Experienced 100k or 50 Mile Ultra Training Plan: 20 Weeks
A 20-week 100k or 50 mile trail plan for runners with an ultra behind them: peak 11 hours, 5.5-hour long runs, back-to-backs up to 2 hours. Free.
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.
| 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 |
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:
Target carbs
60g/h
Per hour of exercise
Total carbs
120g
Across your 2-hour session
Recommended carbohydrate by session length
| Under 1 hourWater is usually enough | 0 g/h |
| 1 to 2.5 hoursRecommendedSingle transportable carb (glucose) | 60 g/h |
| 2.5 hours or longerGlucose plus fructose, near a 2:1 mix | 90 g/h |
- Pair carbohydrate with fluid and sodium. Concentrated fuel without enough water sits in the gut and causes discomfort.
- Tolerating high carbohydrate rates is a trainable skill. Practice your race fueling in long sessions and build up gradually, never try a new high intake on race day.
- Above 60 g per hour, use a glucose-to-fructose mix near 2:1. Glucose alone saturates the gut transporter at about 60 g per hour.
- Hard efforts burn carbohydrate faster, so sit toward the top of each range.
A PDF of your personalized results, with a QR code to reopen them anytime.
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.