A Guide to Surviving the UTS 100-Mile: Essential Hints and Tips

The Ultra-Trail Snowdonia 100mile (UTS) is a brutal test of endurance, featuring rugged mountain trails, over 10,000 metres of ascent, and technical terrain that pushes even seasoned ultra runners to their limits. The race holds many fond memories for me and has been a significant part of my evolution in ultra running. My first experience with the race was in 2019 when I participated in the original 50-mile course. In 2021, I made a last-minute entry into the 100k Capel Curig course after surprising myself in the Lakeland 50, following a long layoff due to the COVID pandemic and a broken toe. In 2023 and 2024, I tackled the 100-miler, and in 2025, I’ll return to take on the 100k once again.

Each time I’ve participated, the event has been a rewarding experience. I’ve watched it grow from a grassroots race with a few hundred entries across all categories to the major event it is today as part of the UTMB circuit.

The challenge of Ultra Trail Snowdonia is reflected in its high DNF (Did Not Finish) rates. In the 2024 100-miler, the DNF rate was 62%, with only 99 finishers out of 260 participants. Similarly, in 2023, the DNF rate was 59%, with 96 finishers out of 231. These figures underscore the race’s difficulty.

Environmental Variables

In both 2023 and 2024, heat was a significant factor. Temperatures reached up to 25°C with little to no breeze. After a cold winter, many participants were unprepared for the sudden change in temperature. For a UK-based mountain race, dedicated heat acclimatisation isn’t usually part of pre-race training. This gave an advantage to overseas participants and those experienced in summer alpine races, where temperatures of 25–30°C (or even higher) are more common.

While everyone’s tolerance to heat varies, robust training can enhance this tolerance in several ways:

• Improved Stroke Volume: Training strengthens the heart, enabling more efficient blood circulation to muscles and skin for cooling.
• Reduced Heart Rate: A lower resting and exercise heart rate improves performance and comfort in heat.
• Sweat Mechanism Efficiency: Training promotes earlier onset of sweating and higher sweat rates, aiding cooling during prolonged efforts.
• Increased Mental Resilience: Repeated exposure to training stress prepares athletes for the psychological discomfort of heat.

Robust training can also mitigate gastrointestinal (GI) issues caused by splanchnic hypoperfusion—the reduced blood supply to the GI tract during exercise. Blood flow to the GI tract decreases by up to 80% compared to resting levels as blood is redirected to active muscles and the skin. Comprehensive training can help reduce the severity of GI problems.

Even without specific heat training, thorough preparation enhances your ability to deal with high temperatures and improves performance in any conditions.

Additional Tips for Heat Management

1. Use natural water sources en route to avoid dehydration and cool down. For instance, applying a cold, wet buff to your wrists cools blood flowing through the radial artery and is more effective than cooling the head.
2. Eat salty foods at aid stations to maintain electrolyte balance and avoid hyper- or hyponatremia.

Underfoot Conditions

The terrain in Snowdonia presents its own challenges. Although the course lacks the longer climbs of alpine races like UTMB, it compensates with technical sections, including boggy marshland, scree, and boulder fields. This arguably makes it a harder proposition. Runners with experience in fell running or hiking in UK mountains will have an advantage.

A key preparation strategy, alongside fitness training, is enhancing mountain movement skills. Ultra races differ significantly from marathons, as each course is unique and demands specific preparation.

Course Checkpoints and Timeouts

Early checkpoints often have the most severe cut-offs, which can result in participants timing out early in the race. I observed many runners struggling with descents, moving tentatively and inefficiently, which significantly slowed their progress. To address this:

• Recce the Course: Focus on the first few checkpoints to understand pacing requirements.
• Train on UK Mountain Terrain: Fell running or hiking on rugged terrain builds confidence and efficiency.

Living in the Peak District allowed me to incorporate 52,867m of elevation gain before the 2024 race, ensuring I was accustomed to rough terrain and that my legs were conditioned for both ascents and descents. Training with poles can also be beneficial, but practise their use and storage before race day. Personally, I use loops on a race belt to stow poles quickly, but other methods, like quivers or straps on a vest, may suit you.

Foot Management and Blister Prevention

Foot management is critical for any ultra race, especially for UTS. Key considerations include:

1. Footwear: Choose shoes that suit your individual needs. While some recommend sizing up for swelling, I’ve found this leads to more issues. I prefer a snug fit, like the Salomon S/Lab Ultra. Experimentation is essential to find what works for you.
2. Lubrication and Socks: In 2024, I carried extra socks and anti-friction cream, applying them at checkpoints. Toe socks are particularly effective for preventing blisters between the toes.
3. Foot Taping: Learning to tape your feet can help prevent hotspots and blisters. During the 2024 Swiss Peaks 380, a chiropodist taped problem areas at the 100-mile mark, which alleviated issues despite challenging conditions, and I continued to utilise this service at lifebases throughout the race.

Snowdonia’s boggy terrain exacerbates underfoot problems, so preparation is vital. Experiment with methods like foot lubrication, taping, and sock changes during training to determine what works best. There is always good practice but no absolutes, and conditions and individuals will dictate the strategy employed.

Pre-Race Foot Care

There are two schools of thought for foot preparation:

• Toughening the Feet: Gradually expose them to rough conditions.
• Moisturising and Removing Hotspots: Maintain healthy skin and remove calluses.

I’ve tried both and currently favour the latter, but it’s worth experimenting. The book Fixing Your Feet by John Vonhof is an excellent resource for learning foot care techniques: https://www.fixingyourfeet.com/.

Course Marking

The course marking is largely very good but, as with all these types of events, there are often areas of the course where flags might be sparse or not visible due to darkness or mist, despite their reflective qualities. In 2021, a competitor who was just behind me pulled out at the final checkpoint just after the Carnedds because their GPX watch had depleted its battery. They were unable to utilise a map and compass as a backup and lacked the confidence to proceed. It is always useful to have a backup strategy, and basic map skills and the ability to use a compass are important in the mountains. Additionally, picking a GPX device with a long battery life will be very helpful. Since 2022, I’ve been using a Coros Vertix 2 due to its excellent battery life, and the Garmin equivalent would be the Enduro range.

Nutrition

Gastrointestinal issues can become a huge problem in ultras due to the reasons alluded to earlier. The solution is to practise your nutrition strategy during training and learn what types of foods you can tolerate. For me, I use gels and bars (e.g., Voom Bars and Kendal Mint Cake) in my race vest and aim to eat well at aid stations.

At aid stations, the food available at UTS included:

• Vegetarian Chilli: Multiple portions for substantial energy.
• Soup: Easily digestible and hydrating.
• Nuts, Crisps, and Sandwiches: Salty foods to replace lost electrolytes.
• Pasta: A solid carbohydrate source.

My usual system is to stash poles in my race belt on entering an aid station and have my soft flasks ready to fill. I either gather food to eat on the move or stop longer to treat my feet. At aid stations, most UTS setups include items like Naak Bars, wafers, and electrolyte drinks, so it’s wise to test these products beforehand.

Robust cardiovascular training enhances the availability of oxygen to aid digestion, so thorough training and fitness will always help.

Foods to Practise Before Race Day

When preparing your race-day nutrition plan, it’s essential to include a variety of food types in training to determine what works best for you. A balanced approach might include:

Real Food Options:

• Pretzels
• Rice balls
• Sandwiches (e.g., peanut butter, cheese, or jam)
• Soup

Engineered Foods:

• Gels
• Chews
• Energy bars

Sweet Foods:

• Kendal Mint Cake
• Chocolate
• Dried fruit

Salty Foods:

• Nuts
• Crackers
• Salty crisps

Savoury Foods:

• Pasta
• Potatoes
• Broth-based soups

A good rule of thumb is to aim for ~250 calories per hour and adjust based on individual needs. A suggested macronutrient breakdown is 50–60% carbohydrates for sustained energy, 20–30% fats for longer efforts, and 10–20%

The Course

When I consider the course, the first 50 km from Llanberis to Capel Curig involves 3,292 m of elevation gain. My strategy is to build a time buffer during this initial section. On both occasions, I reached this part around 10 pm, maintaining a steady, relaxed pace that didn’t burn me out. This approach allowed me to arrive fresh and ready to tackle the first night with a 4-hour time buffer.

From Pen y Pass to Glan Dena via Glyder Fawr and from Glan Dena to Capel Curig are two of the most difficult legs of the race, but they’re also two of my personal favourites. You might spot ponies on the Carneddau, and the ridge line is spectacular. They mentioned eliminating an aid station after the Carneddau descent, but there was still a small aid station offering Naak products and limited water. Additionally, there are plenty of natural water sources on this leg.

At Capel Curig, I took the time to apply lubricant to my feet and spent longer at this aid station than the previous ones. The first section of night one involves climbing the rocky steps and slabs of Moel Siabod, which requires scrambling over potentially slippery rocks in the dark. This is a good section to recce, especially as it’s likely to be done in the dark on the 100-mile route.

The first night was manageable in terms of sleep deprivation, aided by clear skies and the northern lights. I arrived at Croesor around 6 am, extending my buffer to 6 hours. This was another opportunity to dry and lubricate my feet, change socks, and restock gels and bars from my drop bag. I decided to keep the same shoes, knowing the next section would plunge me into bogs.

The section over Cnicht and towards Gwastadanas Farm is tough on the feet and often where problems begin. I’d advise spending time at this checkpoint to dry and lubricate your feet. Setting off too quickly from here isn’t advisable. This checkpoint was busy, and after spending much of the night with one other person, I suddenly found myself on single tracks with crowds of 50k runners, who were much fresher, having just started.

The section from Gwastadanas to Beddgelert should be straightforward, but if you’re experiencing foot issues, it can be frustrating and take longer than expected. I arrived at Beddgelert just after noon. This is a crucial checkpoint where many drop out. Spend time here to refuel, dry your feet, apply lubricant or tape, and consider carrying an extra soft flask, as the next section involves a long, steep climb with technical terrain and no easily accessible water sources.

After leaving Beddgelert, I faced the full heat of the sun on the climb up Moel Hebog. This section crosses stunning, remote scenery and culminates in the picturesque yet technical descent of the Nantlle Ridge. By the time I reached Rhyd Ddu, I had covered 128.4 km. I arrived just before 7 pm, with blister issues worsening, ready to tackle the ascent of Snowdon and the second night.

At Rhyd Ddu, I removed my shoes and socks, dried my feet, and reapplied lubricant. I also had a couple of bowls of vegetarian chilli and rice to fuel up for the final night. This section often sees dropouts due to exhaustion from the Beddgelert-to-Rhyd Ddu leg. Although I felt fresh apart from the blisters, they were progressively slowing me down from Gwastadanas onwards.

The final night covered just under 36 km but was tough, with boggy sections and significant climbs up Mynydd Mawr and Moel Eilio, which are brutal on tired legs. Sleep deprivation becomes a factor by night two. Many competitors use emergency survival bags to rest briefly. I didn’t sleep in 2023 and only took a 5-minute power nap in 2024. The morning sun always energises me, as does knowing Llanberis is near.

Despite agonising foot pain, I gritted my teeth and ran the final section, desperate to finish. I crossed the line at 7:29 am (42 hours and 29 minutes) in 2024 (Cut off 48hrs). While happy with my success, I’d hoped for a faster time, but the foot issues slowed me down. The early time buffer I built was invaluable in the later stages.

UTS is a stunning but extremely challenging race. I’m looking forward to tackling the 100k this year and hope to finish in good time. I also look forward to meeting other participants along the way (feel free to say ‘Hi’ if you spot me 😊) The mountains of Snowdonia mean a lot to me, and events like UTS have been stepping stones toward other races, such as the Swiss Peaks 380 in September 2024 (Check out my YouTube film here: https://www.youtube.com/watch?v=SmoTaWMXd8c&t=2314s).

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I’m a UESCA-certified Ultra Running Coach and Off-Road Run Leader with UK Athletics. I offer personalised online coaching for all levels and guided runs in the Peak District. Explore my website for details or email me to arrange a free consultation to discuss a coaching plan to help you succeed in UTS or other events.

Good luck, and thanks for reading! Please feel free to leave a comment below!