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Intermediate

Trail Half Marathon Training Plan

12 weeks to get ready for a 21K on trails, with long mountain runs, hill repeats, strength and cross-training.

12 weeks

Plan length

5h 35m

Peak week

2h 10m

Longest run

1,200 m+

Peak climbing

See the scheduleFind a race

The four phases

Weeks 1–4

Base

Build the habit and your aerobic engine with easy volume, short hills and strength foundations.

Weeks 5–8

Build

Longer mountain days and hill repeats, plus back-to-back runs for ultras: the bulk of the training.

Weeks 9–11

Peak

The biggest weeks: long runs with your race gear and fueling, and sustained climbs at race effort.

Week 12

Taper

Less volume, same rhythm: arrive at the start line rested and sharp.

Week by week

Monday to Sunday. Open a week to see each day; durations are total time.

Adjust your plan

Plan length
Which one should I choose?
Easy runs

Move them to your machine if you are coming back from an injury or want less pounding. The long run and the hills stay running: that is the specific work.

Weekly load

Minutes each week by kind of work. Tap a week to open it.

15% of the time low-impact
RunningLow-impactStrength
14812
BaseBuildPeakTaper
Week 11· Peak week5h 35mRunning 4h 15mLow-impact 50 minStrength 30 min
Mountain dayHillsEasy runStrengthLow-impact aerobicRest
Week 1Base3h 15m · 500 m+
MonRestRest or 20 min of mobility
TueHillsEasy run with 6–8 short uphill strides25 min · 100 m+
WedBike or indoor trainerContinuous zone 2, by heart rate30 min
ThuStrengthSquats, lunges, step-ups and core40 min
FriEasy runEasy, conversational paceOr low-impact: Bike or indoor trainer20 min
SatMountain dayLong trail run with climbing1h · 400 m+
SunEasy runEasy recovery run or hikeOr low-impact: Bike or indoor trainer20 min
Week 2Base3h 35m · 550 m+
MonRestRest or 20 min of mobility
TueHillsEasy run with 6–8 short uphill strides30 min · 100 m+
WedBike or indoor trainerContinuous zone 2, by heart rate30 min
ThuStrengthSquats, lunges, step-ups and core40 min
FriEasy runEasy, conversational paceOr low-impact: Bike or indoor trainer25 min
SatMountain dayLong trail run with climbing1h 05m · 450 m+
SunEasy runEasy recovery run or hikeOr low-impact: Bike or indoor trainer25 min

Unlock weeks 3–12

Sign in for free to see the whole plan day by day, all the way to race day.

Week 3Base3h 50m · 650 m+Week 4BaseEasier week3h 10m · 550 m+Week 5Build4h 20m · 800 m+Week 6Build4h 35m · 850 m+Week 7Build4h 40m · 900 m+Week 8BuildEasier week4h · 750 m+Week 9Peak5h 10m · 1,050 m+Week 10Peak5h 25m · 1,150 m+Week 11Peak5h 35m · 1,200 m+Week 12TaperRace week1h 30m · 100 m+

The training days

Mountain day

Your long run on trails with climbing, the key session of the week. Keep an easy, conversational effort, walk the steep climbs and practise your fueling.

Hills

Uphill work for climbing strength: strides, repeats or sustained climbs depending on the phase. Hard going up, easy coming down.

Easy run

Short, relaxed runs that add volume without fatigue. If you can’t talk, slow down. Being pure aerobic work, you can also do them low-impact on your machine.

Strength

Legs, hips and core: squats, lunges, step-ups and single-leg work that make you stronger on climbs and steadier on descents.

Strength training guide
Low-impact aerobic

Zone 2 aerobic volume without the pounding of running. The bike is only one option: the elliptical, a stair climber, a rowing machine or aqua jogging work too, each for a different goal.

Choose your machine
Rest

A day off or gentle mobility. This is when your body adapts to the training.

How do you do your low-impact aerobic day?

The bike is not the only way to add aerobic volume without impact. Pick the machine you use and the plan adapts every week, or leave it on “By phase” to follow our recommendation.

Go by heart rate. On a machine you are less used to, your muscles tire before your heart: stay in zone 2 by heart rate to make sure the work is really aerobic.

Match it to your goal. For climbing, prioritise the elliptical with resistance and the stair climber; for a break for your joints, the bike and aqua jogging are better.

Upcoming races for this plan

See all races
Oct 2, 2026 · 20KTransJeju by UTMBJeju Island, South KoreaOct 2, 2026 · 20KUltra-Trail des Montagnes du JuraLancrans, Jura, FranceOct 2, 2026 · 21KSalomon Ultra PirineuBagà, Barcelona, SpainOct 3, 2026 · 18KUltra-Trail Guara SomontanoAlquézar, Huesca, SpainOct 8, 2026 · 20KKodiak Ultra Marathons by UTMBBig Bear Lake, California, United StatesOct 10, 2026 · 24KChilegua TrailLa Pared, Pájara, Fuerteventura, Canary Islands, Spain

Gear for your trail half marathon

Picked for the distance from the products we compare.

Salomon Ultra Glide 4
Salomon Ultra Glide 4Shoes
Hoka Challenger 8
Hoka Challenger 8Shoes
NNormal Kjerag 2
NNormal Kjerag 2Shoes
Asics METAFUJI TRAIL 2
Asics METAFUJI TRAIL 2Shoes
Salomon ADV Skin 12
Salomon ADV Skin 12Vest
Maurten Gel 100
Maurten Gel 100Nutrition

Frequently asked questions

How long does it take to train for a trail half marathon?

Plan around 12 weeks if you already run three or four times a week. 8 weeks can work if you are already fit; take 16 if you are building up from less running.

How many hours a week should I train for a trail half marathon?

This plan starts at about 3.5 hours a week and builds to around 6 at its peak, with an easier week every fourth week so your body absorbs the work.

How long should my longest training run be for a trail half marathon?

About 2h 10m on trails with climbing, a few weeks before the race. You don’t need to cover the full distance in training: weekly climbing (up to 1200 m+ at the peak) and consistency matter more.

What cross-training should I do for a trail half marathon?

One low-impact aerobic session a week, in zone 2 by heart rate. Pick it for your goal: the elliptical or a stair climber for climbing-specific work, the bike or aqua jogging to rest your joints, and a rowing machine to strengthen the back, shoulders and core you use on technical descents and with poles.

Do I need strength training for a trail half marathon?

One or two short sessions a week for legs, hips and core make you stronger on climbs, steadier on descents and less prone to injury. The plan keeps them light in the last weeks.

Other training plans

Trail Running Plan for Beginners10K Trail Training Plan25K Trail Training Plan30K Trail Training PlanTrail Marathon Training Plan50K Trail Training Plan50 Mile Training Plan100K Trail Training Plan100 Mile Training Plan

These plans are general guidance for healthy runners. Adapt them to your level and how you feel, and check with a doctor or coach before increasing your training.