A Female Runner On A Trail Above A Deep Valley With Flowers Lining The Trail

How to Transition from Triathlon to Ultrarunning

BY Maria Simone

More and more triathletes are making the jump to ultrarunning. Here’s what to expect and how to prepare for your first ultra.

You’ve pushed your body through 70.3 or 140.6. Multiple times. Now, you’re wondering what’s next.

It’s an inevitable progression, right? We always want to push our limits: faster or farther, or both.

Maybe your next thing is an ultramarathon. You won’t be alone in making that transition.

According to a 2021 study cited in The Guardian, there has been “a 345% increase in ultramarathon participation globally over the past 10 years.”

The most popular distance is 50K, but events go to 100 miles and beyond. Some races feature an allotted time frame, such as six, 12 or 24 hours. For the super hardy, a few races traverse 200 miles and at least one race—Infinitus—offers you an 888-kilometer challenge.

In this article, I’ll cover some things to consider as you transition from triathlon to ultra-running.


Some ultramarathons are on the road, but most are on trails, which makes them unique. I love the unpredictability and changing nature of the trails! However, trails are more challenging to navigate than smooth roads of triathlon.

To help select a course that is appropriate for you, UltraRunning.com categorizes races by elevation and surface. An elevation rating of 1 or 2 means the course features 50 feet or less per mile of gain. A surface rating of 1 or 2 means the course is on-road or mostly groomed trails.

Conversely, if you select a course rated as 4 or 5 on either of those measures, you will be racing on some of the toughest courses, with climbing beyond 200-250 feet per mile on average and surfaces that feature rocks, boulders, roots, sand or mud—or all of the above and more!

The nature of the course determines how you should structure your training in terms of volume, intensity and specificity.

Training Volume

Your weekly volume will likely be less than it was for IRONMAN training. However, the running volume will be more. Part of this run volume increase comes from running more on trails, which are slower-going than roads. A 22-mile run on trails can take an hour longer (or more) than one on the road.

For a 50K to 50-mile race, the weekly run volume may range from six to eight hours a week or 40 to 70 miles per week. For races beyond 50 miles, that volume can jump to 10+ hours and 80+ miles per week. But, a warning: more is not always better!

How much you run depends on your previous max run volume, recovery rates, and ability to absorb the load. Gradual adaptation is critical to avoiding injury, burn out and overtraining.

In addition to running, we recommend that you continue to bike and swim once to twice per week, depending on your available time. This cross-training will keep you in the game should you decide to transition back to triathlon after your ultra!

Training Intensity

Intensity in ultra-running, especially as the run volume gets longer, is different from triathlon training. You won’t spend much time at the track; however, you still want to get the heart pumping.

We recommend two primary ways to add intensity to runs:

  • Tempo effort
  • Strength sessions

Tempo runs include efforts at 90 to 95 percent of LTHR or 80 to 85 percent of max effort, on road or smooth trail.

Options for strength-focused runs include:

  • Traditional hill repeats, running up the hill at a tempo or hard effort, recovery on the descents. (If you don’t live in a hilly area, see our tips for simulating hill training.)
  • Downhill Repeats (“fast downs”). This workout is described in the link above.
  • Power hiking steep grades with a weighted vest. Recovery easy without the vest.
  • Pulling a tire. Yes, my neighbors think I’m crazy when I run around town pulling a tire. Yours will too—but that’s part of the fun. (See trailtoes.com for a special harness you can use for the tire.)

For threshold or VO2 max work, hop on your bike or dip in the pool for some high-end intervals. Work hard without the injury risk that comes with running speed work.

Training Specificity

Run on terrain similar to your goal race in terms of elevation (average gain/loss per mile) and surface (smooth trail vs. roots/rocks and other things that go bump in the night). Not every run needs to be on race-specific terrain, but your long run should be.

Pay attention to vertical gain if you are doing a hilly course. For example, if the ultra you’ve selected averages 75 feet of gain and loss per mile, identify similar training routes. Don’t discount the descent training! The descents can be technical and punishing on the muscles. Prepare for them!

Examine the elevation profile for your race. Are there extended climbs and descents, or does the course roll? Is the first half different from the second half? Again, mimic these conditions in training routes.

Putting it together

Here’s a sample of how a week may be organized by putting together the principles of specificity, volume and intensity.

Rest Day or active recovery day (easy swim is perfect!)Key Run: Strength and/or intensity run

Strength training (weights, and/or functional strength)

Intensity bike or swim

Easy run (short)

Base miles – easy to steady effort (60-85% of LTHR).

Strength training (weights, and/or functional strength)

Easy active recovery day (swim or bike)Key Run: Long Run, race-specific terrain, easy to steady effort.Easy, short run

Recovery bike or swim

A few caveats:

  • This outline will not work for all athletes. It’s an example only. Consult the advice of a coach to determine what will work for your circumstances.
  • The long run will vary based on proximity to and length of the race. For a 50K, your peak long run may be in the 20 to 24-mile range. For a 50-miler, your peak long run may be 26 to 31 miles.
  • The duration of the base and easy runs will depend on your training history, and race distance.

Fueling and hydration

Fueling and hydration for an ultra are not much different from what you might normally do for a marathon. However, because the intensity is lower, some ultra-runners prefer to eat more whole food. The longer the race, the more likely you’ll want to chew on something substantial.

Take in calories in smaller blocks, and avoid eating a big block of calories all at once. If you are planning to eat 200 calories per hour, eat that in 100-calorie segments every 30 minutes or 60-calorie bites every 20 minutes.

Be sure to practice your fueling and hydration every long run to ensure it works! Take note of how the conditions of the day (hot, cold, moderate) impact calorie and fluid needs. Be prepared to make adaptations.

Race Day Execution

Proper pacing makes the difference between finishing strong and crawling in. But what “counts” for pacing?

Given the changing terrain, sticking to consistent minutes per mile is not recommended in trail running. Instead, use a combination of heart rate and rate of perceived exertion (RPE). The effort should feel easier than you think it needs to be in the opening half.

When the course goes up (and up), you can plan on changing from a run to a power hike, and return to running as soon as the trail or road flattens or descends. If you can’t see the top of the hill, hike it. Use your heart rate as a check: if you notice your heart rate climbing too high, hike.

Aid stations are typically about four to six miles apart. Consider what you will need to go this distance without aid. For example, will you use hand-held water bottles or a hydration vest to carry your fluids and calories?

Unlike triathlon, ultrarunning allows outside assistance from your crew at designated handler stations. Have a plan for your crew. Make sure they understand what is expected. We use a toolbox (from a hardware store) that makes it easy for our crew to bring supplies. It includes:

  • electrolytes
  • fuel sources (gels, powders, bars, etc.)
  • socks
  • lube and foot care items

Running for many hours will require you to problem-solve. Tune in to the signals your body is giving you, and respond. On a long day of running, you have plenty of opportunities to fix problems. Assess what you need and adapt.

If you experience GI distress, slow down. Eat and drink something. Take some Tums. Wait 15 minutes. It could be a brand new day.

If it is hot, take the time to cool off. We ask our crew to bring neckerchiefs with sewn-in pockets full of ice on hot days. Aaaahhhhh. The ice can last for many miles!

If you feel your sock bunching up in the first five miles, stop to fix it! At 45 miles, that same “bunch” will feel like a boulder.

You get the point. Stuff happens. Deal with it. Otherwise, it has a way of piling up by mile 50 or beyond.

With careful problem solving, I’ve seen (and experienced firsthand) races turn around that seemed past the point of no return. Don’t stop believing!

An ultramarathon will push you past what you think your limits might be. Tough conditions require a tough mind. Push yourself to those limits in training, and you will be prepared for whatever race day brings.

Web Ultramarathon Training Guide

The Complete Ultramarathon Training Guide

Training Guide

In this guide you'll find tips from top trail running coaches on the training, logistics, and mental tricks you'll need to complete a successful ultramarathon.

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About Maria Simone

Maria Simone is the owner and head coach of No Limits Endurance Coaching. She manages a staff of eight coaches and a team of 140 athletes. She is a USA Triathlon Level 2 long course, USA Cycling Level 2, and US Masters Swimming Level 1 certified coach. She was the 2021 Coach of the Year, awarded by Outspoken Women in Triathlon.

Maria offers mentoring for newer and intermediate coaches to support growth in coaching and business development. She takes a holistic approach to training that cultivates her athlete’s goals, physical ability and mental strength while managing a life-work-training balance. She is an active endurance athlete, enjoying long weekends in the pain cave, races with lots of hills, and hard runs through meandering singletrack trails with her husband John and her two dogs, Pace and Kea.

Visit Maria Simone's Coach Profile

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