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Jason Kelly  •  Running Training •  12.02.2021 •  9 min read

Ultra marathon training: Transitioning from marathons to ultras

So you’ve completed a marathon or two and are now looking for a fresh challenge? Or maybe you’re a seasoned distance runner thinking about the next way to test your limits? Why not have a crack at an ultra marathon?

As intimidating as it may sound, ultra marathon training doesn’t necessarily have to be too much different from traditional marathon training.

An ultra marathon is defined as any race which is longer in distance than a marathon (26.2 miles/42.2km). The most common distances for an ultra are 50km, 50 miles, 100km and 100 miles. There are plenty of ultras which are in between these distances or much longer still! Ultras are a brilliant test of both your physical and mental strength. The highs and lows that you go through in a race will stay with you for long after it is over.

It’s usually a good idea to start off with one of the shorter ultra distances if you are new to the discipline, rather than diving straight into a 100+ miler! Setting an effective and realistic goal will be your first step, whether it’s simply to finish or to be competitive.

Key differences from marathon training

Unlike marathons, ultra marathons are not one single defined distance. There is therefore a huge amount of variety between them and this is probably the biggest factor to consider when thinking about a training plan. This is the principle of specificity.

It is important to train on terrain and elevation similar to the race you are targeting when possible. Training for a track 100 mile race by only running in the hills or training for a mountain 100km by doing loops of your local parkrun route is not going to give you the best chance of success!

Jason running in dark with headtorch
Nocturnal Ultra 2019

If your target race is a hilly trail ultra then think about adding a midweek trail run with some hill sprints at the end into your plan or if your target race is a flat 50km then think about adding in a weekly tempo effort on an old railway line/canal path etc. to help condition your body for the specificities of the race.

The 'long run' in ultra marathon training

The weekly long run is vital in preparing you physically and mentally for the challenge ahead. If you’re going to be out for multiple hours on race day then you need to have had the experience of being out for a few hours at a time in training to learn how your body will respond.

How long should they be?

The maximum distance of the long run in ultra training is an often debated topic because the longer you go, the higher your risk of injury. Camille Herron, the female world record holder for 50 miles, 100 miles, 12 hours and 24 hours, never runs more than 20 miles at a time in her training blocks whereas some hardy athletes such as Kilian Jornet like to run up to 50 mile training runs in preparation for 100 mile races.

Shot through the grass of Jason running
Glen Doll

The best answer for most people likely lies somewhere in between, with a maximum long run distance of between 20 and 35 miles (~30-60km) generally favoured, depending on the terrain and target race. If the target race is a particularly long ultra, many people find some benefit in doing back-to-back long runs. This could be something like 20 miles (32km) each day on consecutive days and will get your legs used to running long while fatigued but without the higher risk of a single much longer run.

Time on feet

It’s important to note that the distance may not always be the most important factor for your long run. If your target race has a significant amount of elevation gain then it can be a good idea to try and prioritise elevation gain rather than distance in the long run. For example, trying to get as much vertical climb as possible in a 3 hour run could be of much more benefit than going for a flat 3 hour run if it replicates the terrain of your target race more closely, even though you will not cover as much distance and may be walking/hiking at times. In such circumstances, using ‘time on feet’ as the guide for the long run can be of more benefit than thinking only about distance.

Allow for recovery

Remember that everybody takes different amounts of time to recover. So if you feel like your legs are still tired for the next week after a long run, or you are really struggling to hit a target distance, there is no shame in cutting the distance or intensity down a bit. Getting to the start line healthy is always the primary goal here! Your long run should be long enough to challenge your body but short enough that you don’t compromise the rest of your training week.

Progression of the 'long run'

As with marathon training, you shouldn’t dive straight into your maximum distance right at the start of the training plan. The long run distance/duration should be built up over the period of the training block. Starting from what you are comfortable with at the moment, building up to your longest training run around 3 or 4 weeks prior to race day. Ideally not adding too much more than 10% to the distance or time each week to avoid over-stressing the body.

Two men running through the snow
Mount Battock


Many marathon training plans call for sections of the long runs to be run at a faster ‘target race pace’. This can be very useful when training for the marathon distance. However, given that ultras are longer (sometimes substantially longer!) than marathons, your ‘race pace’ is more likely to be closer to, or even much slower than, your normal ‘easy pace’. This means that ‘race pace’ sections in long runs are not as common in ultra marathon training plans. Generally the long runs are all run at an easy pace. This doesn’t mean that you can’t pick up the pace in a long run if you are feeling good, but try to just go by feel rather than aiming for a specific pace. Make sure not to overdo it!

Nutrition in ultra marathon training

Another key component of ultra marathon training which ties into the long run is nutrition. Whether you are training for a 50km or 100+ miles, you are going to need to be eating and drinking little and often during the race to keep the energy levels up. This can get quite difficult when you are at the business end of a tough long race so you need to practise this as much as possible in training.

The body can react in quite unpleasant ways if your stomach takes a turn after trying a new kind of fuel for the first time!

Jason running Speyside Way Ultra
Speyside Way Ultra 2020

Always try out the foods and drinks that you plan to use in the race when you are doing your long training runs and work out what works for you and what doesn’t. You may still be in for some surprises on race day but at least you will be as prepared as you can be.

As a side note: this goes for all of your kit and shoes as well! Make sure that everything has been tried out in training!

Speedwork in ultra marathon training

Do I still need to work on my speed for an ultra marathon?

Speedwork is still very much an important part of training for an ultra marathon. You may think that your pace during the event will be slower than the likes of a 10km or half marathon so there is no need to do any fast running in training but you’d be wrong!

Interval training and tempo runs not only improve your top end speed but they can also drastically improve your aerobic capacity and running economy; that is the maximum amount of oxygen the body can utilise during activity and the volume of oxygen required to sustain a given pace. If you are using less oxygen when running at an easy pace then you will be able to sustain it for much longer before slowing down. Check out the Tempo vs Interval Training section in this article for a much more detailed explanation of the benefits of speedwork for all distances.

The 80:20 principle

Most research suggests that the optimal ratio for easy to hard running in training is around 80:20. This means that around 20% of your weekly mileage should be done at a high intensity (anaerobic) and the other 80% should be done at a low intensity (aerobic). A good rule of thumb is that easy runs should be at a pace which you can comfortably hold a conversation at. The high intensity running is usually best split into 1 or 2 hard interval/tempo sessions per week, always having at least a day or two of easy running in between to allow the body to recover and reap the benefits of the session.

The taper in ultra marathon training

As you approach the last few weeks of the training block, the main goal switches from building fitness and endurance to allowing the body a bit of time to recover in order to leave you feeling fresh on race day – the ‘taper’.

Reduce your weekly mileage

A typical taper would start after your last long training run, usually around 3 weeks before race day, and would be a gradual reduction in training volume as the event approaches. Reducing your total weekly mileage by around 20% each week in these last few weeks should help to get some life back into the legs and ensure that you are feeling strong and not burnt out.

Lower the intensity

You can still keep the higher intensity sessions but it is usually a good idea to reduce the number of reps in an interval session or reduce the time of a tempo session in the taper phase. The last speed session could be 5-7 days before the race provided it is kept relatively low-volume and then you can just enjoy some very easy paced runs and a day or two off if you feel like you need it before being all set to smash it on race day!

Enjoy the process!

Running an ultra can be a very rewarding experience and training for an ultra comes with so many huge physical and mental benefits so it really is something that is worth having a go at. As always, the most important thing is to enjoy the process!

Jason running El Calafat
El Calafat
Ultras are a brilliant test of both your physical and mental strength. The highs and lows that you go through in a race will stay with you for long after it is over.

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