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18-Week 50K Training Plan For First-Time Ultrarunners

The ultimate 18-week ultramarathon training plan for beginners.

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Committing to a journey where you will embark by foot farther than you have ever traveled before is equal parts exciting and scary. After pulling the trigger and signing up for an ultramarathon, a flood of emotions will begin. You know you have to put in the work, but the hows and whys that often fill your mind before the start of this journey trigger those feelings of anxiety. These emotions are normal and—ironically enough—often sought out by folks after completing their first ultramarathon, when they sign up to tackle an even longer ultra. Embracing this mental and physical challenge can make the journey as exciting as the event itself, but it’s certainly no reason to ignore the experience of others. For that, I hope to provide some useful experiences to prepare you for your first ultramarathon.

Treat recovery as a training tool. The first strategy with newcomers is to ditch the “go big or go home” mentality. It’s fine to go big when the time is right, but ignoring the necessities of rest and recovery is a mistake. Big days are fine when met with proper recovery, but reaching too far or hard day in and day out is unsustainable. Being realistic is key in generating just enough stress to elicit a response, but not overreach so far that you struggle to recover, or get injured.

Stress can be both good and bad. The right amount causes us to get stronger and more resilient, but too much burns us out. Monitoring stress from all areas of life is crucial in choosing when to set up hard or long training days. When planning your training, avoid placing your most rigorous or time-consuming workouts on your most stressful days in other areas of life. It’s mindful to refrain from viewing your training plan as set in stone. Be flexible enough that you can adjust to life’s stress both inside and out of your training plan.

Consistency is key. Although some training methodologies may differ, one thing that appears in all is consistency. Giving yourself a consistent routine to build off of will make you a strong and confident runner.

Build a strong aerobic base. A common mistake in training is trying to put fast-paced work in place with no foundation. Ultramarathon running is highly aerobic. Starting out by building a strong aerobic base will provide a foundation for the race and course-specific workouts that will make up some of the key training blocks later in the training program. Keeping a close eye on your level of perceived exertion and heart rate is a great way to keep you honest during the aerobic base–building phase.

Specificity is king. The diverse range of course environments available means that adapting to the proper terrain and weather is a big factor. I encourage newcomers to the sport to pick an event that offers terrain and weather that are easily accessible. This will allow you to maximize the way your body develops for the event. Key factors to look into include surface type, elevation gain and loss, weather trends during the time frame of the event and technicality of the terrain.

Ultrarunning is an incredible journey that continually offers up new challenging opportunities as you learn what you are capable of throughout your growth in the sport. Read on for an 18-week training plan that will help prepare you for a 50K ultramarathon on a hilly trail course, and see the box on page 48 for a few gear tips to consider.

Base pace: To determine your base pace using heart rate, it is approximately 180 minus your age, +/- 5 beats per minute (bpm).

Time: The planned time of each workout is in the format of 00(hours):00(minutes):00(seconds).

Gear List


Have at least two options and consider terrain when selecting your shoes. Example: When doing a trail event, I start out in the Altra Superior, but I bring the Altra Timp for backup. Most events will have drop bag options where you can stash your backup pair, and then race organizers will deliver what you leave to the finish line.


Thickness is a personal preference in most cases, but like shoes, always bring a backup for your drop bag. Finding a pair that keeps your feet from staying wet or rubbing is important in avoiding blisters. Example: When doing a trail event I start out in Drymax Run Lite Mesh Crew, but include a pair of Drymax Run Lite Mesh no show (it’s easier to put on the lower-profile and flexible pairs when transitioning mid-race).


The time it takes to complete an ultramarathon can often mean varied temperatures or even rain. I always bring a long-sleeve layer that is easy to stow and at least semi-water-resistant, e.g., the Altra Performance Half Zip.

The Training Plan

Snapshots of the 18-week training plan are provided below. To access and save the full training plan PDFs, find the download link beneath each snapshot.

Click here to download the PDF for weeks 1-3.

Click here to download the PDF for weeks 4-8.

Click here to download the PDF for weeks 9-13.

Click here to download the PDF for weeks 14-18.

Zach Bitter is an ultra-endurance athlete for Altra Footwear and Xendurance. He has been training for—and racing—ultras since 2010, having completed more than 40 ultras ranging from road to track and trail to mountain. He has competed at three World 100K Championship races, won three national championships, and holds world and American records. As a coach for Sharman Ultra, he has trained a diverse set of athletes from around the world.


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