If you’ve ever crossed the finish line of a half marathon or full marathon and wondered, “What’s next?” — you’re not alone. Many runners feel the urge to push further, to explore trails, test their limits, or simply try something new. But not everyone is ready (or willing) to jump straight into a 100K ultramarathon. That’s where the sub-ultra marathon comes in.
Sub-ultras are the perfect stepping stone between traditional road races and the demanding world of ultras. Whether you’re aiming for a scenic 30K trail run or dipping your toes into your first 50K, sub-ultras offer a balanced challenge: more endurance and adventure, without the overwhelming distance.
A sub-ultra marathon is any footrace longer than a half marathon but shorter than a traditional ultramarathon. Most commonly, it refers to races between 25 kilometers and 50 kilometers, with some trail marathons (~42K) also considered part of this group.
Think of sub-ultras as the “gray zone” between a marathon (42.195 km) and the world of ultras (which technically starts at anything over 42.195 km, but often begins in earnest at 50K or 50 miles).
🧭 Typical Sub-Ultra Distances:
25K (~15.5 miles)
30K (~18.6 miles)
Trail marathon (~42K / 26.2 miles)
50K (~31 miles)
These races are especially popular on trails but can also be found on roads. They offer more time-on-feet, elevation gain, and fueling practice than shorter races, but without the logistics and training complexity of 100K+ ultras.
🗣️ In simple terms: A sub-ultra marathon is longer than a marathon training run, but shorter than a true ultra.
Sub-ultras are perfect for runners who want a new challenge without committing to overnight runs, drop bags, or 12-week wilderness adventures. They’re also a favorite among trail runners who enjoy shorter, more technical terrain.
🟩 3. Common Sub-Ultra Distances
Unlike the rigid definition of a marathon (42.195 km), sub-ultra races come in a wide variety of distances — offering flexibility for runners of all levels. Here’s a breakdown of the most common sub-ultra distances you’ll encounter:
🔹 25K (15.5 miles)
Often seen as a “longer long run,” the 25K distance is ideal for half marathoners looking to go beyond. These races usually take 2–4 hours to complete and may be found in trail festivals or as shorter options within larger ultra events.
✅ Best for: Intermediate runners transitioning from road to trail, or building toward longer efforts.
🔹 30K (18.6 miles)
A classic “in-between” distance that has become popular in both road and trail scenes. In Japan and Canada, 30K road races like the Kumanichi 30K or Around the Bay 30K are famous test events for marathon training. On trails, this is where elevation and terrain start to matter more.
✅ Best for: Road marathoners seeking a new challenge; trail runners working up to their first marathon.
🔹 Trail Marathon (~42K / 26.2 miles)
While technically a marathon, many trail races at this distance feel much more like ultras — with major elevation gain, rough terrain, and longer finish times. A 42K trail race can easily take twice as long as a flat road marathon.
✅ Best for: Runners with marathon experience who want a taste of ultra-style terrain without the extra distance.
🔹 50K (31 miles)
The gateway to ultrarunning. Many runners consider 50K their first “true ultra,” yet it’s still close enough to a marathon that training is manageable. Courses vary: some are rolling and runnable, others steep and mountainous.
✅ Best for: Marathon finishers ready to go longer, or trail runners eager for a full-day experience.
Each distance brings a unique blend of endurance, strategy, and mental strength — all without requiring the same level of gear, crew, or commitment as longer ultramarathons. That makes sub-ultras an appealing and accessible next step.
🧠 Pro tip: Before choosing a sub-ultra race, look at elevation gain and course profile — they matter as much as distance.
🟩 4. Sub-Ultra vs Marathon vs Ultramarathon
At first glance, the difference between a marathon, sub-ultra, and ultramarathon might seem like just a matter of distance. But in reality, each brings its own training demands, pacing strategy, terrain challenges, and mental game. Understanding these differences will help you choose the race that matches your goals and fitness level.
A sub-ultra may take longer than a marathon depending on terrain and conditions. For example, a hilly 42K trail race could take 6+ hours, while a flat 50K road race might be done in under 4.5.
⛰️ Terrain & Elevation
Marathons are usually held on paved, measured roads.
Sub-ultras often take place on trail courses with moderate to serious elevation.
Ultras go deeper into the wilderness: remote trails, overnight running, major altitude gain.
🧗 Note: A 30K trail race with 1,500m of climbing may be harder than a flat 50K road race.
⏱️ Pacing Strategy
Marathon: Pacing often aims for negative splits or maintaining a steady pace.
Sub-Ultra: Runners shift to effort-based pacing. Hills, weather, and trail conditions dictate speed.
Ultra: Power hiking, rest stops, and strategic walking are built-in.
🧠 Mental shift: Sub-ultras teach you to let go of pace and focus on rhythm, terrain, and fuel.
Sub-ultras are often the first races where serious fueling matters. A bonk at km 35 in a 50K can cost you dearly if not planned.
🧠 Mental Challenge
Marathons test your speed and discipline.
Sub-ultras challenge your ability to adapt to terrain, fatigue, and weather.
Ultras test your endurance and resolve over many hours or days.
🌟 Sub-ultras are the “sweet spot” for runners who want a tough but realistic adventure — without giving up their weekend or needing a support crew.
🟩 5. Why Sub-Ultra Marathons Are Great for Beginners
You don’t have to be a hardcore ultrarunner to experience adventure, challenge, and trail magic. Sub-ultra marathons offer the perfect entry point into the world of long-distance running — without demanding the extreme distances, gear, or time commitment of traditional ultras.
Here’s why so many runners choose sub-ultras as their first step beyond the marathon.
✅ Manageable Yet Rewarding Distance
Sub-ultras (typically 30K to 50K) are long enough to test your endurance, but not so long that they require months of specialized training. If you’ve finished a half or full marathon, you’re already halfway there.
💡 For many runners, the 50K is the “safe” first ultra – only 8K beyond a marathon, but mentally a big leap.
✅ Less Pressure, More Exploration
Unlike road marathons with strict pacing and crowd expectations, sub-ultra races — especially on trails — allow you to move at your own rhythm. Walk when needed. Soak in the views. It’s not about a personal best; it’s about personal discovery.
✅ More Scenic & Social
Sub-ultra trail events are often held in national parks, mountains, or coastal paths. The experience is more immersive and community-focused. Aid stations feel like parties. Runners encourage each other. It’s a world away from the stress of big-city races.
✅ Minimal Gear Required
While longer ultras require drop bags, headlamps, and specialized nutrition, most sub-ultras can be done with:
🧢 No need for crew, camping, or technical gear – just show up ready to run.
✅ Gateway to the Ultra World
Many elite ultrarunners began with sub-ultras. These races teach pacing, fueling, and terrain awareness — essential skills for longer adventures later.
🗺️ Sub-ultras are your map-reading level before you tackle the full expedition.
✅ More Accessible Than You Think
Don’t let the name fool you. Many sub-ultra races are beginner-friendly, with:
Generous cut-off times
Excellent race support
Well-marked routes
Varied terrain options (not all are steep or technical)
🗣️ Runner Tip: Look for local sub-ultra trail races around 25–35K as your first. You’ll gain confidence without overreaching.
🟩 6. Popular Sub-Ultra Marathon Races Around the World
Sub-ultra marathons are gaining popularity across the globe — from snowy mountains in Switzerland to scenic coastal trails in California. Whether you prefer road or trail, there’s a race that fits your pace and personality.
Here’s a taste of the world’s most iconic and beginner-friendly sub-ultra events.
🌍 Trail Sub-Ultra Races
🏔️ Sierre-Zinal (Switzerland) – 31K
One of the most prestigious mountain races in Europe, held every August in the Swiss Alps. With over 2,000 meters of elevation gain, this race is short but intense. Stunning views of five 4,000-meter peaks make every step worth it.
⛰️ Perfect for experienced marathoners looking for vertical challenge.
🏞️ Broken Arrow Skyrace 23K (USA, California)
Held in June near Lake Tahoe, this course includes alpine trails, snow crossings, and panoramic views. The 23K is the “starter” version of the ultra-length 46K Skyrace.
🌄 Great for first-timers craving high-altitude adventure.
🌲 Crested Butte Ultra 35K (USA, Colorado)
A gorgeous September trail race through aspen groves and wildflower meadows in the Colorado Rockies. A manageable challenge for those acclimating to altitude.
🍁 Beginner-friendly distance with serious trail cred.
🏜️ Zion 50K (USA, Utah)
Run through red rock canyons near Zion National Park in February. A scenic, smooth-entry trail ultra that draws road runners and nature lovers alike.
☀️ Popular first 50K thanks to mild weather and smooth trail.
🛣️ Road Sub-Ultra Races
🛤️ Around the Bay 30K (Canada)
The oldest road race in North America (since 1894), held every March in Hamilton, Ontario. A beloved pre-marathon tune-up race with serious community spirit.
🏁 Flat, fast, and full of history.
🎌 Kumanichi 30K (Japan)
A February race with elite status — past world records have been set on this 30K road course. Great for pacing, testing, and sharpening your marathon form.
🧪 Ideal for runners wanting a fast and focused challenge.
🌳 Ohme-Hochi 30K (Japan)
A scenic, hilly race west of Tokyo in early spring. With forests, community vibes, and a festive finish, it’s a staple in Japan’s road running calendar.
🎎 Combines beauty and difficulty for the perfect sub-ultra test.
📊 Summary Table
Race Name
Distance
Location
Terrain
Month
Sierre-Zinal
31K
Switzerland
Trail
August
Broken Arrow 23K
23K
USA (California)
Trail
June
Crested Butte 35K
35K
USA (Colorado)
Trail
September
Zion 50K
50K
USA (Utah)
Trail
February
Around the Bay 30K
30K
Canada (Ontario)
Road
March
Kumanichi 30K
30K
Japan (Kumamoto)
Road
February
Ohme-Hochi 30K
30K
Japan (Tokyo)
Road
February
Each of these races offers a unique gateway into sub-ultra running. Some test your lungs on alpine climbs. Others hone your speed on rolling roads. But all of them have one thing in common: they welcome new challengers with open arms.
🌎 Whether you’re racing through forests or city streets, a sub-ultra is waiting for you.
🟩 7. How to Train for a Sub-Ultra Marathon
Training for a sub-ultra marathon isn’t about running farther — it’s about training smarter. Whether your goal is a 30K road race or a 50K trail ultra, preparation is key to avoiding burnout, injury, or the dreaded DNF (Did Not Finish).
Here’s how to structure your training so you show up strong, steady, and ready to enjoy the adventure.
🗓️ Training Duration: How Many Weeks?
For most runners:
🟢 30K: 10–14 weeks of focused training
🟢 50K: 14–18 weeks (especially if it’s trail or has elevation)
If you already have a solid base (running 3–4 times/week, long runs of 10–15 km), you’re in a great position to start.
🧱 Build your training on consistency, not intensity.
🧩 Weekly Structure (Typical)
A balanced sub-ultra training week might look like:
Day
Workout Type
Monday
Rest or cross-training
Tuesday
Moderate run + strides
Wednesday
Easy run or strength
Thursday
Tempo or hill repeats
Friday
Rest or mobility work
Saturday
Long run (critical!)
Sunday
Easy recovery run
Key Workout: Long runs on weekends. Start around 12–15K and build to 28–35K (or time-based, e.g. 3–4 hours).
Hill Work: Crucial if your race has elevation. Include hill repeats or hilly trail runs weekly.
Back-to-Back Runs (for 50K): Simulate race fatigue by doing a long run Saturday and a medium run Sunday.
🥤 Fueling During Training
Unlike marathons, sub-ultras require fuel practice during your long runs. Your stomach needs to learn how to handle food on the move.
Aim for 150–250 kcal/hour (gels, chews, real food)
✅ Start where you are – don’t rush to 50K if you haven’t mastered 20K+
✅ Go by time, not distance – especially on trails, measure your long runs in hours
✅ Walk when needed – especially uphill; pacing is effort-based
✅ Listen to your body – rest is part of training
✅ Simulate race terrain – if your race is on trails, train on trails
🧠 Mindset Shifts
You’re not racing pace anymore — you’re racing time on feet
You’ll need patience, presence, and a plan
Mental fatigue is real — long runs are also for testing your willpower and fueling strategy
🗣️ Coach Tip: “The best sub-ultra finishers aren’t always the fastest runners — they’re the most consistent and prepared.”
🟩 8. Essential Gear for Sub-Ultra Runners
Unlike longer ultramarathons that may require elaborate kits, drop bags, and mandatory gear lists, sub-ultras usually keep it simple — but having the right essentials can make or break your race day.
Here’s what you actually need to stay safe, fueled, and focused between 30K and 50K.
👟 1. Trail-Appropriate Running Shoes
If your race is on trails, road shoes won’t cut it. Look for:
Aggressive lugs for grip
Rock plate for protection
Wide toe box for long-run comfort
🧠 Tip: Break in your race shoes at least 3–4 weeks before race day.
🎒 2. Hydration Vest or Belt
Most sub-ultras require carrying your own water, especially trail races.
Options:
Hydration vest (2 x 500ml flasks or 1.5L bladder)
Hydration belt (for shorter 25–30K races)
Look for:
Chest pockets for gels, salt tabs
Comfort fit (no bounce!)
Easy access to fuel while running
🕒 3. GPS Running Watch
Tracking distance, time, and heart rate is useful — but for trails, elevation and route guidance can be a game changer.
Look for:
GPS + elevation tracking
Custom intervals
Real-time pace alerts (especially for road races)
🌧️ 4. Lightweight Rain Shell or Wind Jacket
Weather can change quickly in mountain or coastal trail races. A light, packable shell:
Protects from wind, rain, or cold starts
Can be tied around the waist or stuffed in vest
⛅ Especially important if your race climbs to exposed terrain.
🧭 Sub-ultra races are a perfect place to practice your race-day gear strategy — without going full expedition mode.
🟩 9. Tips for Race Day Success
Race day isn’t just about how well you trained — it’s about how well you execute. Sub-ultras require more strategy and adaptability than a standard marathon, especially if trails, hills, or longer durations are involved.
Here are proven tips to help you finish strong and enjoy the experience.
⏱️ 1. Start Slower Than You Think
Don’t get caught up in the adrenaline. Even experienced runners blow up by pushing too hard in the first 5K.
🧘 Start conservative, finish powerful.
Run at a conversational pace in the first third
If on trail, walk steep climbs early to save energy
🧃 2. Stick to Your Fueling Plan
The biggest cause of DNFs in sub-ultras? Not eating or drinking enough.
Fuel early and often – don’t wait until you’re hungry
🔄 Practice your fueling in training — race day is not the time to experiment.
🚰 3. Master the Aid Stations
Don’t just “wing it.” Know what’s available and when.
Check the course map and aid station locations
Use your own fuel in between stations
At the station: drink, refill, move on
⏳ Minimize time spent — efficiency adds up.
🧠 4. Prepare for Mental Dips
Even in shorter sub-ultras, you’ll hit tough patches. That’s normal.
Use mantras or music
Break the race into chunks (e.g., 10K segments)
Remind yourself: “This is temporary.”
💬 “Strong mind, strong finish.”
👟 5. Know When to Walk
Yes — walking is allowed and encouraged on steep climbs or during fueling.
Hike hills to preserve energy
Walk while eating to aid digestion
Power walk breaks can reset your rhythm
🥾 Especially on trails, hiking ≠ weakness — it’s smart pacing.
🕖 6. Dial in Your Morning Routine
Don’t leave your morning to chance:
Wake up 3+ hours before the race
Eat a familiar breakfast (carbs + a little protein)
Hydrate early (but don’t overdrink)
Use the restroom… then go again!
📸 7. Soak It All In
You trained for weeks — now enjoy it.
Smile at aid stations
Thank volunteers
High-five fellow runners
Stop for a selfie if the view blows you away (just not every km 😄)
🏁 Sub-ultras are as much about the journey as the finish line.
🟩 10. Conclusion
Sub-ultra marathons are more than just a stepping stone — they’re a destination in their own right.
With distances that challenge your endurance, but don’t overwhelm your life, sub-ultras are the sweet spot for runners ready to go beyond the road, the routine, and the ordinary. Whether you’re chasing a personal milestone, exploring nature on trails, or just craving something new after your last marathon, this is your sign: you’re ready.
You don’t need to be elite. You don’t need to be fast. You just need to be curious — and consistent.
🎯 Sub-ultras are where ordinary runners do extraordinary things.
👉 Your Next Steps:
🏃♀️ Pick your first sub-ultra race
📅 Start training smart
🧠 Learn what gear you really need
💬 What About You?
Are you planning your first 50K?
Already raced a 30K and want to share your story?
Have questions about fueling or pacing?
Drop your thoughts in the comments below — let’s start a conversation.
🧭 You’ve read the guide — now go find your sub-ultra adventure.
❓ Frequently Asked Questions
What is a sub-ultra marathon?
A sub-ultra marathon is a footrace longer than a half marathon but shorter than a traditional ultramarathon — typically between 25K and 50K.
Is a 50K considered an ultramarathon or a sub-ultra?
Technically, 50K is the first official ultramarathon distance, but it’s often grouped with sub-ultras due to its similarity to marathons in training and logistics.
Who should run a sub-ultra?
Runners who have completed a half or full marathon and want to take on a new challenge without jumping into extreme ultras.
How long does it take to train for a sub-ultra marathon?
Most runners train for 10–14 weeks for a 30K and 14–18 weeks for a 50K, depending on experience and terrain.
Can I walk during a sub-ultra race?
Absolutely. Walking steep hills or taking short breaks is common, especially on trail courses.
Do I need special gear to run a sub-ultra?
You’ll likely need trail shoes, a hydration vest or belt, and fuel — but no complex gear is required for most races.
What’s the difference between a trail marathon and a road marathon?
A trail marathon often has more elevation, technical terrain, and takes significantly longer to complete than a flat road marathon.
How do I fuel during a sub-ultra race?
Eat 150–250 kcal per hour and hydrate regularly. Use gels, chews, or small real food items — and practice in training.
What’s the most popular sub-ultra distance?
30K and 50K are the most common sub-ultra race distances worldwide.
Can I run a sub-ultra without running a marathon first?
Yes, especially if you have a strong endurance base or have completed long trail events or back-to-back long runs.
Are sub-ultras beginner-friendly?
Many sub-ultras are designed for beginners, with generous cut-offs and supportive environments — especially in trail events.
What’s the elevation like in a typical sub-ultra trail race?
It varies. Some are flat and runnable; others, like Sierre-Zinal, have 2,000m+ of elevation gain.
How do I choose my first sub-ultra race?
Consider distance, terrain (road or trail), elevation, climate, and available support. Start with local or well-reviewed beginner-friendly events.
Do I need trekking poles?
Only for steep mountain races or personal preference. Most sub-ultras don’t require them.
Is road or trail better for a first sub-ultra?
Trail is more forgiving on the body and allows walking, but road is more familiar to those coming from marathons.
What’s the average finish time for a 50K trail race?
Anywhere between 5 and 8+ hours, depending on terrain, weather, and individual pacing.
What shoes should I wear for a trail sub-ultra?Trail running shoes with grip, protection, and comfort. Cushion level depends on personal preference and race terrain.
Can I listen to music during a sub-ultra?
Most races allow it on road; on trails, it’s often discouraged or banned for safety. Always check the rules.
Will I need a support crew?
No. Most sub-ultras are solo efforts with aid stations. Crews are optional and rarely needed unless specified.
What happens if I can’t finish?
Sub-ultras often have aid stations or shuttle points for dropouts. Train well, pace smart, and don’t fear failure — finishing isn’t everything.
About the Author Lost Pace is an ultramarathon runner, shoe-tester and the founder of umit.net. Based year-round in Türkiye’s rugged Kaçkar Mountains, he has logged 10,000 + km of technical trail running and completed multiple 50 K–100 K ultras.
Blending mountain grit with data, Lost analyses power (CP 300 W), HRV and nutrition to craft evidence-backed training plans. He has co-written 260 + long-form guides on footwear science, recovery and endurance nutrition, and is a regular beta-tester of AI-driven coaching tools.
When he isn’t chasing PRs or testing midsoles, you’ll find him sharing peer-reviewed research in plain English to help runners train smarter, stay healthier and finish stronger.
Ultrarunner · Data geek · Vegan athlete
