What is an ultra marathon (and how do you prepare for one)?

What is an ultra marathon? Any running race longer than a marathon's 26.2 miles (42.195 km). That's the whole definition. A 50K that's five miles longer than a marathon is an ultra. So is a 240-mile loop through the Utah desert that takes most of a week. The word covers a lot of ground, in both senses.

Ultras are mostly slower, longer and more about eating than people expect. The training builds on marathon training rather than replacing it, which is good news if you've already done one. And if you lift, you don't have to give that up either: a Runna alternative that includes lifting can schedule both around your long days. Here's what ultras are, who runs them, and how to prepare for one.

What is an ultra marathon, exactly?

The Ultra Sports Science Foundation's position statement defines ultramarathon running as any running event over marathon distance, conducted on any terrain and surface (Scheer et al., 2020). Road, trail, track, mountain, desert: if it's longer than 42.195 km, it counts.

Most people come to ultras from the marathon, and that's the sensible order. A marathon build teaches you long runs, easy pacing, fueling and tapering, which is most of what an ultra asks for, just stretched. If you haven't done that yet, a marathon plan with strength is the better first project, and the full breakdown of a build is in how to train to run a marathon.

Common ultra marathon distances

Ultras also come in other formats:

• ›Timed events: run as far as you can in 6, 12 or 24 hours, usually on a short loop.
• ›Stage races: several days of running, with a set distance each day.
• ›Backyard-style loops: a fixed loop every hour until one runner is left.

The oldest ultra

The Comrades Marathon in South Africa has been run since 1921 and is described in the research as the oldest ultramarathon in the world (Nikolaidis et al., 2021). Despite the name, it's well beyond marathon distance.

The Moab ultra marathon

When people search "Moab ultra marathon", they usually mean the Moab 240, a single-loop trail race around Moab, Utah. The organizer lists the course at 241.8 miles with a 112-hour cutoff, through desert, canyons, slick rock and two mountain ranges near Canyonlands and Arches National Parks. It is not, to be clear, a sensible first ultra.

The Michelob Ultra El Paso Marathon is not an ultra

A lot of people search "Michelob Ultra marathon El Paso" expecting an ultra. The "Ultra" is the beer sponsor. The Michelob Ultra El Paso Marathon is a standard 26.2-mile marathon, held alongside a half marathon and a 5K. Perfectly good race. Not an ultra.

Who are ultra marathon runners?

Mostly people who ran marathons first and wanted something longer, slower or more scenic. Research on ultra marathon runners gives a few useful facts:

• ›Injuries are common. In a survey of 1,212 active ultramarathon runners, 64.6% reported an exercise-related injury in the previous year that cost them training days, and the younger, less experienced runners were the ones most at risk (Hoffman and Krishnan, 2014).
• ›They aren't unhealthy as a group. The same study concluded that, compared with the general population, ultramarathon runners appeared healthier and reported fewer missed work or school days (Hoffman and Krishnan, 2014).

The practical takeaway from that injury finding: experience matters. Build up over years, not weeks.

How to prepare for an ultra marathon

The structure is the same as a marathon: base, build, peak, taper. What changes is how much time each part needs and what the long days look like.

1. Have a marathon-level base first

Before an ultra build, you should be comfortable running four or five times a week and handling long runs of 15 miles or more. Having run your first marathon is the cleanest way to know you're there. If you haven't, start with that. Knowing how long does it take to train for a marathon from your starting point tells you how far away an ultra really is.

2. Train time on feet, not just miles

In a 50-miler, the hours matter more than the distance. Build the long run by time: three hours, then four, then five, mostly at an easy, conversational effort. Walking breaks are allowed. Walking the climbs is a skill.

3. Use back-to-back long runs

A common ultra session is a long run on Saturday and another medium-long run on Sunday. The second day teaches you to run on tired legs without the injury risk of a single enormous run. Many 50K and 50-mile plans use them in the peak weeks.

4. Train for the terrain

If your race has climbing, train on hills. If it's on technical trail, run on technical trail. If you'll be power-hiking steep grades, practice power-hiking steep grades. Road marathon fitness carries over, but not completely.

5. Run by effort

Pace is close to meaningless on a mountain. Most ultra runners train and race by effort or heart rate, and the same principles that set marathon heart rate targets apply: easy most of the time, conservative early in the race.

6. Keep lifting

The same rules as a marathon build: one or two sessions a week, heavy-ish and low volume, kept away from your long days. A good marathon strength workout transfers almost directly. Add step-ups and single-leg work if your race has a lot of climbing.

A sample week in a 50K build

Mid-build, for someone who also lifts:

The weekend is the hard part of the week. Treat it that way: nothing heavy on Friday, and nothing heavy on Monday's legs either.

Fueling for an ultra marathon

In an ultra, eating is not a side issue. It's half the race.

The International Society of Sports Nutrition's position stand on single-stage ultra-marathons recommends (Tiller et al., 2019):

• ›During racing: 150 to 400 kcal per hour, including 30 to 50 g of carbohydrate and 5 to 10 g of protein, from a variety of calorie-dense foods.
• ›Fluids: 450 to 750 mL per hour, with sodium that may need to be higher than most commercial drinks provide.
• ›Gut training: practicing eating while running to reduce stomach problems on race day.
• ›In training: a moderate-to-high carbohydrate diet of around 5 to 8 g/kg per day, and protein of about 1.6 g/kg per day.

That carbohydrate rate is lower than the up to 90 g per hour some marathon guidance uses for efforts beyond about 2.5 to 3 hours (Thomas, Erdman and Burke, 2016), which reflects how different a 12-hour effort is from a 4-hour one. Either way, the number you can actually tolerate is something you find in training.

Expect the scale to move during the build as your fuel stores and appetite go up. The reasons are the same as why you gain weight during marathon training: mostly fuel and water.

This is general guidance. If you have a medical condition, talk to a doctor or registered dietitian before changing how you eat.

Race week and race day

• ›Taper for two to three weeks, like a marathon. More for very long races.
• ›Nothing new. Not shoes, not packs, not food.
• ›A short, easy jog the day before is fine, the same idea as a shakeout run before marathon day.
• ›Start embarrassingly slow. In an ultra, the runners who passed you at mile 5 are often the ones you pass at mile 40.
• ›Eat early and on a schedule. Set a timer if you need to.

Can you run an ultra without training?

No. Trying to run a marathon with no training is already a bad idea. Adding more miles to a bad idea doesn't improve it. Ultras reward years of consistency more than any single build.

Ultra marathon documentaries

If you want to see what you're getting into, ultra marathon documentaries are a popular rabbit hole. One of the best known is The Barkley Marathons: The Race That Eats Its Young, about the Barkley Marathons and the people who try to finish it. Watch it for motivation. Don't watch it for training advice.

How exrsz handles ultra prep

exrsz builds a periodized plan from your goal, event date, schedule, level and equipment, with running and lifting balanced in one plan, so your strength work stays away from the long weekend days. It adapts each week to how your training actually went and reshuffles missed sessions so the build still lands on race day.

FAQ

What is an ultra marathon?

Any running race longer than a marathon (42.195 km, or 26.2 miles), on any terrain (Scheer et al., 2020). Common distances are 50K, 50 miles, 100K and 100 miles.

How long is the shortest ultra marathon?

There's no fixed minimum beyond being longer than 26.2 miles, but the 50K (about 31 miles) is the most common entry-level ultra distance.

How do you prepare for an ultra marathon?

Build a marathon-level base first, then train time on feet with longer long runs, back-to-back weekend runs, terrain-specific work and lots of fueling practice. Keep one or two strength sessions a week and taper for two to three weeks.

What should I eat during an ultra marathon?

The ISSN position stand suggests 150 to 400 kcal per hour, including 30 to 50 g of carbohydrate and 5 to 10 g of protein, plus 450 to 750 mL of fluid per hour (Tiller et al., 2019). Practice it in training first.

Is the Michelob Ultra El Paso Marathon an ultra marathon?

No. It's a standard 26.2-mile marathon, held with a half marathon and 5K (KVIA, 2026). "Ultra" refers to the sponsor.