Choosing your First Ultra
Trail Notes | Female Athlete Racing
start where your body actually is
Choosing Your
First Ultra.
The most ambitious thing you can do as a new ultrarunner is not to sign up for the longest race you can imagine. It is to pick the distance your body is ready to learn from.
When you are new to trail ultras, the first question is rarely "can I finish this." It is usually "how far, and how soon." The honest answer depends less on how much you want it and more on what your body has had time to build.
In Australia the ladder many of us climb is clear. A shorter trail race of roughly 20 to 30 kilometres, then the 50km, then the 100km. The big mountain and coastal events we love, from Ultra-Trail Australia to Surf Coast Century, Buffalo Stampede, Tarawera across the water and Kosciuszko, are largely built around those distances. A true 100-miler is less common here. It exists at a small number of events, but for many of us the 100km is the realistic summit of the sport, not the 100 miles.
For our purposes, a new ultrarunner is someone with 1 to 2 years or fewer of endurance training and few or no ultra finishes. If you arrive with a marathon background, or strong cross-sport fitness from cycling, triathlon, swimming or hiking, you may progress faster. What matters is your aerobic base and your time on feet, not just your running history.
The right first distance is the one that builds your skills without exposing you to the failure points you cannot yet survive.
Gut tolerance, deep musculoskeletal resilience and pacing at long duration all take time. Choosing well means choosing the distance where those systems are ready.
Trail Note · 01
The 50K is home base
A 50K is a good first ultra for many of us once we have a base. Do not let anyone tell you it is a short day. On technical Australian trails, with real vert underfoot, a mid or back of pack finish can take anywhere from 5 to 10 hours. That is a long time on your feet, which is exactly why it teaches you so much, and it is still short enough to complete without systems that take years to develop. If you have been running consistently for 12 months or more, you can usually prepare inside a 16 to 24 week block. Starting from a lower base, give yourself 6 to 12 months of patient base building first, and a shorter trail race of 20 to 30 kilometres is a perfect stepping stone along the way.
This tier suits a real life. Demanding job, family, around 6 to 8 hours a week for training and recovery, 1 to 3 events in a year. It is not the soft option. It is the distance that lets you develop everything you need for longer races without the failure points that sink rushed first attempts at the big stuff.
Get the 50K right and the 100km becomes a logical next step, not a gamble.
Trail Note · 02
The 100km asks for adaptations, not just ambition
The 100km, 8 to 16 hours of racing, is a realistic goal once the key adaptations are tracking correctly. With a solid marathon background and a year or more of trail running, 12 to 18 months of ultra training is realistic. Starting from scratch, expect 18 to 24 months before the musculoskeletal and gut adaptations are ready.
The honest reason for the timeline is simple. The tendons, bone density and gut tolerance you need at this distance take many months of consistent load to develop, and for most new ultrarunners that means well over a year. You cannot rush them with bigger training weeks. Trying does not accelerate the adaptation. It accelerates the injury.
Trail Note · 03
What about the 100-miler?
A handful of Australian events offer a true 100 miles, and they are wonderful, hard days. For many of us, though, the 100km is the long-distance goal that matters, and there is nothing junior about it. If 100 miles is calling you, treat it as a multi-year project that sits well beyond your first ultra. It needs gut tolerance for a full day on the move, deep structural resilience, sleep deprivation management and pacing at durations you have never met in training.
The question is never whether you could finish one in year one. The question is whether the systems you need are ready. Finishing a 50K and a 100km first means you arrive with evidence, not hope.
Her Trails coaching cue
Pick the distance where your gut, your bones and your pacing have something to stand on. Ambition is the easy part. Adaptation is the part that decides your race.
Trail Note · 04
A simple way to find your starting point
Find the line that sounds most like you, then hold the timeline honestly.
The distance decision check
New to endurance sport, 6 to 8 hours a week, high life stress. Build base first. First distance a shorter trail race, then 50K. Timeline 12 to 18 months.
Marathon background, consistent runner, 8 to 10 hours a week. Ready for a specific block. First distance 50K. Timeline 6 to 12 months.
Strong endurance base from cycling or triathlon, 10 to 12 hours a week. Needs trail-specific adaptation. First distance 50K, then 100km. Timeline 12 to 18 months to the 50K, with the 100km to follow.
Completed 2 or more 50K events, stable health markers. Ready for a 100km build. Timeline 18 to 24 months from your ultra start. A 100-miler, if you want one, comes later still.
Any of us with menstrual disruption, low ferritin or bone symptoms. Address health first, with your doctor. Hold the distance goal until markers resolve. (Cycle changes can also relate to hormonal contraception or perimenopause, which is another reason to get them checked rather than assume.)
Notice the last line. No distance goal sits above your health. If your cycle, your iron or your bones are sending signals, that is the work that comes first, whatever the race calendar says.
You are not choosing between brave and cautious. You are choosing the distance that lets you keep racing for years.
Base. Consistency. Time on feet. Gut tolerance. Bone resilience. Then distance.
start where you are, not where you wish you were
Written by the Her Trails coaching team
Trail Notes are evidence-informed coaching journals written for women who train, race and run on trails. Made to be absorbed in 10 minutes and remembered for a season.
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