
Did you know that a fartlek is a great workout that can be used by runners that train for any distance? It doesn’t matter if you are preparing for a 1500m, a 10 km race, a half marathon or a marathon. It’s a type of workout that can be used by every runner, to improve endurance and speed(-endurance).
Here is my detailed advice about fartleks,including some examples of great fartlek sessions that you should try out, among which the Kenyan fartlek.
“Are fartleks when you run and then you fart on the way?”, my sister asked me when I was 16 years old and told her about a new workout I had done. ‘No, I’m sorry sis. A fartlek is a fun workout, but not that funny!” must have been my response.
The word fartlek actually comes from Swedish, where it means ‘speed play’. You play with the speed.
It started as a very unstructured workout, where runners would decide ‘on the fly’ when to speed up and when to slow down. For example, someone would run fast up a hill, then take it easy on the downhill and around the curve, then speed up until the next electricity pole, and so on.
Nowadays, most athletes do their fartleks in a more structured way, in the sense that already at the start of the training, they know exactly what kind of intervals they are going to do.
An example of a fartlek is: 3 x 3/1, 4 x 2/1, 5 x 1/1 which stands for: 3 min fast, 1 min easy (3 sets in a row), followed by 2 min fast, 1 min easy (4 sets in a row), followed by 1 min fast, 1 min easy (5 sets in a row). So that makes for 34 minutes of fartlek.
Obviously, you have to do some warm-up before you start your fartlek, and some cool-down at the end. So a 34 min fartlek will result in a session that takes close to 60 minutes in total.
The main characteristics of a fartlek are:

You alternate between fast running, and slow running. Or you alternate between a fastpace and a moderate pace. Or between a moderate pace and an easy pace. In other words, there are changes of pace – unlike when you do a tempo run, where you keep a (more or less) constant pace from start till end.
There is no walking in between. This makes it different from a regular interval session, which could have a walking recovery. A fartlek is a non-stop run of, say, between 20 and
60 minutes.
The exact pace is not determined, but depends on how the runner feels. With an
interval session you might say ‘I want to run 8 x 800m at a pace of 4.00 per km’, but
when it’s a fartlek you will just say ‘I want to run fast for 3 minutes, and then I run slow
for 2 minutes, and I repeat that eight times.’
What is the use of a fartlek session?
What I like most about the fartlek is point number 3. Most athletes feel less pressure when you give them a fartlek, than when you give them a track session. Why? Because on the track (and the same goes up when you do intervals on the road) there is a pace given. They have to complete the distance within a certain time. That gives them a bit of stress.

With the fartlek, there is very little pressure, because all you need to do is push hard for 1 or 2 or 3 minutes. The coach is not going to tell you how fast to run, other than ‘3 min on, and 1 min off’. The rest is up to you and how you feel. Sounds great, right? Exactly! And many runners actually end up pushing the pace pretty fast, some can even push harder than they do on the track, because there’s no pressure to perform.
First, this makes the fartlek an ideal training session during the winter (off) season, when you just want to train well, give yourself a good endurance and speed stimulus, but you don’t want to be too strict about the pace you’re running. Fartleks help you bridge that gap between doing easy to moderate runs, and going to the track for a workout.
Second, because they are mentally less demanding (physically not necessarily), the fartlek is an ideal workout between two harder sessions. For example, when my athletes are training for the marathon, they might do a very demanding session such as 5 x 5km at marathon pace. That’s a tough one! It can leave them physically and mentally drained for a few days. After such a 5 x 5km, most athletes don’t really feel like going to the track three days later for a session of 8 x 1km. So I might give them something like 8 x 4 min on, with 1 or 2 min off. Feels a lot easier, but it’s a similar stimulus.
Third, the fartlek is a great way to combine working on your endurance and your speed. They are basically an endurance workout, because you are often running for 30 – 40 minutes with a continuously high heart rate. However, you can also include short bursts of 1-2 minutes fast running, going up to your 5-10K race pace or even faster. So for a marathon runner, the fartlek is a great way to work on the speed. Whereas for the 5K runner, the fartlek is a good way to touch race pace, but in a very aerobic way.
Fourth, the fartlek is an ideal session to do off-road. If, like me, you love running in a forest, on trails that zig zag around trees and bushes, going up and down hills, the best way to get a quality workout in is to do a fartlek. The playful nature of the fartlek, matches with the environment. You can’t really aim for a certain pace when you’re running around curves and up and down hills, with the ground changing from paved road, to trail, to sand. So what you do is that you just alternate some harder parts and some easier parts.
What types of fartlek sessions do we have?
When it comes to the fartlek, there is really an endless list of opportunities, but here are a
few categories of fartlek that we can distinguish.
3 sets of 4-5 x 1/1. This is a good session for those of you who have never done a
fartlek before. When you have never alternated between fast and easy running,
you may not immediately judge the pace correctly. To avoid getting totally
exhausted, it’s best to do a session that has some longer recovery in it as well.
After warming up, you start with 4 to 5 sets of 1/1: one minute fast running, one
minute easy running. So this will take 8 – 10 min. Then you take anything from 2
to 5 min of easy running. Then you do the second set of 4-5 times 1/1. Then a
longer break again, followed by the third set.
It’s easy to progress the above fartlek and make it harder by removing the set
pause, adding intervals, or by making the reps longer. The typical Kenyan fartlek
consists of one hour of one of the following three variations:
Either 30 x 1/1, or 20 x 2/1, or 15 x 3/1. The Kenyan fartlek is typically done
every Thursday. If this week it’s 30 x 1/1, next week will be 20 x 2/1, or 15 x 3/1.
I have joined Kenyans on their fartlek many times in my life, from when I was in
top shape and able to follow the front of the group, to now as someone who is 48
years old and just loves running. Of course, when I join now I will run completely
at the back of the group, and won’t finish more than half of the fartlek, but it’s
still fun. I invite anyone who wants, to come to Iten and join the Kenyan fartlek.
On Thursday morning, just before 9 am, you can find groups of runners around Iten, waiting to start their fartlek Alternating 1, 2 and 3 minutes fast, with 1-2 min easy in between. There are
different ways of going about this. One option is as follows: 4 x 3/1, 4 x 2/1, 4 x
1/1. So that makes for a 36 min fartlek, starting with 4 sets of 3 min fast, one min
easy. Then 4 sets of 2 min fast, 1 min easy. And finishing with 4 sets of 1 min
fast, 1 min easy. Note that there is no set pause here – in this example, all
recoveries are 1 min easy, but feel free to change that to 2 or 3 min easy if needed.
What I like with this session, is that you cover several paces. You may start with
the 3 min around your half marathon or anaerobic threshold effort, followed by 2
min reps at 10km race effort, and then the 1 min around your 5km race effort.
And you can progress this to longer efforts as well, for example by doing
something like 6-5-4-3-2-1 min fast (in between 1-2 min easy). Another variation
is to constantly change the length, by doing something like this: 3 to 4 sets of 1 –
2 – 3 min fast, with 1 min easy in between and 2 min easy after each set.
Alternating between fast and moderate. This makes for a different style of fartlek.
It works especially well for marathon and half marathon runners. The difference
with the previous examples, is that on most fartleks, the easy parts are really easy.
You just jog for 1 or 2 minutes, and then run fast again. With the fast/moderate
fartlek, there is no easy running in between (except when you decide to add a set
pause). I remember doing this fartlek back in 2013 with the training group of
coach Gabiele Nicola, and his Kenyan top athletes who were preparing for
marathons like Berlin, Chicago and New York. We would run for one hour,
alternating between 1-2 min at a fast but not super fast pace, followed by 1 min at
a moderate pace. Generally, the moderate pace – sometimes referred to as a float
recovery – was close to marathon pace.
To give you a real life example of how I would do this right now: rather than
doing 2 min fast at 3.30 – 3.45/km and 1 min easy at 5.00/km, I would do 2 min
fast at 4.00/km and 1 min easy at 4.30/km. So the fast part may be around half
marathon pace, and the moderate part around marathon pace. It’s actually a heavy
type of fartlek, and it definitely needs some practice before you get the hang of it.
The last type of fartlek that I want to mention, is one where there is a much bigger
change in pace, because you include some longer intervals at a more moderate
pace. One of my favorites is: 10 min tempo, 5 min easy, 5 x 1/1, and then repeat
this whole thing again. So that makes for 50 min of fartlek, including 20 min of
tempo and 10 reps of 1 min on, 1 min off. This way you get a good stimulus at
marathon to half marathon effort, and combine that with some faster intervals at
5km race effort.

Hopefully it’s now clear to you what a fartlek is, and how it can be used. As you can
imagine, there are many more types of fartlek. Just use your creativity and make up
something.
And I know, it’s not easy to be creative, when you have no experience. I have more than
32 years of experience with running, and all these different sessions that I have done,
have given to my runners, or that I have seen others do, are in my head.
For those of you who are interested in a training plan, coach Callum Jones and I wrote 240 weeks of free training plans which can be downloaded from our website. This goes from 20 weeks of preparation for a 5K race (for three different levels of runners, the beginner, the experienced runner and the advanced runner), to 20 weeks of preparation for a marathon.
All split up between a base period and a race specific period.
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