Trail Runner to Road Marathon: How to tweak your training to nail a road marathon

Last updated: 02-Oct-18

By James Eacott

Marathon runners are a strange breed. Coming from us ultra runners, that’s saying something. But they are. They pound tarmac for miles, run right on the edge of their lactate threshold and in urban jungles. And their shorts are really, really short.

It’s a transition most runners make in the opposite direction. Road marathon runners tend to transition to trail running either, when they’ve reached their speedy PB, or their joints are starting to complain, and the soft trails beckon.

Whatever the reason, few transition the other way.

It surprises me how many of us dive straight into ultras (myself included) without completing a marathon first. But for most of us, it just never appealed. Pounding tarmac for mile upon mile, chasing splits and spending too long staring at my Garmin rather than the scenery. No thanks. Plus, anyone can run a marathon, right? So where’s the challenge?

However, having now completed many ultras I find myself pondering what I could do over the marathon distance. This got me wondering: what tweaks would I need to make to transition from ultra runner to road marathon runner (for a couple of months, anyway).

Training Tweaks

Ultra running has given us a fantastic starting point for our marathon training. Why? Because we’re strong diesel engines. We are great at pacing ourselves and endurance certainly isn’t going to be a problem. Neither is strength. Our joints and ligaments are well capable of running 26.2 miles (on trails, at least).

The flip side of this, however, is that most of us are great, big slow-twitchers. By that I mean all our fast-twitch fibres have been somewhat suppressed in our pursuit for endurance. But fear not, they are still there. They just need to be activated!

The Need for Speed

We often neglect speedwork as ultra runners because, well, quite frankly we don’t think there’s much need for it when we race at such slow speeds. I believe we need speedwork even for ultra training, but it certainly cannot be neglected when working towards a marathon, particularly coming from an ultra background.

Speedwork drastically improves cadence (turnover) and running economy. Performing a speed session once every 7-10 days will reap big rewards. There are sample speedwork sessions in this article.

All Things Tempo (aka Threshold)

There’s no avoiding it: running a marathon hard (whatever ‘hard’ looks like to you) makes for a very uncomfortable few hours. That’s because you run it at a pace relatively near your lactate threshold. If your lactate threshold (roughly defined as the pace you can hold for approximately 60 minutes) is 08:00mm (minute mile), then you might be looking to run a marathon at something near 08:45mm…surprisingly close to that rather grim pace.

To increase the ceiling of your lactate threshold, you need to embrace the weekly tempo or threshold run. Tempo pieces should be run somewhere between your 10km and half marathon pace. Running at this pace will improve your lactate threshold, which means that your marathon pace will also be elevated over time.

Start by introducing short tempo pieces into an easy run. For example, after a 10-minute warm up, do 3 x 8-minute tempo pieces with 5 minutes’ easy jog between each. You can gradually increase this to 4 x 10 minutes, 3 x 20 minutes and 2 x 30 minutes as your fitness improves.

Marathon Paced Madness

We’re used to our Long Slow Runs being rather long and slow…as they should be! For marathon training, you’ll want to reduce the ‘long’ but slightly increase the ‘slow’ to something a little punchier. I wouldn’t recommend spending a lot of time running at your target marathon pace, because this will be very fatiguing. But running just a tad slower than your marathon pace will continue to build strength, endurance and fitness as it’ll be at a pace faster than you’re normally used to.

To do this, add 15 – 30 seconds per mile to your marathon pace. If you’re targeting a 3:30-hour marathon (08:00mm pace), then you’ll complete these longer runs between 08:15-08:30mm.

Start with just a couple of 20-minute pieces at this pace, gradually increasing the duration as your fitness improves.

When it comes to training for a marathon, the most important thing is to focus. Be specific. Utilise the correct paces, duration of session and train on a course similar to the marathon.

Kit choices

Road shoes vs trail shoes. Well, it’s a bit of a no-brainer really. Road shoes tend to be lighter, which you will appreciate in the last few miles of a marathon. You won’t be needing those aggressive lugs on your trail shoes anyway, and you still have many options for cushioned road shoes if that’s what you’re after.

Otherwise, there’s not much difference in kit between ultras and road marathons. You can either embrace the short shorts or not. They’re not mandatory.

Nutritional strategies

Generally speaking, your training will reduce in volume but increase in intensity. This means you might find you shed a little fat and become a bit leaner (see more tips on How To Get Lean). That’s ok, but don’t let it go too far. You still need a lot of calories to replace those you’re burning. Although it’s an area of much contention, it is possible to train for ultras on a higher fat / lower carb diet, but for marathon training I personally believe you need to increase your carb uptake. When training at higher intensities, you need carbohydrates to fuel your sessions.

When it comes to the race itself, you’re not going to eat an awful lot. Whereas ultras have often been described as eating contests, a marathon is a different game. You’ll be running at an intensity which will make it difficult to consume food, let alone consume ‘real’ food, as we like to encourage at ultras. Instead, test which gels / chewable shots and energy drinks your stomach can cope with and go with that. You won’t need many but aiming to consume some sugar every 30 – 45 minutes is a good guide.


I’d urge you at some point to have a crack at a marathon. It really is a great distance, and the big city events are worth doing, even if it’s just once. Plus, your body and mind will tire of training purely for ultra running, and the change in structure will really freshen your training schedule. After it all, I’d bet you’ll be a better ultra runner for it, too.



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Entry Fee
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Date Range

Global - Virtual


A virtual race which can be run at any time shown on the dates shown, on any type of terrain in any country.

Suitable for

For runners from beginners to experienced as you choose your own course and challenge based on the guidelines and options set by the virtual race organiser.

Endurance - Multi-activity


An ultra distance race including at least two of the following activities such as running, swimming, cycling, kayaking, skiing and climbing. It may also include different climatic conditions (eg ice, snow, humidity, cold water, mud or heat).

Suitable for

Experienced multi-skilled athletes who have trained for the different activities included in this event. Admission to these races may be subject to receipt of a recent medical examination certificate. Check with the race organiser regarding entry requirements and any specialist equipment required such as a wetsuit, skis or a mountain bike.



Increase of up to 2000 metres with very challenging climatic conditions (e.g. ice, snow, humidity, heat or at high altitude)

Suitable for

Very experienced long distance ultra runners (min 3 years’ experience) or are doing regular long distance running (>50 miles) with elevation and conditions shown (where possible). Admission to these races is often subject to receipt of a recent medical examination certificate. Purchase of specialist kit is often recommended for these races.



Increase of up to 2000 metres with some challenging climatic conditions (e.g. ice, snow, humidity or heat)

Suitable for

Experienced runners who have completed at least 4 ultras in last 12 months, or are doing regular long distance running (>50 miles) with elevation and conditions shown (where possible). Admission to these races may be subject to receipt of a recent medical examination certificate. Check with the race organiser regarding entry requirements.



Increase of up to 1500 metres

Suitable for

Runners who have completed several ultra distances or similar events, or are doing long distance running regularly, with elevation shown.



Increase of up to 1000 metres

Suitable for

Runners who have completed at least one ultra in last 6 months or are doing long distance running (>26 miles) regularly, with elevation shown.



Very little change < 500 metres

Suitable for

First ultra event. Runners completing a marathon or doing regular long distance running (>26 miles) in the last 6 months.