What is a Fartlek in running? The Speed Session You Should Be Doing

You probably giggled a bit when you first heard the term “Fartlek” and wondered what the heck it had to do with running. When I told my husband I was writing a piece on Fartlek, his exact response was, “What did you say?!” while looking at me with an amused and confused expression. But, it’s actually a very common running workout!

A Fartlek is a type of running workout that implements speed and literally means “speed play” in Swedish. In this type of workout, runners have freedom to alternate continuously between their perceived easy and hard paces in an unstructured way.

Fartlek workouts, despite their funny-sounding name, truly help runners develop their speed in a fun, unique manner that is unlike any other typical running workout. To learn more about this wonderful and effective Swedish contribution to the running community, read on!

The History of Fartlek

So just how did the term “Fartlek” come to be?

In the 1930s, Swedish running coach and former Olympian, Gustaf “Gösta” Richard Mikael Holmér, was coaching the Swedish national cross-country team that was performing pretty poorly. The team was feeling discouraged and maybe a little burned out.

Holmér wanted his runners to improve both their speed and endurance for upcoming competitions, and he was unhappy with their current workout options. So Holmér invented a workout that combined speed and endurance training in one. He had his team alternate between running faster-than-race pace, and easy pace, in this workout. Holmér named this type of run Fartlek which translates to “speed play” in English.

After incorporating Fartlek runs in their training, Hozlmér’s runners many world records in several middle and long-distance races.

What is a Fartlek run exactly and how do you do one?

Fartlek runs are meant to be fun and playful speed workouts, where runners are given a lot of freedom to decide when to push their pace, and when to back off.

A Fartlek was originally intended to be unstructured – an easy run with random uptempo bursts sprinkled in, according to Canadian Running Magazine. While it sounds a lot like interval training, Fartlek are not true interval workouts, for two reasons:

1) There are no prescribed paces in this fairly unstructured form of workout, and
2) Fartleks are continuous, and don’t include any stopping or walking recoveries between the faster sets

Essentially, Fartlek runs have infinite possibilities!

Women’s Health Magazine describes Fartlek as “impulsive” in nature. The idea is for a runner not to overthink too much, but to just play around with going faster within a workout when it feels natural to do so. Overall, it allows for a more enjoyable run while still getting the benefit of implementing some speed.

Nowadays many coaches and training programs incorporate some structure to Fartlek workouts, while maintaining the original spirit of the workout. Strength Running explains that there are four general ways that Fartlek can be designed:

  • Fixed distance. Example: run hard between every other light pole for 10 minutes.
  • Fixed time. Example: run hard for 30 seconds, then run easy for 1 minute, 8 times.
  • Varying Distance. Example: run hard to the light pole. Then easy to the tree. Then hard to the second mailbox.
  • Varying Time. Example: run hard for 30 seconds. Then easy for 2 minutes. Then hard for 5 minutes. Then easy for 1 minute.

Does one of these sound right up your alley? Luckily you don’t need any permission to fit these into your training, so go ahead and pick one that sounds fun and go for it!

Benefits of Fartlek Training

Fartlek workouts are wonderful for runners. Not only because they are fun and unique, but because of the myriad of benefits runners can reap from them.

Doing a Fartlek run can help:

  • Build mental toughness: since Fartlek are run continuously, without full recovery breaks, you will have lots of practice mentally pushing yourself to keep going through the entire workout. Tempo runs are another great mental-endurance building quality session so be sure to read about those next.
  • Build confidence as a runner: especially for beginners, the hard segments of each Fartlek help you practice sustained harder efforts going by feel. You don’t have to worry about hitting specific paces but can still push yourself. All the while you’ll be becoming a stronger runner!
  • Stimulate a runner’s creativity: there is no single “right” way to Fartlek. Want to run hard until you’ve passed two trees? Great! Want to run easy for five minutes and then run hard for one minute? Also great!
  • Make workouts surprising and fun: variety is the spice of life, and with Fartlek workouts, no two have to be the same. The joy of Fartlek is in the freedom it gives runners, so break out of your more rigid interval sessions and play with your speed and interval lengths!
  • Improve endurance and speed, making you a stronger runner: by alternating between easy and harder paces while running continuously, your body will improve its delivery of oxygen to your muscles, will reduce its resting heart rate, and will yield better overall running endurance, as explain in Women’s Health Magazine.

What pace is best for Fartlek training?

The proper paces to run Fartlek are up to you to decide!

You just want to make sure that the “ons” are noticeably faster than the “offs” when you’re slowing down. You can decide when to speed up, and for how long. You can also decide just how much to speed up within each surge, how long to take to accelerate up to that speed, or how long to decelerate back to your easy pace. You might even try varying the difficulty level of each “hard” portion of your Fartlek, perhaps progressively making them faster each time.

Don’t worry about looking at your watch to get a specific pace, otherwise that takes away the playful nature of these workouts as they are designed.

One caveat about Fartlek: you still need to make sure that you are never going “all-out” or running at 100% effort. Keeping it to a 5 – 8 on a 1-10 Perceived Rate of Exertion scale will ensure you’re not overdoing it. Always avoid doing too much, too fast, too soon, or else you’re putting yourself at higher risk for injury. If the speed segments are shorter, you can go a bit faster, but don’t quite as hard if the speed segments are a bit longer. The more you’ll do them the more you’ll get a feel for what works for you!

How long should a Fartlek be?

The beauty of Fartlek is that there is no requirement to run a certain length of time or distance.

But it can depend on what you’re training for (though you don’t have to be training for anything to get the benefits of doing a Fartlek).

Shorter Fartlek sessions work well for beginners or runners training for shorter races, such as a 5k. The fartlek portion may be as short as ten minutes (though there isn’t anything wrong with going for longer.)

Half-marathon and marathon runners often do best when completing a Fartlek run within a longer endurance run, begun with a proper warm-up and ending with a cool-down. This will allow you to get in the mileage you need to train properly for these longer events while still getting the speed benefits the Fartlek can provide. In this case, you may spend upwards of 30-45 minutes doing the Fartlek portion within your run with the rest of the mileage run at your easy pace.

RELATED: A Guide to How Much Mileage Marathon Runners Run

Who should incorporate Fartlek into their training?

Fartlek runs are beneficial for all runners, ranging from beginners all the way up to elites. Everyone can improve running fitness by incorporating Fartleks into their training.

Beginner or Comeback Runners

For beginner runners, or runners coming back from a prolonged break, Fartlek can introduce speedwork in a simple, pressure-free way because runs are completely based on feel, not specific paces.

Intermediate and Advanced Runners

For more experience runners, Fartlek is a great transitional workout between training phases. They can help runners transition from base-building into more focused speedwork that comes with race training. Or, they can help seasoned runners transition from an off-season back into base-building, while still incorporating faster speeds.

Because Fartlek runs incoporate speed, this is considered a quality workout or “speed” day. Because it’s important to alternate hard and easy days, be sure to do a recovery run the next day.

Four Examples of Fartleks You Can Try Right Now

Even though you have complete freedom to do your Fartlek how you like, it’s always nice to have a few ideas for how it might look. Here are 4 options you can implement into your training.

For each workout, complete a dynamic warm-up for about 5-10 minutes. Begin your Fartlek with an easy 1-2 mile run. Complete your Fartlek with a 1-2 mile easy run to cool down.

  1. Random Fartlek: Pick landmarks at random to surge to. Once you’ve reached that landmark, slow back down to your easy pace until you spy another landmark you want to surge to. Repeat for 5-10 minutes.
  2. Follow the Leader: In a running group, have everyone run easy, in single-file formation. The person at the very back will surge to the front of the line and will decide how long to keep surging, and everyone behind him or her must follow the leader. After the group has returned to an easy pace, the new person at the back decides when to surge ahead and repeats the process. Complete 2 rounds (everyone gets to play “leader” twice).
  3. Time-based Fartlek: Alternate 1 minute of hard running, followed by 1 minute of easy running, 8 times.
  4. Ladder Fartlek: Repeat twice: 2 minutes hard, 2 minutes easy. Repeat 4 times: 1 minute hard, 1 minute easy. Repeat 4 times: 30 seconds hard, 30 seconds easy.

These could also be done in sets with easy running done in between. If you’re training for a half or full marathon and need to get a longer run completed, consider trying something like #3 for two-three sets.

Strides versus Fartlek: How They’re Different

Strides and Fartlek runs are both effective ways to build your speed and are sometimes confused because they are both shorter bursts of speed. But they are very different from one another in principle and execution.

Strides: Strides are bursts of speed run over a set distance, usually about 100 meters. Strides require full recovery in between each round of speed, whether by standing still, or by walking slowly back to the start. Strides can occur at the beginning of a traditional speed workout or race to prepare your body for the upcoming work, or at the end of an easy run. We explain more in our article, Strides in Running: Learn How to Do Them and Become a Faster Runner.

Fartlek: By contrast, Fartlek workouts are their own type of speed workout, with surges of speed built into an easy run. Fartlek give runners a lot of freedom in the paces to run and how to vary those paces. Fartlek do not permit full recoveries in between bursts of speed; rather, a runner returns to an easy pace and runs continuously until the workout is completed.

The bottom line? Fartlek are about pacing freedom and utilizing variety mid-run. Strides are rigid and fixed, and are typically completed immediately after an easy run is completed.

Now that you know all about Fartlek, give them a try yourself sometime as a way to shake up your running routine and incorporate more fun!

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