An ultrarunner is anyone who races distances longer than a standard marathon, which is 26.2 miles. That means the shortest ultra distance, 50 kilometers (31 miles), is only about 5 miles beyond a marathon, while the longest events stretch to 100 miles or more. The term covers a wide spectrum of athletes, from weekend warriors finishing their first 50k to elite competitors racing through mountain ranges for days.
How Far Ultrarunners Actually Race
The most common ultra distances are 50 kilometers (31 miles), 50 miles, 100 kilometers (62 miles), and 100 miles. Certified races go all the way up to 3,100 miles, though those extreme events attract a tiny niche. Most people entering the sport start at the 50k distance, which feels like a natural next step after completing a marathon.
Not all ultras are measured by distance. Timed events challenge runners to cover as much ground as possible within a set window: 6 hours, 12 hours, 24 hours, 48 hours, or even 6 days. These races typically take place on short loops, so runners can access aid and supplies on every lap. The appeal is that there’s no required distance to “finish.” You run what you can, and whatever you accumulate counts.
Trail ultras, which take place on dirt paths through mountains and forests, are the most popular format. But road ultras, track ultras, and point-to-point races across deserts or between cities all exist. Mountain ultras often involve tens of thousands of feet of elevation gain, turning the event into something closer to hiking at high intensity than flat-ground running.
Who Runs Ultramarathons
The typical ultrarunner is older than you might expect. The average age across timed ultra events has settled around 45 to 46 years old, and that number has been climbing for decades. In the late 1980s, the average was closer to 40. Unlike sports that favor youth, ultra distances reward patience, experience, and the willingness to suffer steadily over many hours. Runners in their 40s and 50s routinely outperform younger competitors.
Women currently make up about one-third of ultramarathon finishers in North America, a share that rose from under 25% in 2000 and has held steady near 34% since 2018. The sport is growing fast overall. North America alone is on pace for more than 150,000 ultramarathon finishes in 2025, climbing steadily every year since 2000 with the only dip coming during the 2020 pandemic shutdown. In 2024, nearly 42,000 of those finishes (about 29%) came from first-timers.
What Ultra Distance Running Does to the Body
Running for 10, 20, or 30-plus hours pushes the body into territory that shorter races never touch. The energy demand is enormous, and no runner can eat enough during a race to keep up with what they’re burning. This caloric deficit causes the body to break down both fat stores and muscle tissue for fuel. Runners commonly lose several pounds during a single event, and that weight loss comes from fat and lean muscle alike.
Muscle damage during an ultra is severe by any clinical standard. A blood marker called creatine kinase, which indicates muscle breakdown, can spike to levels 100 to 500 times above normal. At the Western States 100-Mile Endurance Run, two-thirds of finishers showed dramatically elevated muscle damage markers, and 6% had levels that would trigger alarm bells in a hospital setting for someone who hadn’t just run 100 miles. The heart also shows temporary stress. One study found that a cardiac stress marker increased by 900% after a 43-kilometer mountain ultra. These changes are generally reversible, with most blood markers returning to baseline within about five days of recovery.
The body’s fuel strategy shifts dramatically during an ultra. As stored carbohydrates run low over many hours, the body increasingly relies on fat for energy. This metabolic shift is one reason ultrarunners often train with higher fat intake and practice fueling strategies during long training runs, so the body becomes more efficient at burning fat while preserving limited carbohydrate stores.
The Psychology of Going That Far
Ultrarunners don’t simply have more willpower than the average person. Research on athletes competing in the Marathon des Sables, a grueling multi-stage desert ultra, found a distinct personality profile compared to the general population. These runners scored significantly higher on traits like openness to experience, excitement seeking, and comfort with strong emotions. They also scored lower on anxiety and vulnerability to stress.
Interestingly, the study found that ultrarunners didn’t score higher on self-confidence than non-athletes, despite self-confidence being considered the core component of mental toughness in most sports psychology models. What set them apart was not an unshakeable belief in themselves but rather a lower baseline of fear and a higher tolerance for the unknown. They were also more impulsive and less deliberate in their decision-making, traits that may help explain why someone signs up for a 100-mile race in the first place.
During races, ultrarunners use a mix of mental strategies. Some focus intently on body signals like breathing, foot strike, and effort level. Others deliberately distract themselves, letting their minds wander to music, conversation, or daydreaming. Which approach works better is still debated, and most experienced ultrarunners switch between the two depending on how they feel at different stages of the race.
How Ultrarunners Fuel During a Race
Eating and drinking during an ultra is not optional. It’s a core skill that can make or break a race. The International Society of Sports Nutrition recommends ultrarunners consume 150 to 400 calories per hour, with 30 to 50 grams of carbohydrates and 5 to 10 grams of protein per hour. For races up to 50 miles, the lower end of that range is usually sufficient. For 100-mile races, runners need to push closer to 200 to 400 calories per hour because the accumulated caloric deficit becomes harder to tolerate.
Faster 100-mile finishers tend to eat more carbohydrates per hour (around 44 grams) compared to slower finishers (around 31 grams), suggesting that the ability to eat well while running hard is a performance advantage, not just a survival strategy. Real-world race food looks nothing like a sports nutrition ad. Ultrarunners eat potato chips, peanut butter sandwiches, broth, gummy candy, boiled potatoes, and whatever else their stomach can handle after 15 hours of running.
Hydration targets fall between 450 and 750 milliliters per hour, roughly a standard water bottle every one to two hours. Sodium replacement is critical. Runners need concentrations higher than what most commercial sports drinks provide, targeting 300 to 600 milligrams of sodium per hour to avoid hyponatremia, a dangerous condition where blood sodium levels drop too low from excessive water intake without enough electrolytes.
Training for Ultra Distances
Most amateur ultrarunners training for their first 50k or 50-mile race build up to 40 to 50 miles per week. Training for 100-mile races pushes that to 50 to 70 miles per week, depending on experience level. Beyond the amateur ranks, training expands to include multiple runs per day, significant vertical gain on trails, and occasional multi-day efforts that simulate the fatigue of race conditions.
The emphasis shifts compared to marathon training. Speed work becomes less important, and long, slow efforts on terrain similar to the race course take priority. Back-to-back long runs on consecutive days are a staple of ultra training plans because they teach the body to perform on tired legs, which is essentially the entire second half of any ultra.
Gear That Ultrarunners Carry
Mountain and trail ultras commonly require runners to carry mandatory gear, verified at check-in before the race starts. A typical mandatory list includes full waterproof clothing (jacket and pants), a first aid kit, a map and compass for self-navigation, a headlamp with at least 400 lumens and spare batteries, an emergency bivvy bag for retaining body heat if something goes wrong, a whistle, and a hydration system capable of carrying enough fluid between aid stations.
Runners choose between handheld flasks, vest-mounted soft bottles, or hydration bladder reservoirs worn on the back. Most ultrarunners prefer running vests that distribute weight evenly and include pockets for food, a phone, and extra layers. For races that push through the night, carrying a backup headlamp is common practice since being stranded on a mountain trail in the dark with a dead light is a genuine safety risk, not just an inconvenience.