-10-15easy
Easy run
2h 45m · ~22.8 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 · 2026-10-17long
Long run
3h 20m · 500 m vert · ~24.3 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 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 · 2026-10-22easy
Easy run
2h 55m · ~24.2 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 · 2026-10-24long
Long run
3h 30m · 575 m vert · ~25.2 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 · 2026-10-29easy
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 · 2026-10-31long
Long run
2h 35m · 475 m vert · ~18.3 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 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 · 2026-11-05easy
Easy run
3h 00m · ~24.9 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 · 2026-11-07long
Long run
3h 40m · 725 m vert · ~25.6 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 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 · 2026-11-12easy
Easy run
3h 15m · ~27 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 · 2026-11-14long
Long run
3h 55m · 775 m vert · ~27.3 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 5 x 8 minutes uphill at a strong, sustainable effort, with 3 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 · 2026-11-19easy
Easy run
3h 20m · ~27.7 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 · 2026-11-21long
Long run
4h 10m · 850 m vert · ~28.9 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 · 2026-11-26easy
Easy run
2h 20m · ~19.4 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 · 2026-11-28long
Long run
3h 00m · 675 m vert · ~20.4 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 5 x 8 minutes uphill at a strong, sustainable effort, with 3 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 · 2026-12-03easy
Easy run
3h 40m · ~30.4 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 · 2026-12-05long
Long run
4h 20m · 1,000 m vert · ~29.3 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 5 x 8 minutes uphill at a strong, sustainable effort, with 3 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 · 2026-12-10easy
Easy run
3h 55m · ~32.5 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 · 2026-12-12long
Long run
4h 35m · 1,050 m vert · ~31 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 12 minutes on familiar, controllable terrain at steady race-specific effort, descending under control for about 10 minutes between climbs, with poles and race kit where you will use them. 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 · 2026-12-17easy
Easy run
4h 05m · ~33.9 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.
Thu · 2026-12-24easy
Easy run
2h 45m · ~22.8 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 3 x 12 minutes on familiar, controllable terrain at steady race-specific effort, descending under control for about 10 minutes between climbs, with poles and race kit where you will use them. 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 · 2026-12-31easy
Easy run
4h 25m · ~36.7 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. 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.
Run the 82.7 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.
Sun · 2027-01-24recovery
Post-race recovery
Effort: Rest or very easy
Prioritize rest, food, fluids and gentle movement; do not schedule a workout by default.
Cutoff check
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target finish time clears the cutoff.
Result
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Exports
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Disclaimer: this plan is general information, not medical advice. Adjust based on fatigue,
experience, and injury history.
About the Arc of Attrition by UTMB Arc 100K course
At 82.7 km with 2,708 m of elevation gain, this is an ultra-distance effort that demands careful fueling, pacing, and mental resilience. At 33 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.
This training plan adapts the 16-week structure specifically for 82.7 km with 2,708 m of elevation gain,
scaling weekly volume and vert targets so your body is ready for race-day demands.
Ultra-distance trail races require a different approach to training than road marathons. Time on feet matters more than pace, and vertical accumulation is as important as distance.
This schedule keeps the longer outings on single days at the selected running frequency and starting load. It also includes regular easier weeks.
Training phases for Arc 100K
The current 16-week schedule has these phases for 82.7 km and 2,708 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 33 m of vertical per kilometer, much of the Arc of Attrition by UTMB Arc 100K 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.