Experienced 100k or 50 Mile Ultra Training Plan: 20 Weeks

An experienced 100k or 50 mile trail plan runs 20 weeks at five runs a week, peaks at about 11 hours, and builds long runs to 5.5 hours with a back-to-back of up to two hours the next day. It fits runners who have finished at least one ultra and train 6 to 8 hours a week. It is written in time and effort, not pace.

The 20 weeks

Sample plan · 100k / 50 mile trail ultra, experienced

20 weeks, 5 runs a week, peak week 11h 15m, longest run 5h 30m, up to 3000 m of climbing a week for a race with 3000 m. 90 % of the running is easy.

BaseBuildPeakTaper

Week	Time	Key sessions	Long run
1 Base	6h 55m · 1000 m	Easy running only	2h 40m long run
2 Base	7h 09m · 1050 m	Easy running only	2h 50m long run with power hiking
3 Base	7h 33m · 1550 m	Hill repeats: 5 × 3 min I (3 min jog)	3h long run
4 Base, recovery	6h 09m · 1000 m	Long hill intervals: 3 × 6 min T (4 min jog)	2h 20m long run with power hiking
5 Base	8h 24m · 1700 m	Power-hike repeats: 3 × 8 min power hike (4 min jog)	3h 15m long run
6 Base	8h 40m · 1950 m	Hill fartlek: 10 × 90 s I (90 s jog)	3h 35m long run with power hiking
7 Base	9h 16m · 2000 m	Hill repeats: 6 × 3 min I (3 min jog)	3h 50m long run
8 Build, recovery	7h 13m · 1150 m	Long hill intervals: 3 × 6 min T (4 min jog)	3h 30m long run with power hiking
9 Build	9h 58m · 2700 m	Power-hike repeats: 3 × 8 min power hike (4 min jog)	4h 55m long run, steady finish
10 Build	10h 30m · 2800 m	Hill fartlek: 11 × 90 s I (90 s jog)	5h 05m long run with power hiking
11 Build	10h 51m · 2950 m	Hill repeats: 7 × 3 min I (3 min jog)	5h 20m long run, steady finish
12 Build, recovery	8h 27m · 1350 m	Long hill intervals: 3 × 6 min T (4 min jog)	4h 10m long run with power hiking
13 Peak	11h 15m · 3000 m	Power-hike repeats: 3 × 8 min power hike (4 min jog)	5h 30m race rehearsal
14 Peak	11h 15m · 3000 m	Hill fartlek: 13 × 90 s I (90 s jog)	5h 30m long run, steady finish
15 Peak	11h 06m · 3000 m	Hill repeats: 8 × 3 min I (3 min jog)	5h 30m race rehearsal
16 Peak, recovery	8h 39m · 1350 m	Long hill intervals: 3 × 6 min T (4 min jog)	4h 10m long run, steady finish
17 Peak	11h 11m · 3000 m	Power-hike repeats: 4 × 8 min power hike (4 min jog)	5h 30m longest run: race rehearsal
18 Taper	8h 54m · 2000 m	Hill fartlek: 8 × 90 s I (90 s jog)	4h 25m long run
19 Taper	7h · 1400 m	Hill repeats: 5 × 3 min I (3 min jog)	3h 20m long run
20 Taper	1h 17m + race	Race day	None, race week

Open this plan and make it yours →

The sample runner has five days a week and a race with 3,000 m of climbing:

• Base, weeks 1 to 7. 6.9 to 9.3 hours. Long runs from 2 h 40 to 3 h 45. The hill session starts in week 3 and rotates through 3-minute hill repeats, 6-minute hill intervals at threshold, power-hike repeats and hill fartlek.
• Build, weeks 8 to 12. 10 to 10.9 hours around lighter weeks 8 and 12. Long runs of 4 h 55 to 5 h 20, back-to-backs of about two hours.
• Peak, weeks 13 to 17. About 11 hours. Five-and-a-half-hour long runs, race rehearsals among them, and climbing of 3,000 m a week, the race's own total.
• Taper, weeks 18 to 20. About 9, then 7 hours, then race week.

Who this plan is for

Ultra levels come from experience, because trail finish times depend on the course. Experienced means at least one ultra finished and 6 to 8 hours a week of running now. The plan starts at about 6.9 hours. Every session is minutes at an effort, with heart-rate ranges if you add your max heart rate.

Back-to-backs, honestly

A back-to-back is a second long-ish run the day after the long run. In this plan it is easy, about a fifth of the week, and followed by a rest day. It shows up from the build phase on.

The idea is simple. The second half of a 100k is run on legs that are already tired. A back-to-back lets you practise that without doing one six- or seven-hour training run.

What the research says about it: nothing directly. We found no published trial comparing back-to-back weekends with single long runs. It is common coaching practice, and this plan labels it that way. What the research does support is the backbone around it. In 100 km runners, weekly volume was one of the strongest training predictors of race time (Knechtle et al. 2010), and ultra runners rely on volume more than marathoners (Rüst et al. 2012). Back-to-backs are one way to fit that volume into a working week.

So the plan keeps them conservative:

• Easy effort only. No steady finish, no hills on purpose.
• Capped at about a fifth of the week, up to two hours at the peak.
• A rest day after, every week.
• Replaced by a short easy run in base weeks, recovery weeks and the taper.

90 % of the running is easy.

Your own plan

The 100k and 50 mile ultra training plan generator builds yours from your race date, running days, long-run day, experience and the race's total climb. Runs of two hours or more carry the ISSN fuelling target: 30 to 50 g carbohydrate and 450 to 750 mL fluid per hour. Free, no email, PDF included.

FAQ

Can I swap the long run and the back-to-back? Yes. Some runners prefer the shorter run first. Keep the rest day after the pair.

How long should the longest run be for a 100k? 5.5 hours in this plan, repeated through the peak, with a back-to-back the day after.

What if the back-to-back feels awful? It is meant to feel heavy, not painful. Slow down, hike more, and cut it short if your form breaks down.

Does the plan work for a 50 miler with more climbing? Yes. Enter the race's total climb and the weekly climbing targets follow it.

Plan your race fuelling:

More in this series: the first-ultra and competitive 100k / 50 mile plans and the experienced 50k plan.

Sources

• Knechtle et al. 2010, predictors of 100 km race time
• Rüst et al. 2012, training of 100 km ultra-marathoners and marathoners
• Tiller et al. 2019, ISSN position stand on ultra-marathon nutrition

Cover image: TrainingZones.