First 100k or 50 Mile Ultra Training Plan: 20 Weeks on Trail
A 20-week plan for your first 100k or 50 mile trail ultra: peak 9.5 hours, 4.5-hour long runs, back-to-backs, climbing and a fuelling plan you train. Free.
A first 100k or 50 mile trail plan runs 20 weeks at five runs a week, peaks at about 9.5 hours, and builds long runs to 4.5 hours with a back-to-back of up to 110 minutes the next day. It fits runners who have finished a 50k or a marathon on trail and train 4 to 6 hours a week. It is written in time and effort, not pace, and it trains your fuelling as much as your legs.
The 20 weeks
Sample plan · 100k / 50 mile trail ultra, first ultra
20 weeks, 5 runs a week, peak week 9h 25m, longest run 4h 30m, up to 2400 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 | 5h 45m · 850 m | Easy running only | 2h 10m long run |
| 2 Base | 5h 59m · 900 m | Easy running only | 2h 20m long run with power hiking |
| 3 Base | 6h 12m · 1250 m | Hill repeats: 4 × 3 min I (3 min jog) | 2h 25m long run |
| 4 Base, recovery | 5h 09m · 850 m | Long hill intervals: 3 × 6 min T (4 min jog) | 1h 55m long run with power hiking |
| 5 Base | 6h 59m · 1400 m | Power-hike repeats: 3 × 8 min power hike (4 min jog) | 2h 40m long run |
| 6 Base | 7h 11m · 1500 m | Hill fartlek: 7 × 90 s I (90 s jog) | 2h 50m long run with power hiking |
| 7 Base | 7h 44m · 1550 m | Hill repeats: 4 × 3 min I (3 min jog) | 2h 55m long run |
| 8 Build, recovery | 5h 58m · 950 m | Long hill intervals: 3 × 6 min T (4 min jog) | 2h 55m long run with power hiking |
| 9 Build | 8h 08m · 2150 m | Power-hike repeats: 3 × 8 min power hike (4 min jog) | 4h long run, steady finish |
| 10 Build | 8h 36m · 2200 m | Hill fartlek: 8 × 90 s I (90 s jog) | 4h 10m long run with power hiking |
| 11 Build | 8h 49m · 2300 m | Hill repeats: 5 × 3 min I (3 min jog) | 4h 20m long run, steady finish |
| 12 Build, recovery | 6h 52m · 1100 m | Long hill intervals: 3 × 6 min T (4 min jog) | 3h 25m long run with power hiking |
| 13 Peak | 9h 25m · 2400 m | Power-hike repeats: 3 × 8 min power hike (4 min jog) | 4h 30m race rehearsal |
| 14 Peak | 9h 16m · 2400 m | Hill fartlek: 10 × 90 s I (90 s jog) | 4h 30m long run, steady finish |
| 15 Peak | 9h 04m · 2400 m | Hill repeats: 6 × 3 min I (3 min jog) | 4h 30m race rehearsal |
| 16 Peak, recovery | 7h 04m · 1100 m | Long hill intervals: 3 × 6 min T (4 min jog) | 3h 25m long run, steady finish |
| 17 Peak | 9h 19m · 2400 m | Power-hike repeats: 3 × 8 min power hike (4 min jog) | 4h 30m longest run: race rehearsal |
| 18 Taper | 7h 13m · 1500 m | Hill fartlek: 6 × 90 s I (90 s jog) | 3h 35m long run |
| 19 Taper | 5h 44m · 1150 m | Hill repeats: 4 × 3 min I (3 min jog) | 2h 40m 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. 5.8 to 7.7 hours. Long runs from 2 h 10 to 2 h 55, every second one with power hiking. The hill session starts in week 3 and rotates through hill repeats, long hill intervals, power-hike repeats and hill fartlek.
- Build, weeks 8 to 12. 8.1 to 8.8 hours around lighter weeks 8 and 12. Long runs of 4 to 4 h 20, back-to-backs of 95 to 110 minutes.
- Peak, weeks 13 to 17. 9.1 to 9.4 hours. Race rehearsals of 4.5 hours in race kit, climbing up to 2,400 m a week. Week 17 holds the longest run.
- Taper, weeks 18 to 20. About 7.2, then 5.7 hours, then race week.
Who this plan is for
Ultra levels come from experience, because trail finish times depend on the course. First ultra means your first 100k or 50 miler, with a 50k or a trail marathon behind you and 4 to 6 hours a week of running now. The plan starts at about 5.8 hours. If that is a jump from where you are, pick 24 weeks: the extra weeks go into base.
Fuelling decides the finish
At 100 km, eating and drinking become part of the training. Legs trained for four and a half hours still need fuel for every hour of the race.
The International Society of Sports Nutrition position stand on ultra-marathons (Tiller et al. 2019) gives the targets for racing:
- 150 to 400 kcal an hour, with 30 to 50 g carbohydrate and 5 to 10 g protein, from a variety of calorie-dense foods.
- 450 to 750 mL fluid an hour, about 150 to 250 mL every 20 minutes.
- Sodium above about 575 mg per litre, more than most sports drinks provide, especially in heat.
- Savoury food as the race gets longer, because preference shifts toward it.
The same paper recommends training the gut. So every run of two hours or more in this plan carries the fuelling target, and the peak race rehearsals are where you test the exact food, drink and timing you will use on race day. By week 17 you should have eaten your race food on at least five runs of four hours or more.
The rest of the plan keeps you healthy enough to get there: 90 % easy running, weekly time rising at most 10 % between loading weeks, and a three-week taper.
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. Every session shows time, effort, climbing and purpose. Free, no account, PDF included.
FAQ
Is the plan the same for 100k and 50 miles? Yes. 50 miles is 80 km, close enough to 100 km that the training is the same: long days on your feet, back-to-backs, climbing and fuelling. Enter your race's climbing.
How long should my longest run be before a first 100k? 4.5 hours in this plan, several times in the peak, each followed by a back-to-back. The race adds the rest, on tapered legs.
Should I eat real food or gels? Both, as the ISSN recommends a variety of calorie-dense foods. Practise whatever the race provides at its aid stations.
What if I can only train four days a week? The plan keeps the long run, the back-to-back, the hill session and one easy run, so more of the week sits on the weekend.
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 experienced and competitive 100k / 50 mile plans and the first 50k plan.
Sources
Cover image: TrainingZones.