It's one of the most iconic ultramarathon distances. 100K is just a shade over 60 miles - that's two back-to-back marathons, and then some!
If you're considering running a 100K, it's a smart idea to follow a structured training plan to prepare yourself for the demands of the race. So, we've teamed up with international athlete and UKA certified coach, Sarah McCormack, to give you the ultimate 100K training plan.
This plan is not for beginners. It's aimed at experienced runners who are targeting a hilly, trail 100K ultramarathon event. Use Sarah's plan if you:
- Are used to running two harder runs per week
- Have a regular minimum mileage of 70-80K per week
- Have completed at least two ultramarathon races previously
We hope you “enjoy” the plan, and would love to hear how you get on. Happy running!
BEFORE YOU START
It's important to be honest with yourself before embarking on a training plan. Sudden jumps in weekly mileage, ascent and speedwork are a recipe for injury or burnout.
Our 100K trail ultramarathon plan is for experienced runners. You will need to already be running a high mileage in training - at least 70K per week, and also have completed a couple of ultras previously.
If you don't tick those boxes, it's worth looking at our 50-mile training plans. Here we offer two options, one for runners who have never completed an ultra before, and another for people looking to improve.
SARAH MCCORMACK'S 100K TRAIL ULTRAMARATHON TRAINING PROGRAM
It's important you read the training guidelines in conjunction with this program, as it explains the sessions in more depth. It's also worth reading the section on working out your effort levels too, particularly where the plan talks about running sessions at different race paces.
Download the 100K training plan as a PDF
| Week | Mon | Tues | Weds | Thurs | Fri | Sat | Sun |
1 | Rest | Hill reps: 5 x 2.5 minutes hard uphill with easy jog recovery back to your starting point. Aim for fastest sustainable pace & consistent pacing between reps | 10K - easy run on hilly trail | 8K - easy, with 6 x 20s strides. This run should be done on the flat | Tempo run: 25 min steady @ 3h race pace (65% effort) | 10K - easy run on hilly trail | 25K long run with 25% of the climb you will do in your race |
| 2 | Rest | Hill reps: 5 x 3 minutes hard uphill with easy jog recovery back to your starting point. Aim for fastest sustainable pace & consistent pacing between reps | 10K - easy run on hilly trail | 8K - easy. This run should be done on the flat | Tempo run: 30 min steady @ 3h race pace (60% effort) | 12K - easy run on hilly trail | 20K long run with 15% of the climb you will do in your race. In the last 20 mins of this run, include 10 minutes running at 2h race pace (a moderately hard 80 % effort) |
| 3 | Rest | Fartlek: 6 x 3 minutes hard, with 90s easy jog recovery between efforts | 10K - easy run on hilly trail | 8K - easy. This run should be done on the flat | Progression run: 20 mins @ 3h race pace (65% effort), followed immediately by 10 mins @ 2h race pace (80% effort) | 8K - easy run on hilly trail | 30K long run with 30% of the climb you will do in your race |
| 4 | Rest | Hill reps: 5 x 4 minutes hard uphill with easy jog recovery back to your starting point. Aim for fastest sustainable pace & consistent pacing between reps | 10K - easy run on hilly trail | 8K - easy, with 6 x 20s strides. This run should be done on the flat | *2 x 20 min steady @ 3h race pace (60% effort), with 5 minutes easy running in between | 12K - easy run on hilly trail | 20K long run with 20% of the climb you will do in your race |
| 5 | Rest | Fartlek: 6 x 4 minutes hard, with 2 minutes easy jog recovery between efforts | 10K - easy run on hilly trail | 8K - easy. This run should be done on the flat | Alternation run: 5 x 1 min @ 1h race pace (90% effort)/5 min @ 3h race pace (65% effort) | 8K - easy run on hilly trail | 35K long run with 40% of the climb you will do in your race |
| 6 | Rest | Hill fartlek: 30 min session in which you run hard on all climbs and easy on all flats and descents | 10K - easy run on hilly trail | 10K - easy. This run should be done on the flat | 8K - easy, with 6 x 20s strides | 12K - easy run on hilly trail | *20K long run with 15% of the climb you will do in your race. In this run incorporate 45 mins @ 3h race pace (65% effort) |
| 7 | Rest | 10K - easy | Fartlek: 8-6-6-4 minutes hard, with 2 minutes easy jog recovery between efforts | 8K - easy. This run should be done on the flat | 6K - easy | *Progression run: 20 mins @ 3h race pace (65% effort), followed immediately by 20 mins @ 2h race pace (80% effort) | 40K long run with 40% of the climb you will do in your race |
| 8 | Rest | Hill fartlek: 40 min session in which you run hard on all climbs and easy on all flats and descents | 10K - easy run on hilly trail | 8K - easy. This run should be done on the flat | 10K - easy, with 6 x 20s strides | 8K - easy run on hilly trail | *20K long run with 15% of the climb you will do in your race. In this run incorporate 60 mins @ 3h race pace (65% effort) |
| 9 | Rest | 10K - easy | Fartlek: 4 x 7.5 minutes hard, with 2.5 minutes easy jog recovery between efforts | 8K - easy. This run should be done on the flat | 6K - easy | *Progression run: 20 mins @ 3h race pace (65% effort), followed immediately by 15 mins @ 2h race pace (80% effort), then 5 mins @ 1h race pace (90% effort) | 45K long run or trail marathon race with 50% of the climb you will do in your race |
| 10 | Rest | Hill fartlek: 40 minutes session. Run hard on all climbs (1h race pace, or 90% effort). On all flats and descents run at 3-4h race pace | 10K - easy run on hilly trail | 10K - easy. This run should be done on the flat | 10K - easy, with 6 x 20s strides | 12K - easy run on hilly trail | *25K long run with 25% of the climb you will do in your race. In this run incorporate 75 mins @ 4h race pace |
| 11 | Rest | 10K - easy | Hill reps: 4 x 2 minutes hard uphill with easy jog recovery back to your starting point. Then follow with 25 minute tempo @ 2h race pace (80-85% effort) | 8K - easy. This run should be done on the flat | 8K - easy | 5K - easy run on hilly trail | 50K long run with 50% of the climb you will do in your race |
| 12 | Rest | 8K - easy | 10K - easy run on hilly trail | 14K - easy. This run should be done on the flat | 10K - easy, with 6 x 20s strides | 8K - easy run on hilly trail | *30K long run with 25% of the climb you will do in your race. In this run incorporate 90 mins @ 4h race pace |
| 13 | Rest | 10K - easy | Fartlek: 3 x 8 minutes hard, with 3 minutes easy jog recovery between efforts | 8K - easy. This run should be done on the flat | 6K - easy | Alternation run: 3 x 5 mins @ 1h race pace (90% effort)/15 min steady @ 4h race pace | 45K long run with 35% of the climb you will do in your race |
| 14 | Rest | 8K - easy | 8K - easy run on hilly trail | Hill fartlek: 40 minutes session. Run hard on all climbs (1h race pace, or 90% effort). On all flats and descents run at 3-4h race pace | 10K - easy | 12K - easy run on hilly trail | *25K long run with 25% of the climb you will do in your race. In this run incorporate 60 mins @ 4h race pace |
| 15 | Rest | 8K - easy | Progression run: 40 mins @ 4h race pace, followed immediately by 10 mins @ 2h race pace (80% effort) | 8K - easy. This run should be done on the flat | 6K - easy | Tempo run: 30 min steady @ 3h race pace (60% effort) | 15K long run with 10% of the climb you will do in your race |
| 16 | Rest | 8K - easy. In the last 20 minutes of this run, include 10 minutes running at 3h race pace (65-70% effort) | 8K - easy run on hilly trail | 6K - easy, with relaxed 4 x 20s strides. This run should be done on the flat | Rest | 3K - easy run on hilly trail | Race |
*Runs marked in bold are good opportunities to test your race day fuelling strategy.
ABOUT SARAH
Sarah McCormack is an athlete, running coach and INOV8 ambassador. Based in Cumbria, Sarah is an accomplished trail, cross country and mountain runner. Her victories include:
- Irish Cross-Country Champion (2014)
- 3x winner of the Snowdon International Mountain Race (2014, 2015 and 2019)
- Mountain Running World Cup Winner (2019).
Sarah uses her wide-ranging running experience to coach and develop other athletes, designing individual training plans to help them achieve their goals. Visit her website, Missing Link Coaching, for more information.
TRAINING PLAN GUIDELINES
For structured sessions, warm up for 10-15 minutes before (including 4 x 10s strides) and warm down for 10-15 minutes after. Structured sessions are tempo runs, fartleks, hill reps, progression runs, and runs with surges.
Fartleks
Aim for a hard 90% effort for your reps - but not flat out (90% effort is approximately your one-hour race pace). Your fartleks can be done on firm, rolling trail, or on grass in a park.
Surges and strides
These are not sprints! They are fast 10-30 second accelerations that are great in a warm-up for a session/race, or as a way of including a little bit of leg speed training at the end of your easy run. They should be nice and quick, but not flat-out sprints. Aim around 80-90 % of your top speed, so you get the benefits of spinning the legs quickly without any fatigue or muscle soreness.
Tempo runs
Most of these should be done at a steady 65-75% effort, which is approximately three-hour race pace.
Hill reps
You should run these reps at your fastest sustainable pace (but aim for consistent pacing).
If you only have a small hill to work with, it's fine to improvise. You could:
- Run back down again when you reach the top, then go up again, until you accumulate the total amount of uphill running time.
- Start with a flat run into your hill. For instance, if the plan specifies a 4-min uphill rep, but you only have a 2-min hill, you'd run 2 mins hard on the flat then straight into 2 mins hard uphill.
- Use a treadmill with an incline function.
When running hills, you should aim to work on your technique too. Our blog “10 Essential Tips For Running Up And Down Hills” is packed with useful information to help you make short work of challenging climbs and technical descents.
Training terrain
Training on terrain that mimics the route you'll be racing on can really help, particularly for your easy and long runs. However, don't make big changes to the amount of weekly elevation that you're accumulating.
Long runs
Ultramarathons can be quite hilly. The long runs in the training plan are designed to prepare you for this come race day. Each long run has a percentage of the race-day climb that you should aim to do. For example, if your race has 1,000 metres of ascent, and your long run says you need to run 30% of that climb, you should incorporate 300 metres of climb into your route.
Run your long runs at an easy pace, unless otherwise stated in the plan.
WORKING OUT YOUR EFFORT LEVELS
Understanding your effort level is a key skill in being able to pace and execute a successful ultramarathon. Gauging your effort levels during your fartlek, tempo and progression runs will help you get a really good sense of pacing... even if it takes a little bit of trial and error!
1-hour race pace
- Feels like a controlled hard effort, but not working quite at your limit. The pace will feel difficult to sustain and you'll be looking forward to the rep being over!
- You should only be able to say a few words at a time.
- Maintaining this pace will feel like you are working at 90 % effort, closer to 95 % towards the end of the session.
1.5-hour race pace
- This is a controlled hard effort, and slightly below your lactate threshold pace, so it should feel slightly more sustainable than 1h race pace.
- You'll probably be able to say a full sentence, with a few pauses for hard breathing between words.
- This pace might feel like 80 % effort right at the start of the session, but it will quickly progress to feeling more like 85-90 % effort.
2-hour race pace
- Feels like a moderately hard effort, but that you're keeping something in reserve.
- You might be able to say 1-2 sentences at a time, but will have to pause between words frequently to breathe.
- Maintaining this pace will feel like you are working at 80 % effort, closer to 85 % by the end of the session.
3-hour race pace
- Feels like a fairly fun, cruising effort… at least for durations of 20 mins or less!
- You should feel like you're keeping plenty in reserve and able to say multiple sentences without too much difficulty.
- After the first 15-20 mins of running at this pace, an element of fatigue will start to creep in. However, this should be a gradual process, and your main feeling should be one of moving economically and with only moderate effort.
- Finish these tempo runs with plenty left in the tank.
- Maintaining this pace will feel like you are working at 65-70 % effort, closer to 75 % by the end of the session.
4-hour race pace
- Not too different from 3-hour race pace - on the flat 4-hour pace might be 10 seconds per mile slower.
- It should feel like a relaxed cruise, especially in the initial stages of the session. You may even feel you need to hold yourself back a bit, in order not to exceed the desired intensity.
- You should be able to speak in full sentences and take in your surroundings.
- After the initial 20-30 minutes, you'll start to notice an element of fatigue begin to build. However, this effort level should mainly feel like a moderate, enjoyable, sustainable intensity.
- After about an hour of maintaining this pace, the feeling of mounting fatigue will become more noticeable, although you should still feel strong and in control throughout.
Easy runs
- By contrast, easy runs should be very relaxed and within your comfort zone.
- You should be able to have a full conversation and not need to pause for breath in the middle of a sentence.
- If you're running in hilly terrain, it may be necessary to incorporate some hiking on the steep sections, to ensure that your effort level doesn't shoot up.
- In general, easy runs should feel like 30-40 % effort.
FUELLING DURING SESSIONS & RACES
It's important to practice fuelling during your more ultra-specific training runs. This will help you to work out a fuelling strategy for race day and train your gut to absorb nutrition while you're moving. In general, 60g carbohydrate/hour is a good minimum intake rate to aim for, though fuelling requirements vary on an individual basis and may take a bit of trial and error.
In the training plan, the runs marked in bold font offer a good opportunity to test out your race-day fuelling strategy.
Where this run is only an hour long (including warm up and warm down), this might be as simple as bringing a couple of gels and a drink. For Sunday long runs, this may require bringing a number of snacks such as gels, chews, or carbohydrate mixed into your drink, in order to achieve at least 60g carb/hour for the full duration of your run.
It's also a good idea to test out your pre-race breakfast before the long runs that include faster running. For Sunday long runs where full race-day fuelling is not suggested, it's still a good idea to bring a drink and some snacks.
If you're looking for some further inspiration, check out our blog “Top 10 Trail Running Superfoods”.
PREPARATION RACES
It can be useful to include at least one preparation race in the build-up to your 100k. Preparation races are useful opportunities to test out your race-day routine, shoes, kit, pacing, fuelling, etc., before the main event.
You can swap a race for a weekend long run. In the plan we suggest that a trail marathon on week nine of would be ideal. If you decide to do this, be sure to drop the Friday hard run that week, and take a rest day (or very short, easy run day) before your race instead. It would also be a good idea to skip the hard sessions from the following week, to give yourself ample recovery.
STRENGTHEN YOUR BODY AND MIND
You've raced ultras before, so you know that running alone isn't the only training you need to do.
Ultras are as much about your brain as they are your body. Check out record-breaking ultra-runner Damian Hall's mental tips for ultramarathons. It's well worth a read - particularly if you're going through a tough period in training, or you're approaching race day.
We all know that strength and conditioning is an important part of arriving at the start line healthy. But this is often the thing that gets pushed out during a challenging training cycle. If you've got time for nothing else, why not try this twice-weekly, trail specific strength workout? Your legs will thank you later!
SOME GREAT 100K ULTRAS TO TRY
If you're in need of inspiration for your next race, check out our top picks of ultramarathons that are around 100K long:
- Lakeland Trails Ultra (100K), Lake District
The Lakeland Trails 100K Ultra takes in no less than 5 mountain passes, during a course with nearly 3,800 metres of ascent. The race starts at midnight, so make sure your headtorch is fully charged! - Cheviot Goat Winter Ultra Run, Northumberland
At 55 miles, this one's a bit shorter than 100K, but that doesn't mean it's easier! Run at the beginning of December, the Cheviot Goat takes in 3,700 metres of climb as you battle the inhospitable landscape and conditions. - Race To The King, West Sussex
A challenging ultramarathon for seasoned runners and newbies alike. The course takes in 1,600 metres of ascent in a figure of eight loop the starts and ends at Goodwood Racecourse.