Fartlek Interval Training for Runners

Fun Way to Improve Your Speed and Endurance

Running a path near the Pacific Ocean.
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Fartlek, a Swedish term that means "speed play," is a form of interval or speed training that can be effective in improving your running speed and endurance. Fartlek running involves varying your pace throughout your run, alternating between fast segments and slow jogs.


Unlike traditional interval training that uses specific timed or measured segments, fartleks are more unstructured. Work-rest intervals can be based on how the body feels. With fartlek training, you can experiment with pace and endurance, and experience changes of pace.

Many runners, especially beginners, enjoy fartlek training because it involves speed work, but it is more flexible and not as demanding as traditional interval training. Another benefit of fartlek training is that it doesn't have to be done on a track and can be done on all types of terrain, such as roads, trails, or hills.

Fartlek training puts a little extra stress on your system, eventually leading to faster speeds and improving your anaerobic threshold.

How to Do Fartlek Workouts

To do a fartlek workout, try introducing some short periods of slightly higher pace into your normal runs. Maintain the faster pace for a short distance or time intervals, such as 200 meters or 30 seconds. The intervals can vary throughout the workout, and you can even use landmarks such as streetlights or telephone poles to mark your segments.

Once you complete a fast segment, slow your pace to below your normal running pace until you have fully recovered and your breathing has returned to normal. Then return to running at your normal pace, and incorporate more slightly fast intervals later in the run.

Sample Workout

Here's what a sample beginner fartlek workout would look like:

  • 10-minute warmup at an easy pace
  • 1 minute on (fast pace), 2 minutes off (easy), 2 minutes on, 1 minute off
  • Repeat the fartlek set 3 to 4 times
  • 10-minute cool down at an easy pace

Keep in mind that fartlek training is meant to be free-form and fun. If you're setting a timer, it's just interval training. Think of landmarks on your run that would result in this type of pattern. When you are running with a friend, think of trading off selecting landmarks to add more variation in your fartlek runs.

Treadmill Fartlek Workouts

When you don't want to enjoy your speed play outside, you can do a treadmill fartlek workout. If you watch television during your treadmill time, you might use commercials as a time to go into a sprint. At the gym, you can make a game of it and do your sprint when a new person gets onto or off of a machine.

Perhaps sprint during the chorus of songs on your playlist or when certain songs play. This can help relieve treadmill boredom. One precaution is that you'll need to use the buttons on your treadmill to increase and decrease the pace. It can be wise to use longer durations for each phase so you have less contact with the control panel.

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2 Sources
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  1. Bacon AP, Carter RE, Ogle EA, Joyner MJ. VO2max trainability and high intensity interval training in humans: a meta-analysis. PLoS ONE. 2013;8(9):e73182. doi:10.1371/journal.pone.0073182

  2. Kumar, P. Effect of fartlek training for developing endurance ability among athletes. International Journal of Physical Education, Sports and Health. 2015; 2(2): 291-293