UTS 100 Mile Guide: Training, Fuelling & Tips from Mark Darbyshire

The UTS 100 Mile is one of the toughest ultra trail races in the UK. Taking runners through the mountains of Eryri (Snowdonia), the race combines huge amounts of climbing with technical descents, exposed ridges, rough trails and hours of relentless mountain running.

VOOM athlete Mark Darbyshire knows exactly what it takes to succeed at UTS. After winning the UTS 100K in 2021 and suffering a DNF in the 100-mile race in 2023, Mark returned in 2024 determined to put things right.

He did exactly that, taking victory in the UTS 100 Mile.

We caught up with Mark to find out how he trained for UTS 100, how he fuelled a 100-mile mountain race and what advice he’d give to anyone preparing to take on the course.

What Is the UTS 100 Mile?

The Ultra-Trail Snowdonia by UTMB is an ultra running event held in Eryri (Snowdonia), Wales, with races taking runners through some of the most spectacular and demanding mountain terrain in the UK.

The UTS 100 Mile is the longest race of the weekend and is a serious test of endurance. Steep climbs, technical descents and difficult terrain mean success requires much more than simply being able to run 100 miles.

Training, strength, pacing, fuelling and experience in the mountains can all make a huge difference.

Mark Darbyshire’s UTS Running Experience

Mark had been running ultras for around ten years when he won UTS 100, but his relationship with the race hadn’t always gone smoothly.

“My dad moved to the Brecon Beacons and I’ve been running ultras for about 10 years. This was my fourth year in a row at UTS.

“I won the 100K in 2021, then attempted the 100 miler in 2022 when it was unfortunately cancelled because of bad weather. I then DNF’d the 100 miler the following year after blowing my quads.”

Rather than putting him off, that DNF gave Mark another reason to return.

“Pretty much the day after I DNF’d, I knew I had to come back and put it right.”

Why Take On the UTS 100 Mile?

For Mark, part of the attraction is simple: it’s a huge mountain race on some of his favourite terrain.

“It’s a big UK event and I love the mountains of Snowdonia.

“Mike Jones got it spot on when he described the route as ‘beautiful beyond belief, savage beyond reason’. I also like the level of competition it’s started to attract, with lots of top runners.”

It’s that combination of beautiful mountain terrain and an incredibly demanding course that has helped establish UTS as one of the standout events in UK ultra running.

How to Train for the UTS 100 Mile

Training for UTS isn’t just about accumulating as many miles as possible. The steep and technical nature of the course means runners need to prepare specifically for the demands they’ll face in the mountains.

Mark’s everyday running provides a consistent endurance base.

“I run to work and back, which is about 10 miles a day, but I don’t log miles on my watch or use Strava.”

Strength Training for UTS 100

After his quads caused problems during his previous attempt, Mark knew strength work had to become a bigger part of his preparation.

“Specifically for UTS, I did some extra strength work to harden up the quads after what happened the year before.”

Strong quads are particularly important for coping with the repeated steep descents. Over 100 miles, the accumulated muscular damage from descending can become just as significant as the effort required to climb.

Get Plenty of Time in the Mountains

Mark also made his training as specific to UTS as possible.

“I put in a fair few long, slow mountain days either in the Brecon Beacons or Snowdonia.”

For runners preparing for UTS 100, spending time on steep, technical terrain can help develop the strength, confidence and movement skills that are difficult to replicate on flatter trails.

What Is the Toughest Part of UTS 100?

With such a demanding course, there are plenty of difficult sections, but one stood out to Mark.

“The biggest challenge this year was probably the night section from Cnicht to Gwastadannas Farm.

“It’s rough, boggy and very difficult to find any rhythm. Although it’s not that long, it seems to drag on for ages.”

Running through the night adds another challenge to an already difficult race. Pace can slow, tiredness builds and technical terrain becomes harder to negotiate in the dark.

Mark’s advice is not to panic if you hit a difficult patch.

“Don’t worry too much about feeling a bit rough at night. More than likely, things will improve when the sun comes up.”

Mark’s Favourite Part of the UTS 100 Course

Mark’s favourite section was also significant because it was where his previous race had unravelled.

“My favourite part this year was probably the Moel Hebog and Nantlle Ridge section.

“It’s where the wheels fell off the year before, so it was pretty satisfying to feel strong during this section. Plus, it’s stunningly beautiful with both mountain and sea views.”

Coming back stronger to the exact section that had caused problems previously made it one of the highlights of his winning run.

The Best Moment of Winning UTS 100

After 100 miles of mountain running, Mark’s standout moment came when he finally knew the victory was his.

“The best moment was probably flying down the last descent heading towards Llanberis knowing that the hard work had paid off.

“I also really enjoyed running with Andy Berry for the first 60K. Top fella!”

How to Fuel for the UTS 100 Mile

Getting your nutrition right becomes increasingly important as race duration increases, and a 100-mile ultra requires a fuelling strategy you know your stomach can tolerate.

Mark kept his pre-race food straightforward.

“I had porridge and yoghurt for breakfast and some sandwiches for lunch.”

Once the race started, he preferred to fuel according to how he felt rather than following a rigid carbohydrate target.

“During the race I never really have a specific plan for carbs per hour. I just go with feel. On average, I probably had about one VOOM Pocket Rocket per hour.”

Pocket Rockets provided Mark with a compact and easy-to-carry source of carbohydrate while moving through the mountains.

Hydration and Electrolytes During UTS

Conditions were warm, making hydration another important consideration.

“I also had plenty of VOOM Rapid Electrolyte Drink at the crew stops. I knew this would be important because of the heat.”

Hydration requirements can vary significantly between runners, so your strategy should take into account conditions, sweat rate and how much fluid you’re comfortable consuming while running.

Using Real Food During a 100-Mile Ultra

Mark didn’t rely exclusively on sports nutrition.

“At the aid stations and crew stops I tried to eat real food, mainly pizza, cheese and pickle sandwiches, and yoghurt with honey.

“That gave me a good balance of carbs, some protein and some fats.”

For very long ultras, having a range of familiar foods and flavours can make it easier to continue eating as the hours add up.

The most important thing is to practise your race nutrition during training. UTS 100 is not the place to discover that your stomach doesn’t agree with your chosen fuel.

Essential Kit for the UTS 100 Mile

After several years racing at UTS, Mark picked out three pieces of kit that made a particularly big difference.

1. Trail running shorts with plenty of storage

“My Decathlon trail running shorts are very comfortable with loads of built-in pockets for storing nutrition and my phone.”

Easy access to food is particularly useful in an ultra, allowing you to keep fuelling without constantly stopping to dig through your running pack.

2. A GPS watch with mapping

“My COROS Apex 2 Pro has a proper map – and I could get lost in a phone box!”

Reliable navigation becomes especially valuable when you’re tired, running at night or moving through difficult mountain terrain.

3. A good headtorch

“My Fenix headtorch helped massively during the night. Being able to see clearly makes a huge difference on rough terrain.”

Mark Darbyshire’s Top 3 Tips for UTS 100

If you’re thinking about entering UTS 100, Mark’s advice is simple:

1. Recce the UTS 100 course

“Get out on the course because it’s technical and steep, but also pretty unique.”

The more familiar you are with the terrain, climbs and descents, the fewer surprises you’ll encounter on race day.

2. Start slower than you think

“Start slowly and build into the race. It’s often easier said than done, but it pays off big time in the second half. It’s a long old race!”

Pacing a 100-mile ultra requires patience. Saving energy early can make an enormous difference when the race reaches its decisive final stages.

3. Don’t panic when things get tough

“Don’t worry too much about feeling a bit rough at night. More than likely things will improve when the sun comes up.”

Low points are part of ultra running. Feeling bad at one stage doesn’t necessarily mean your race is over.

Training for UTS 100? Prepare for the Course, Not Just the Distance

Mark’s victory shows that preparing for the UTS 100 Mile is about much more than being able to cover a huge distance.

Specific strength work helped prepare his quads for the relentless descending. Long days in the mountains prepared him for the technical terrain. Course knowledge gave him confidence in sections that had caused problems before, while consistent fuelling and hydration helped him keep moving through 100 miles.

Perhaps most importantly, he returned after a DNF, learned from what went wrong and used that experience to come back stronger.

For anyone preparing for UTS 100, Mark’s advice can be boiled down to three things: get onto the course, respect the distance and don’t start too quickly.

And when things inevitably get difficult? Keep moving. The sun might be about to come up.