How to Pick Your First Ultra Without Wrecking the Next Six Months

To pick your first ultramarathon, choose a 50K (31 miles) on runnable terrain with generous cutoffs and frequent aid stations, set 16-24 weeks out, after you've already run a marathon or long runs of around 30 km (18.6 miles). Then block out three to four weeks of recovery afterwards before you plan anything else. Your first ultra should be the easiest one you can find that still excites you.

Key takeaways

• A 50K is the best first ultra for most runners: it's only 8 km (5 miles) past the marathon, so you can focus on the new skills of fueling, hiking and pacing.
• Read the course numbers, not the photos: elevation gain per kilometre, cutoff pace and aid station spacing tell you how hard it really is.
• In the largest survey of ultrarunners, younger and less experienced runners were the most likely to get injured. Build experience before distance.
• Plan the race and the month after it. Recovery is part of the event.

Are you actually ready?

Ultra readiness is less about talent and more about durability. Before signing up, you should be able to say yes to most of these:

• You've been running consistently for at least a year.
• You've completed a marathon, or long runs of 28-32 km (17-20 miles), without breaking down.
• You can handle 50-65 km (31-40 miles) per week for several weeks without niggles.
• You've practised eating during runs longer than 90 minutes.

The best data on ultrarunner health comes from the ULTRA Study by Martin Hoffman and Eswar Krishnan. Their 2014 baseline paper in PLOS ONE surveyed 1,212 active ultramarathon runners. Most (64.6%) had lost training days to an exercise-related injury in the previous year. The knee was the most common injury site, and the annual stress-fracture rate was 5.5%, higher in women. Crucially, injured runners tended to be younger and less experienced.

The lesson: years in the sport protect you. If you're new to running, a first ultra can wait a season.

Choose the right distance

Ultras come in a few standard flavours:

• 50K (31 miles): the classic entry point. Most first-timers finish in 5-9 hours.
• 50 miles (80 km): a big jump. Expect 9-15 hours and often some running in the dark.
• 100K (62 miles): usually a full day or more, with serious fueling and foot-care demands.
• 100 miles (161 km): a different sport. Save it until you've finished several shorter ultras.
• Timed events (6 or 12 hours): you run laps of a short loop and stop whenever you like. These are underrated first ultras because aid is never far away and there is no cutoff to fear.

Start with a 50K or a 6-hour timed event. You'll learn more from finishing well than from surviving something too big.

Read the course like a coach

Race photos sell mountains and sunsets. The numbers tell you what race day will feel like.

Elevation gain per kilometre

Divide total climbing by distance:

• Under 20 m/km (about 100 ft/mile): largely runnable. Ideal for a first ultra.
• 20-40 m/km (100-210 ft/mile): hilly. Expect plenty of power hiking.
• Over 50 m/km (265 ft/mile): mountain racing. Times can double compared with road.

A 50K with 1,000 m (3,280 ft) of climbing works out to 20 m/km, which is a moderate, friendly first ultra.

Cutoffs

Work out the pace you'd need to make the final cutoff. A 50K with a 9-hour limit needs 10:48/km (17:23/mile) on average, including aid station stops. If that pace makes you nervous on that terrain, pick a race with a more generous limit.

Aid stations and support

For a first ultra, look for aid every 8-12 km (5-7.5 miles) and the option of drop bags. Long unsupported stretches mean carrying more water, food and gear.

Terrain, season and logistics

Smooth forest trails are a far gentler introduction than rocky, technical singletrack. Check the typical temperature on race day, whether you'll need a headlamp, any mandatory gear list, and how far you'd have to travel. A local race you can preview in training is often the smartest choice.

Time it so you don't wreck the next six months

This is where most runners go wrong. They pick a race that excites them, then discover it lands three weeks before their goal marathon, or right in the middle of their busiest work season.

Build backwards from race day

• Build phase (the first 14-22 weeks): build volume and long runs gradually, by no more than about 10% per week on average, with a lighter week every third or fourth week.
• Final 2 weeks: taper volume by 30-50% while keeping some short, faster running.
• Race day.
• The 3-4 weeks after: recovery, not new goals.

Respect the recovery

Running far causes significant muscle damage, and studies of ultra finishers show that blood markers of muscle damage can stay raised for days afterwards. Feeling fine on day three doesn't mean your tissues are ready for intervals.

A sensible return after a first 50K:

• Week 1: rest, walking, gentle mobility.
• Week 2: two or three easy 20-30 minute runs if nothing hurts.
• Week 3: about 50-60% of your usual volume, all easy.
• Week 4: around 75% of normal, with a few strides. Return to workouts from week 4-6 if you feel good.

Avoid the stacking trap

Don't schedule your first ultra within about 8-12 weeks before a goal marathon or other key race. Pick one "A" race per half-year and let the ultra be it.

Train for the race you picked

Long runs and back-to-backs

Your longest single run might be 30-35 km (18.6-21.7 miles) or 4-5 hours, whichever comes first. Pair it with a shorter run the next day, for example 25 km on Saturday and 15 km on Sunday, to practise running on tired legs without the injury risk of one enormous run.

Easy pace, hiking and terrain

Most ultra training should be easy, around 6:30-7:30/km (10:28-12:04/mile) for many recreational runners, or slower on trails. Practise power hiking on every steep climb, because almost everyone hikes in ultras, including the winners.

Fuel like it's part of training

Plan to take in roughly 60-90 g of carbohydrate per hour during the race and practise it on every long run. Our guide to why ultrarunners eat so much sugar explains why, and if your stomach rebels, read about runner's gut.

Drink to thirst rather than forcing fluids. The 2015 international consensus statement on exercise-associated hyponatremia, led by Tamara Hew-Butler, identifies overdrinking as the main cause of dangerously low blood sodium in endurance events.

Sample peak week (50K, about 6 weeks out)

• Monday: rest.
• Tuesday: 50 minutes easy with 6 × 20-second strides.
• Wednesday: 60 minutes with 5 × 4 minutes of hill hiking or running uphill at a strong effort.
• Thursday: 45 minutes easy.
• Friday: rest or 30 minutes easy.
• Saturday: 30 km on race-like terrain, practising race fuel.
• Sunday: 15 km easy on tired legs.

Expect the mental side to matter, too. Our piece on suffering on purpose without burning out offers tools for the low patches every ultra brings.

Red flags: when to stop or see a doctor

• Pain that changes how you run, or localised bone pain that hurts to press, could be a stress fracture. Stop and see a sports doctor or physio.
• Very dark or cola-coloured urine after a race, especially with severe muscle pain or swelling, can signal rhabdomyolysis. Seek medical care urgently.
• Confusion, severe headache, nausea or vomiting during or after a long event can signal low blood sodium. Get medical help rather than drinking more water.

Find your first ultra on Runtra

Ready to choose? Browse every ultra on the calendar, explore trail races to build experience on dirt, or search for 50K races near you.

FAQ

Is a 50K a good first ultramarathon?

Yes. A 50K is only about 8 km (5 miles) longer than a marathon, so the jump in distance is manageable. Choose a runnable course with generous cutoffs and frequent aid stations, and it becomes the ideal place to learn fueling, hiking and pacing.

How long should I train for my first ultra?

Most runners need 16-24 weeks of focused training, assuming they already have a solid base and have run a marathon or similar long runs. Build gradually, include back-to-back long runs, and taper for the final two weeks.

Is it OK to walk during an ultramarathon?

Absolutely. Nearly everyone walks in ultras, especially on steep climbs, and power hiking is often as fast as running uphill while saving energy. Practise hiking in training so it feels natural on race day.

How long does it take to recover from a 50K?

Plan on three to four weeks before returning to normal training. Take the first week mostly off, rebuild with short easy runs in weeks two and three, and resume harder workouts around weeks four to six if nothing hurts.

How much should I eat during my first ultra?

Aim for roughly 60-90 g of carbohydrate per hour from gels, drinks, chews or real food, starting early in the race. Practise exactly what you'll use during long training runs. Drink to thirst rather than on a forced schedule.