Endurance-Based Workouts for Ultramarathon Training

The role of endurance-based workouts – long runs, easy runs, and recovery runs – in ultramarathon training.

By on November 1, 2022 | Comments

The long run: It’s the chance to spend hours on your favorite routes and do what sets us apart from most other runners — to run far. Elite marathoners seldom run more than 24 miles in one session, but ultrarunners typically run farther than that on a regular basis. There are three endurance-based workouts that can enhance your staying power over ultramarathon distances. Before diving into the specifics of the long run, let’s first discuss the two shorter, often overlooked, endurance-based workouts: easy runs and recovery runs.

Easy Runs

Easy runs maintain and maximize your aerobic fitness. Most runs within a given week fall into this category. They are shorter than 90 minutes and are done at an easy pace. Yet, many runners fail in their training by running these too fast. Though the pace should be steady, you should still be able to hold a relaxed conversation and maintain your heart rate below 75% of its maximum.

Easy runs can certainly take place on trails, but climbs may elevate your heart rate. This is okay in short, infrequent bouts, but use hiking breaks on elongated and steep pitches to keep the effort easy.

Recovery Runs

Recovery runs assist with the recuperation process between tough efforts. They can be used for the rest periods between taxing intervals or on the days following rigorous workouts, including a long run. They are purposely short in duration and kept at a very slow pace.

These jogs are a form of active recovery where your heart rate should be kept below 65% of maximum. Again, if you find yourself on hilly terrain, keep these efforts easy by incorporating hiking breaks or stopping temporarily to catch your breath.

Ultramarathon Training - How Long Long Run

Photo: iRunFar/Bryon Powell

Long Runs

The long run is the most crucial of the three endurance-based workouts for ultrarunners. It enables you to build a strong fitness base, run farther than previously possible, and, in turn, boosts race-day confidence.

Steady Long Runs

This is what usually comes to mind when thinking about running long. The objective is simply to spend a lot of time on your feet in order to:

  • Train the body to become efficient at burning fat, its optimal fuel source.
  • Become more efficient in amassing muscle glycogen, the major form of stored carbohydrates in the body.
  • Increase the size and number of muscle capillaries and mitochondria, the blood vessels and cellular factories that facilitate aerobic energy.
  • Learn to keep going when fatigued.

The pace should be easy, but the effort consistent. Depending on the terrain and your ability, short walk breaks may be necessary to keep your heart rate below 70% of its maximum.

Carbohydrate-Depleting Long Runs

I recommend you do this workout first thing in the morning, because only water (coffee or tea without sugar or creamer is also allowed) and electrolytes are permitted until the run is complete. This technique teaches the body to use fuel stores more sparingly and perform more efficiently on low blood sugar. These runs are very taxing on the body and spirit, and should therefore be limited to training runs that are three hours or less and placed three or four weeks apart. Their use is practical in early season training when weekly intensity levels are low.

Fast-Finish Long Runs

These workouts are the exception to the typical long-run theory that time on feet is all that matters. They are the most challenging component of our endurance-based training. Just as the name implies, the goal is to finish fast or with a high level of perceived effort. These runs make you a stronger runner, build your confidence, and become race-day habit-forming. Due to the amount of energy expended on the back end, fast-finish sessions are slightly shorter than the standard long run.

The workout begins at the aforementioned steady long run pace (conversational), but you increase the effort and/or pace to near marathon-race intensity (roughly 80% to 85% of maximum heart rate) toward the end. For newer runners or early season training, the fast-finish portion can range from two to three miles. For more experienced runners and peak season outings, the fast finish can increase to as much as eight to 10 miles. Keep in mind that if you are training on hilly or technical trail, aim for marathon effort, as a marathon-race pace will be too difficult to sustain.

Pace-Changing Long Runs

Much like the fast-finish long runs, pace-changing long runs call for increased periods of effort. However, instead of the tougher effort coming at the end of the run, surges are dispersed throughout. These runs simulate hills for those training in flat country, mimic what it can be like to mix it up with race-day competitors and, simply put, they are fun and challenging. Here are two of my favorites:

  • Speedy Pace Changer: 13 to 15 miles total. Warm up for two miles of easy running. Then surge for 30 seconds at 5-kilometer race effort every six to eight minutes for the remainder of the run. Run easily between surges.
  • Stamina-Booster Pace Changer: 13 to 15 miles total. Warm up for two miles of easy running. Then surge for one minute at half-marathon race effort at the start of each remaining mile. Run easily between.

Back-to-Back Long Runs

Piggybacking long runs has proven effective for ultrarunners racing beyond the 50k. It mimics ultramarathon race-day fatigue, but allows for a night’s recovery between sessions. Adequate spacing of back-to-backs, approximately four to five weeks, will assist with proper recovery. It is important to slowly progress into these workouts, especially for those inexperienced with high mileage, by starting with relatively short back-to-backs during the pre-season months and building on those as race day approaches.

Here are two examples of back-to-backs:

  • The Western States 100 Memorial Day weekend training camp comprises three consecutive long runs totaling nearly 70 miles on the actual race course.
  • Do a steady long run one day followed by a fast-finish long run the next. This is especially challenging because you will be running hard the second day on fatigued legs.
Long Run - Ultramarathon Training

Photo: iRunFar/Eszter Horanyi

Running, Not Racing

For experienced ultrarunners, participating in several ultramarathons in lieu of solo steady long runs or fast-finish sessions can prove beneficial. If you choose this approach, you must be careful to truly treat the races as training runs and not all out efforts. For example, take Scott Jurek’s masterfully crafted buildup to his June 2004 Western States 100 victory and course record by using spring races at training stimuli, not all-out efforts.

Besides a local winter fat ass event, his last race effort before this ramp-up was in early August 2003. He arrived in 2004 fresh, uninjured, and determined. In March, he opened his season with the Way Too Cool 50k; in April, he tackled both the Zane Grey 50 Mile and the Leona Divide 50 Mile; and, in May, eight weeks before the Western States 100, he ran the Miwok 100k. At Zane Grey, after I caught up to Scott late in the race, he remarked, “Phew! The training miles are catching up to me today. But this is by design. This is only a stepping stone to bigger things in June.”

As the distances elongated, the race before prepared him for the next and, as a result, he grew into 100-mile winning form. By never losing sight of his true objective of the Western States 100, Jurek turned four classic trail races into perfect training efforts on his way to winning his goal event.

How Long Should Long Runs Be?

According to numerous online dictionaries “long” is defined as: extending for a considerable distance. However, glance a little lower in the list of definitions and you find terms that describe what “long” can become if you aren’t diligent with training or maintaining self-control: tedious, subject to great odds, having excess, or stressed.

In order to avoid the latter definitions, understand that long distance is a relative concept and varies for each individual. Literature suggests that the minimal distance of a long run for a trained athlete begins at approximately 90 minutes, when the use of the body’s glycogen stores becomes stressed, while keeping injury and overtraining risks low. Ultrarunners push this envelope repeatedly.

When do the risks begin to outweigh the benefits as the length of these runs increase? To determine the most advantageous distance a given runner should cover during a long run, several factors should be weighed: running experience, injury frequency, age, and the target race.

Here are a few more considerations for planning your long runs:

  • First-time ultrarunners with limited-to-no marathon training should save their ultramarathon debut for race day. A conservative approach will allow for an uninterrupted, injury-free training cycle, and allow first-timers to toe the starting line with the best chance for success. Runners who have completed several successful ultras and have a year or two of consistent ultramarathon training volume under their belt can and should explore more aggressive long-run distances, fast finishes, and back-to-back long runs.
  • Runners who fall victim to persistent or reoccurring injuries with high-volume training due to improper technique, scheduling, or biomechanics should take a conservative approach with their long runs. In this case, less is more. Starting a race 80 to 90% prepared gives you a better chance of finishing than being unable to participate due to an injury sustained during an aggressive training cycle. [Author’s Note: We discuss ways to correct some of these issues in Cross Training for Runners, Ultramarathon Training Volume, and Running and Recovery.]
  • Some of the most competitive ultrarunners on the circuit today fall in the masters category. Though they rack up impressive race results and complete some fantastic training sessions, they need more recovery than do their 20-something counterparts.
  • Shorter events, like 50ks, don’t require the massive hours of weekend training or potentially stressful back-to-back long runs as do the longer ultras. Getting the hang of this shorter distance is a good starting point for the ambitious ultrarunner who wishes to progress to 50-mile, 100-mile, and 24-hour events.
  • Consider the concept of time versus mileage: Mountain and trail running is relatively slow-going, so running for time alleviates the pressure of having to cover a predetermined mileage
  • Adjust the length of the long run to gel appropriately with your most recent training load. Early in a training cycle, temper your body with long-run distances that are safe. A good guideline is to restrict your long run to 20 to 30% of your weekly volume. For example, if you’re a 40-mile-per-week runner, long runs should hover around eight to 12 miles. Use this rule of thumb for a few months, then you can safely begin to explore longer-distanced outings that will prepare you for the specifics of your goal even
  • The frequency of tough long runs can be altered. Don’t be afraid to extend the typical seven-day training cycle. Many runners have been successful with a 10-day or 14-day long run rotation.
  • Training on the same terrain as your race is key, but don’t let terrain specificity rule your long-run location choices. Variation in topography allows for both mental and physical reprieve
  • Scheduling a recovery week every three to four weeks, where the long run’s distance is cut almost in half, allows the body to absorb recent training while preparing for the subsequent weeks’ long runs.

Keeping in mind the above considerations, each runner can adjust their own training to fit their specific needs and ability levels. The long-run progression isn’t just a seasonal concept; it is a lifelong endeavor. The volume and intensity of your long training runs can and will increase as your body adapts to the workload over the years.

Ultramarathon Training - Endurance Workouts

Photo: iRunFar/Eszter Horanyi

[Author’s Note: Since no two ultrarunners nor their training grounds are alike and the ultramarathons and ultra-distance adventures to choose from are so diverse, it’s nearly impossible to assign numbers to long run length and frequency that will work for everyone. Instead, this column provides a general framework and suggests how to approach and reach your maximum training potential.]

Call for Comments

  • How do long runs fit into your ultramarathon training?
  • Do you run any back-to-back, carbohydrate-depleting, or fast-finish long runs in your training? If so, how?
  • Are you able to run long races as training runs without “racing” them?
  • Have any questions about the place of any endurance-based workouts in your training?


  • McMillan, Greg. The Marathon Long Run on McMillan Running (April 7, 2012).
  • McMillan, Greg. McMillan Running Company’s Online Coaching General Training Information Packet. Flagstaff, AZ: McMillan Running Company. Print.

[Editor’s Note: As one of iRunFar’s best training articles, we’ve worked with author Ian Torrence to update this article before resharing it.]

Ian Torrence

Ian Torrence has more than 12 years of experience coaching runners of all levels. Ian has completed more than 220 ultramarathons, with 50+ wins, since his first ultra finish at the 1994 JFK 50 Mile. Ian and his wife, Emily, are online coaches at Sundog Running. Information about his coaching services can be found at SundogRunning.com.