Fartlek Runs: The Simple, Flexible Way to Run Faster and Build Endurance

Fartlek runs, meaning “speed play” in Swedish, are a form of continuous training that blends easy running with bursts of faster effort, all without the rigid structure of traditional interval workouts.

Instead of sticking to exact distances or times, you vary your pace based on feel, terrain, or landmarks, making the session both flexible and intuitive. The main objective of a fartlek workout is to improve speed, endurance, and your ability to change gears efficiently during a run.

Because the effort fluctuates, you get many of the same benefits as structured speed sessions—like intervals or tempo runs, while keeping the workout more relaxed and accessible.

Fartleks are a great option for runners of all levels: beginners can ease into speed work without pressure, while more experienced runners can use them to sharpen fitness, build race-specific strength, and add variety to their training.

What’s the Difference Between Fartlek Workouts and Interval Training?

The key difference between a fartlek workout and traditional interval training is structure.

Interval workouts are typically done on a track or measured course with set distances, paces, and rest periods, often involving full stops or very controlled recoveries.

Fartlek runs, on the other hand, are continuous and more flexible—you can do them anywhere, on any terrain, without strict timing or distances.

In a fartlek session, you simply weave short bursts of faster running into an otherwise easy run. Instead of stopping between efforts, you ease back into a comfortable pace for recovery, keeping the run fluid and uninterrupted.

Like any quality session, a proper warm-up is essential before starting your faster efforts. Then, once you finish your final surge, you continue running easily and finish with a relaxed cool-down to bring your heart rate back down.

You can think of a fartlek as a “sandwich”: an easy warm-up and cool-down on the outside, with speed play efforts layered into the middle of your run.

In this way, it’s similar to a tempo run in that the entire workout is continuous. You’re simply changing gears within the run rather than stopping between intervals.

This makes fartlek training a more natural, intuitive way to build speed and endurance, especially for runners who prefer a less rigid approach to structured workouts.

What Are the Benefits of Fartleks?

There are many benefits to fartlek training, both from a global perspective when comparing this type of workout to traditional interval training and, more specifically, when using these sessions as one of your options for speed work in your training plan.

• More approachable for beginners as they are less stressful, formal, and intimidating than traditional interval training on the track.
• Can be used in conjunction with heart rate training to guide your hard efforts.
• Flexible in terms of the terrain.
• Build aerobic and anaerobic fitness because you are interspersing faster running with your normal running pace without stopping. This requires you to rely on both aerobic and anaerobic metabolism while building endurance and speed training.¹Bacon, A. P., Carter, R. E., Ogle, E. A., & Joyner, M. J. (2013). VO2max Trainability and High Intensity Interval Training in Humans: A Meta-Analysis. PLoS ONE, 8(9), e73182. https://doi.org/10.1371/journal.pone.0073182
• Can improve VO2 max²Mazurek, K., Zmijewski, P., Krawczyk, K., Czajkowska, A., Kęska, A., Kapuscinski, P., & Mazurek, T. (2016). High intensity interval and moderate continuous cycle training in a physical education programme improves health-related fitness in young females. Biology of Sport, 33(2), 139–144. https://doi.org/10.5604/20831862.1198626 or aerobic capacity.³Scribbans, T. D., Vecsey, S., Hankinson, P. B., Foster, W. S., & Gurd, B. J. (2016). The Effect of Training Intensity on VO₂max in Young Healthy Adults: A Meta-Regression and Meta-Analysis. International Journal of Exercise Science, 9(2), 230–247. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4836566/
• Entertaining workouts: The speed play intervals can break up the monotony of a long-distance run at a steady pace while improving aerobic endurance.⁴Kumar, P. (2015). Effect of fartlek training for developing endurance ability among athletes. ~ 291 ~ International Journal of Physical Education, Sports and Health, 2(2), 291–293. https://www.kheljournal.com/archives/2015/vol2issue2/PartE/3-3-75-957.pdf
• Teaches your mind and body to throw in surges and to be comfortable shifting gears and running faster, which can be useful in race day situations.
• Allows runners to become accustomed to a variety of running speeds.⁵Mazurek, K., Zmijewski, P., Krawczyk, K., Czajkowska, A., Kęska, A., Kapuscinski, P., & Mazurek, T. (2016). High intensity interval and moderate continuous cycle training in a physical education programme improves health-related fitness in young females. Biology of Sport, 33(2), 139–144. https://doi.org/10.5604/20831862.1198626For example, you can add surges at your 5K pace or even mile pace, goal running pace for a marathon or long-distance race.
• Scalable to different distances and running paces.
• Easily replicated when you are cross-training, if you are injured, by making a hard effort to pick up intervals on whatever cross-training modality you are doing. For example, you can do this workout in the pool while running in deep water or use a spin bike or an elliptical trainer.

As mentioned, one of the best things about fartlek workouts is that they are completely customizable and scalable based on your fitness level, where you are in your training plan, and the running pace you use for your fartlek runs.

How do you Structure a Fartlek Training Session?

There isn’t one single way to do a fartlek workout. This is the beauty of it.

The versatility allows beginners, 5k-ultramarathon runners, cross-country runners, and everyday individuals looking to improve fitness and run faster to incorporate a fartlek session into their training by designing a workout that meets their fitness level and training goals.

#1: 20 Minute Fartlek Run

For beginners, one of the first speed work sessions I incorporate into a training plan is a 20-minute fartlek run. 

This workout is great for runners who have built enough aerobic endurance to run for 20 minutes without stopping and are ready to start incorporating faster running.

Here is what you will do:

1. Warm up with three minutes of easy jogging. (RPE 2-3)
2. Run two minutes at your easy running pace. (RPE 4)
3. Do 8 x 30 seconds at an RPE of 7-8, with 60 seconds at your easy running pace, as the recovery intervals between each pick-up.
4. This would be 12 minutes of the fartlek run portion of your run session.
5. Because the warm-up took five minutes and you have 12 minutes of speed work, you will use the last three minutes as a cool-down at an easy jog. (RPE 1-2)

#2: Half Marathon Fartlek Workout

In my work as a running coach, it seems that the half-marathon has become the most popular race distance among my athletes.

This workout is a great way to break up a longer-distance run while still doing a faster workout than regular tempo runs.

Here is what you will do:

1. Warm-up by running 15-20 minutes (RPE 3-4).
2. Then, run 5×1 minute at your goal half-marathon race pace (RPE 5-6) with 30 seconds of recovery at your easy pace in between each of the half-marathon pace surges.
3. Then, run 5×1 minute at 10k running pace (RPE 6-7) with 45 seconds of recovery in between each of the 10K running pace surges.
4. Then, run 5×1 minute at 5k pace (RPE 7-8) with 60 seconds of recovery between each interval.
5. Finish with 5×30 seconds at VO2 max pace or faster (RPE 8-9), trying to hit a fast pace as if you are closing in on the finish line of a big race. Take 90 seconds of recovery between each one.
6. End the fartlek session with a few minutes of easy jogging to cool down. (RPE 1-2)

#3: Fartlek Fun

This is a fun fartlek workout that doesn’t require your running watch. 

Instead of doing timed interval training, you will use landmarks on your run, such as mailboxes, lampposts, telephone poles, or street signs to determine when you will start your hard effort and when you will start each of your surges.

For beginners, I suggest using mailboxes if you live in a relatively dense neighborhood with lots of houses.

Basically, you will run at a hard effort from one mailbox to the next. Then you will run at your easy running pace until you reach the next mailbox.

What makes the mailboxes fartlek run fun is that different neighborhoods and streets along your running route will have varying mailbox spacing, so you might get lucky and get a nice recovery, or you might get challenged by a long stretch of harder running followed by a really short recovery.

If you want something a little more predictable with your pick-up distances, you can use lampposts or telephone poles.

Most cities and neighborhoods have fairly uniform distances between them, so you can alternate between faster running and easy running speeds as you hit each road marker.

To really challenge yourself, you can play around with the running speeds that you use in a cyclical manner.

For example, start with your half-marathon pace, then do 5k pace for the next hard effort, and then do all-out sprinting for the next one.

Learning how to shift gears and change your high-intensity effort is a great way to increase your heart rate, build anaerobic strength, and really capitalize on the “speed play“ component of the Swedish fartlek training method.

After all, if this training method is called speed play, it should be fun, right?

For a guide on how to do tempo runs, check out the next article:

References

• 1
  Bacon, A. P., Carter, R. E., Ogle, E. A., & Joyner, M. J. (2013). VO2max Trainability and High Intensity Interval Training in Humans: A Meta-Analysis. PLoS ONE, 8(9), e73182. https://doi.org/10.1371/journal.pone.0073182
• 2
  Mazurek, K., Zmijewski, P., Krawczyk, K., Czajkowska, A., Kęska, A., Kapuscinski, P., & Mazurek, T. (2016). High intensity interval and moderate continuous cycle training in a physical education programme improves health-related fitness in young females. Biology of Sport, 33(2), 139–144. https://doi.org/10.5604/20831862.1198626
• 3
  Scribbans, T. D., Vecsey, S., Hankinson, P. B., Foster, W. S., & Gurd, B. J. (2016). The Effect of Training Intensity on VO₂max in Young Healthy Adults: A Meta-Regression and Meta-Analysis. International Journal of Exercise Science, 9(2), 230–247. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4836566/
• 4
  Kumar, P. (2015). Effect of fartlek training for developing endurance ability among athletes. ~ 291 ~ International Journal of Physical Education, Sports and Health, 2(2), 291–293. https://www.kheljournal.com/archives/2015/vol2issue2/PartE/3-3-75-957.pdf
• 5
  Mazurek, K., Zmijewski, P., Krawczyk, K., Czajkowska, A., Kęska, A., Kapuscinski, P., & Mazurek, T. (2016). High intensity interval and moderate continuous cycle training in a physical education programme improves health-related fitness in young females. Biology of Sport, 33(2), 139–144. https://doi.org/10.5604/20831862.1198626