100K is a long day, so the plan practises the day
100K is about 62 miles. It is longer than a 50-mile race, and many editions will still have you moving after dark. This 20-week plan is for runners who have finished a 50-mile or 100K-length day before, or who already run a comfortable long run of about 4 hours, on trails, with food. If your longest recent run is closer to 2 hours, start with the 50K plan. A 100K title will not supply the missing months.
Awaiting publisher review. This is a general schedule from Running for Good Ultra, not a personal programme and not an independent coaching or medical review. The NHS says to speak to a GP if you have a medical condition or you have not exercised for some time. Nothing in this table replaces that.
Walking, eating and a set of lights belong in the weeks
From week 6, decide the walks before you start the long run. A steady walk on the climbs is part of the session. So is eating a small amount on a schedule you can remember when you are tired, about every 30 to 40 minutes, using foods you have already tried. This is a rehearsal habit, not a prescription of how many grams you need. For that, use the fuelling guide and, if you need a personal plan, a registered sports dietitian.
Week 14 starts in the late afternoon so the last part needs your race lights. Walk and eat in that section too. If the route you choose for training is not safe in the dark, move the session to a route that is, or delay it. Do not add an unlit section to make the plan look complete.
Ordinary weeks have three easy runs of about 50, 60 and 70 minutes, one of them with 6 short hills when the table says so. Back-to-back weeks have two easy weekday runs, about 50 and 60 minutes. Easy means you can talk.
The 20 weeks
Put the race on week 20. The longest single run is 5 hours 30, on tired legs the next morning for another 2 hours 30. You do not cover 100K in training. Race day is the first time you do.
| Week | Weekend | During the week |
|---|---|---|
| 1 | 3 hours 15 | Three easy runs |
| 2 | 3 hours 30 | Three easy runs |
| 3 | 3 hours 45 | Three runs, one with hills |
| 4 | 2 hours 30 | Three shorter easy runs. Easier week. |
| 5 | 4 hours | Three easy runs |
| 6 | 4 hours 15, with planned walks | Three easy runs |
| 7 | Saturday 4 hours, Sunday 90 minutes easy | Two easy runs |
| 8 | 2 hours 45 | Three shorter easy runs. Easier week. |
| 9 | 4 hours 30 | Three easy runs |
| 10 | 4 hours 45 | Three runs, one with hills |
| 11 | Saturday 4 hours 30, Sunday 2 hours easy | Two easy runs |
| 12 | 3 hours | Three shorter easy runs. Easier week. |
| 13 | 5 hours, with walks and regular food | Three easy runs |
| 14 | 4 hours 30, starting late afternoon | Three easy runs. Check the lights before you leave. |
| 15 | Saturday 5 hours 30, Sunday 2 hours 30 easy | Two easy runs. Peak weekend. |
| 16 | 3 hours | Three shorter easy runs. Easier week. |
| 17 | 4 hours | Three easy runs |
| 18 | 2 hours 30 | Three easy runs, about 40, 45 and 50 minutes |
| 19 | 90 minutes | Two or three easy runs of 30 to 40 minutes |
| 20 | Race | Two or three easy runs of 20 to 30 minutes early in the week |
A missed peak is not replaced in race week
Repeat a missed long-run week once. If you miss the peak weekend, do not move it into week 18 or 19. Arrive underdone rather than exhausted. Two lost weekends means the race date is the thing to change.
Stop and get medical care for chest pain, dizziness, fainting, or pain that changes how you move. Check the race cutoff separately. A 100K limit might be a day and a night, or it might be tighter. The plan does not know which you entered.
Sources & further reading
Awaiting publisher review. This is a general schedule from Running for Good Ultra, not a personal programme and not an independent coaching or medical review. The dusk run is a rehearsal of lights and food, not a requirement to race through the night in training.
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