Coach D's Guide to Fartlek Runs

Fartlek runs can be a fun and versatile addition to any runner's training plan. In this article, I'm going to cover everything you need to know about this adaptable workout so that you can avoid the potential pitfalls and get the most out of each session.

What are Fartlek runs? and why such a funny-sounding name?

It may sound funny in the English language and indeed there are always some giggles when I mention it in my group coaching sessions. But it makes perfect sense in the native tongue that spawned it = Swedish.

Fartlek is a Swedish term for a specific style of interval training.

Fart = Speed

Lek = Play

So put simply it means to play with your speed during a run/training session.

Who invented Fartlek?

The Swede that is credited with coming up with the idea was - Gustaf Richard Mikael Holmér. Or Gösta Holmér to his friends.

In the 1930s, he was motivated to come up with a better way for his cross country running teams to train. So that they could challenge the dominant Finnish runners of that era.  

Gustaf knew that he needed to develop his runner's speed and endurance. So he combined those elements in a single training session. By getting his runners to alternate from a faster-than-race-pace to easy paced running.

It was a simple concept and it proved to be very effective. The principles of this simple interval training system have been used by many runners ever since.

It's no longer a training technique just for runners either, as football (soccer) players, basket ball teams, swimmers and cyclists have also adopted fartlek into their training regimes.

How do you do a Fartlek session?

If you type this question into google you will get a lot of examples suggesting something like this:

  • Warm up  
  • Run fast at 5k race pace or faster for 1 minute, then jog at an easy pace for 5 minutes to recover for (repeat x number times)
  • Cool down

To me that's just a time based interval session - which is great - but in my opinion it's too structured to be considered a true fartlek workout. Besides, where's the "PLAY" in the above session? 

A potential draw-back of this example time based interval session - is that you need something to time each interval. Usually a running watch that can be pre-programmed to beep at you to change things up or slow down.

Don't overthink it - Just Play

But for me the beauty of a fartlek session lies in it's lack of structure and the fact that you don't need any technology to tell you when to speed up or slow down. You just decide when to speed up, how fast to go, how long to maintain that speed and when to slow down - simple.

My view is that Fartlek runs should be fun. As the name suggests it contains an element of play

The fact that you decide when to vary your pace and for how long is what makes it playful and quite liberating. Though it may not suit people who find comfort in the repeatable structure of a timed interval session.

Run by feel 

Not having to worry about timing or pacing are the main things that I enjoy about Fartlek. 

Once you're nicely warmed up you can start to add in little bursts of speed. Because there is no set structure or a specific pace to aim for - you can't really get it wrong. The structure of the session is basically a blank canvas for you to experiment with and enjoy.

If you're running on the road (alone or with friends) you can simply note something ahead of you, like a street light or road sign and decide to increase your pace until you reach it. Then once you've recovered - chose another point ahead of you - it can be further away or closer than the previous target. 

You don't have to take off like a bat-out-of-hell when you decide to change your pace-up. You can vary how quickly and how much you ramp up the pace. The surge can be slow to start with, building to a crescendo.

Equally you don't have to drop your speed abruptly either. Sometimes you can throttle-back gradually too.

It's not just the faster sections you can play with either. You can play with the pace and duration of your recovery elements too. Sometimes dropping down to a very slow jog. With other recovery sections run at a slightly faster or even fluctuating pace.

All of this 'random' variation of pace makes you better at being able to "listen" to your body and understand what it's capable of. And what it feels like to be pushed and to surge at random - which is something you will most likely have to do in a race scenario. When you will need to react to the circumstances you find yourself in at that time. Surging to overtake other runners for example. Or to keep ahead of them, so you can hold a better racing line through a corner.

Work to rest ratio

Whilst there's no set rule as to specific pace and duration of each of the faster intervals. On the whole you want to spend the majority of your fartlek runs at an easy pace. This includes the beginning/end as part of your warm up and cool down and for recovery between the faster paced elements.

Otherwise you risk overdoing things. A good approximate work to rest or fast to easy pace ratio to aim for would be to follow the classic Pareto principle of 80/20.

That is 80% of the total run at easy pace and 20% at faster pace. Another way to look at it - especially if you use a heart rate monitor, is to stick in the aerobic zone for the 80%. Then allow yourself to stray into the anaerobic territory for the 20%.

Where is a good place to run a Fartlek session? 

The short answer to this - is absolutely anywhere. Because it's so flexible and you don't need any special equipment for timing or pacing you can do it wherever you run.

  • Road
  • Trails
  • Running Track
  • Grass Field/Park
  • Treadmill
  • Beach
  • Hills
  • Indoors, outdoors or early doors...

How often should you do a Fartlek workout? 

Because fartlek runs are classed as a speed-work session, as a general rule of thumb most amateur runners should include a maximum of 2 speed sessions a week. Both sessions could be fartlek runs or you could swap one for a more structured interval session.

For beginners I would recommend only one speed session a week and it shouldn't be the day before or after another hard session. So an example of how to fit in a fartlek session for someone that runs 4 times a week would be something like this:








Rest Day

Fartlek Run

X-train or Rest

Tempo Run

X-train or Rest

Easy Run

 Long Run

I like to put fartlek runs at the beginning and end of my training plans. Because they're a great way to introduce speed sessions into a trining plan. Plus because they're not really repeatable - due to their random nature. It makes them ideal to have at the end of a training plan in the run-up to a race. You can't really compare your previous performances, and they're fun - so they can help reduce any performance anxiety that may be building.

Are Fartlek Runs Suitable for Beginners?

Absolutely, I think they're a great way of introducing new runners to speed work. 

If you're starting from complete scratch - following a run/walk program like couch to 5k. Then finish that first before you start to change things up a bit.

But after that - go for it. It's a fantastic way to get some variety and challenge yourself to improve.

For beginners, I'd also recommend starting with a lower work to rest ratio of 90/10 and building up gradually. Also stick to shorter runs initially too.

Fartlek runs are suitable for all ages and abilities too.

Is Fartlek training suitable for groups? 

Definitely. They're one of my favourite ways to include an element of speed work into group sessions. Which I do in one of two ways:

  • Get each member of the group to take a turn at deciding on when to surge, along with how far and at what intensity/pace. They chose a point ahead for the group to speed up or race to. This is best for smaller groups when out on trail or road runs.
  • Indian File. This is better for larger groups on a field or at a track. But can also be done on road or trail too. Providing that there is enough room to overtake safely and without causing a nuisance to other pedestrians.

If you've not heard of Indian File running before. It's basically just running at easy pace in single file formation. And the runner at the back will surge to the front. Once they get to the front, the runner that is now at the the back will surge to the front etc. The video below is a good demonstration of this at a running track.

 Fartlek runs are not just for amateur runners. Many elite international athletes use them in their training too. They're a staple of the training camps of top class Kenyans.

What is Fartlek training good for? 

Fartlek runs are good for so many things - including:

  • Fun
  • Variety
  • Simplicity
  • Confidence
  • Builds Strength
  • Improves VO2Max
  • Enhances Fat Burning
  • Better Body Awareness
  • Simulates Race Conditions
  • Boosts Speed & Endurance

Advantages & Disadvantages of Fartlek training? 

Fartlek Runs Infographic
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About the author 

Coach D

Hi, I'm Dave. I'm a UK Athletics qualified and licensed Coach in Running Fitness (CiRF), Endurance Event Group Coach and Certified Running Technique Coach. I coach groups and individuals of all abilities both online and in person.

I particularly enjoy coaching beginner and improver runners in the 40+ age range.

I'm also a regular recreational runner and I've been competing in races from 5k to marathon distance for over 30 years.

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