Fartlek Runs (or Fartleks) for Speed and Endurance

Fartleks may be the worst sounding, but one of the most important foundational workouts for runners. Swedish for “Speed Play”, Fartleks focus on continuous running and interval training in the same run whereas tempo running is continuous and track intervals focus on speed. It is literally the best of both worlds, as the workout varies between “on” where you are moving at a fast pace before going “off” into a comfortable pace without stopping to rest.

Why Run Fartleks

From a physical standpoint, Fartleks target speed and endurance. During the “on” phase of the workout you are moving at a fast pace for any distance you want to target, with a focus on speed. Since this run is done on the open roads (or even while running trails), you will likely be in speed mode for a set period of time versus knowing how far the distance is for a repeat. While you can use a GPS watch to calculate distance, for example running 400 meters in the “on” portion, running at speed for a full minute is just as effective.


Fartleks build endurance as this is a continuous running workout. During the “off” phase of Fartlek, your goal is to downshift into a jog, or for more advanced runners 75% of the pace you just completed, before ramping back into the next speed burst. This allows your body to get attuned to the pace variations that happen during a race while having a strong endurance workout since you never stop running.

Running Control

From a mental and physical aspect, Fartleks greatly assist with pace control and being able to respond with confidence to a race surge or struggling to get back into your pace after a tough hill or mile. They also give you clarity and intimacy into what your body is capable of managing from a pace perspective without feeling like you are out of your league. This is achieved by the sense of pace gained while moving on and off. If you know what is “fast” per your body, you will easily know if the pace you are trying to maintain is too fast or for how long you can maintain a fast pace in a race scenario.

Never a Boring Run

Beyond race day, Farteks are a great way to break up the monotony of running if you feel stuck in a rut. You can run Fartleks anywhere, choosing to be highly structured with a GPS watch for distance, running between objects, for a set amount of time per repeat… or more unstructured by randomly speeding up for varying distances. They key to Fartlek running is to mix it up, challenge yourself, but enjoy the flexibility offered by this ever changing training session.

How to Run Fartleks

While the concept of Fartlek running appears simplistic, there are a few things to keep in mind to optimize this workout:

  • Warm up and cool down for at least 1 mile each
  • Find the appropriate time or distance to run for your “on” and “off” phases. This may be running between objects, such as light poles, or using a GPS watch to determine distance if you choose the distance approach. However, the most common technique is to run for a set amount of time, typically 2 minutes on with 2 minutes off
  • Your “off” pace should be 60-75% of the pace you run for your “on” pace
  • Start with 4 Fartlek repeats at 1 minute “on” and 2 minutes “off” before working your way up in repeats, with a maximum of 5 miles of Fartleks (7 miles including warm up and cool down)
  • Once you have met the challenge of running Fartleks for 1 minute on and 2 minutes off, reduce your “off” phase to 1 minute before increasing your “on” phase time. Reduced rest will offer a huge challenge to maintaining pace control while increasing mental toughness and endurance
  • Don’t slow down too fast or kick into your next repeat, but rather stride into a strong pace that is faster than your 5K race pace
  • Once you have mastered 1 minute on and 1 minute off phasing at faster than your 5K race pace, increase your “on” phase time while ensuring that you get at least half the amount of time for the “off” phase as your “on” phase (ex. If you run a 4 minute “on” repeat, your “off” Fartlek repeat should be 2 minutes)
  • If you feel like you have hit a running plateau, mix up your Fartlek routine by increasing the pace or mixing it up via varying time phases or distances (ex. Fartlek repeats of 1 minutes, 4 minutes, 30 seconds, 30 seconds, 2 minutes, and 1 minute). If you are running out of ideas, check out the guide for Ladder and Mixed Track Intervals

What to Avoid When Running Fartleks

Fartlek running has a certain amount of intensity to it that requires caution before attempting, and awareness while executing this unique running workout. Specifically:

  • Consult with your doctor before attempting Fartleks or any intense running training session/program
  • Don’t run Fartleks if you are injured or recovering from an injury


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