How to Use Fartlek Training to Improve Your Running


Running regularly yields lots of physical and psychological benefits. It also helps you strive towards an end goal, usually one or a series of races throughout your running calendar. But, what happens once you reach a plateau and your running isn’t getting any faster or your endurance has remained roughly the same? This is where fartlek running could be that extra ingredient to throw into the mix and spice up your training.

Fartlek running is a form of speed training that has been employed by professional and amateur runners alike to add some fun and less structured workouts into your run training. It involves mixing up your pace so your speed and endurance will benefit while refreshing your training routine will kick up your motivation.

In this article, we’ll review what fartlek training is, how you can use it as part of a training program, and why fartleks can make you a better runner overall.

What is a Fartlek?

The term ‘fartlek’ is originally from Swedish and means ‘speed play.’ This should give you a good idea of what the overall aim of these runs can be! In short, coaches and scientists began to experiment with less structured alternations of speed/pace a few decades ago, adding variety to training by using these fartlek runs. It’s Swedish running coach Gösta Holmér who is credited with spreading the idea in the 1930s.

While Holmér was coaching the Swedish cross-country team, he added faster-than-race-pace intervals to motivate them and stimulate their physical and psychological adaptations. Since then, fartleks have been used successfully to boost performance in track workouts as well as with road or trail runners. They can take many forms, but the main concept is that they are unstructured, fast bursts of running.

You can add fartleks into a long run, interspersing random fast-paced runs while doing your continuous running at a comfortable space. If running outside, the idea is that you will pick random landmarks to use as your start and endpoints, for example, trees or park benches. This is what randomizes and ads fun to the session. Indoors, fartleks on a treadmill could just mean you up your speed at random times, e.g. when the timer hits three times the number “3” (13:33) or when you see commercials on TV if you’re watching something while cruising at your normal running pace.

Why is Fartlek Running Beneficial?

There are several reasons that coaches and runners enjoy fartlek training as a form of mixing up workouts leading to faster running. They leave the runner in control, letting you choose if you’re going for maximum effort or 70-80%, how long for, and how many times during a session. This is a great challenge for runners, but also a good psychological exercise for those who need to develop confidence. Fartleks are also mostly associated with bringing a bit more fun into workouts.

Putting you in control

The fact that these sort of workouts put you in control of the pace, frequency and number of intervals performed is an important element of training psychology. Runners with a coach will usually depend on their structured running plan to train, which can lead to less self-reliance and confidence on race day.

Moreover, by having complete control of your ‘speed play,’ you get to more finely tune your relationship with your body when it comes to running. This might sound woolly, but often, it’s all too easy to just follow a training plan blindly and end up overtraining or risking injury. Including an exercise session like fartleks into your training plan reminds you to listen to your body’s signals and adapt your workouts.

Finally, in a race situation, when opponents are threatening to overtake, having done fartleks in training will give you the ammunition you need to step on the accelerator at that random point in time and prevent being left behind. Psychologically, this makes a huge difference in a competitive environment.

Mixing up pace without the pressure of intervals

Fartleks are a form of interval training. For some athletes, especially endurance runners, speed work or even the idea of interval training is not that appealing at all. For them, fartleks can be an ideal way to include some faster paced workouts in a training plan without the full-on pressure of scheduled intervals on a track, for example.

As you run at race pace or just below, adding a few short sharp bursts of faster running will give your body the adaptations from pushing harder without being set in a time pattern. In time, this added speed training will improve your overall race performance. All without the dreaded “interval session”!

Mimicking “real life”

The other great benefit of running fartleks is that they are the closest you will get to a race situation while in training. Think about it: in the “real world,” you will not be running to a specific pace or heart rate, but you will be swept away by the adrenaline of all the other runners around you. And, even if you’re not going at maximum effort levels, you will be likely to go faster than usual, especially at the start of the race.

Fast forward a few miles and you’ll be settling into your normal rhythm, planning to finish at a desired pace. What happens when someone is suddenly about to overtake you before a tricky, technical section of trail? You’ll want to step up your speed and protect your position – the ideal scenario for an unscheduled interval!

The same happens in the end of races when you’re going for that sprint finish. Having performed a few fartlek sessions as part of your training plan, you will know ahead of time that not only you can sustain that type of effort, but you will also have the speed and the muscle memory to pull it off when needed.

How Can You Include Fartleks in Your Training Schedule?

Just like any type of speed workout, fartleks need to be scheduled into a broader workout plan ahead of races or goal events in your running calendar. Here are some guidelines around how to include fartlek workouts when you plan your runs:

  • Trust your feelings. The most effective way to run fartleks is not on distance or time, but on feel. Think of running on a 7-10 out 10 scale when you’re going at full effort, and then on around 5 out of 10 effort level when you’re recovering.
  • Keep running. One of the key differences between fartleks and intervals is that fartlek workouts include continuous running. This means you never really stop altogether or walk after the end of your fartlek effort. Instead, keep running at a steady pace.
  • Use visual cues. One of the reasons trail runners love fartleks is that you can add them into your longer runs out in nature and they make your session fun and let you interact with your environment more. Run hard when you see a tree, a bush, or a big rock. Go slower when you find the next one (or another, more challenging element to find on a trail!). In a city, you could run from one street light to the next, or in between lamp posts, street blocks, etc.
  • Don’t neglect recovery. Even though when you run fartleks you can come away feeling more relaxed after your workout, this doesn’t mean that you don’t need to recover appropriately after completing a fartlek session. Traditional interval training is based on high-intensity efforts and will leave you feeling drained, so you will naturally want a slower run or a rest day the next day. After fartleks, remember that your body has gone through the same sort of pressures running at a faster pace and alternating between sprinting and recovering. Therefore, stretching and recovery are just as important after these sessions.
  • Adapt to your race and personal goals. When you set out to do your fartlek workouts, try to adapt them to the end goal, i.e. the race you’re training for. For example, if your target race is a fast 5k, then focus on intense running for 30-60 seconds during your fartlek session as you will need short bursts of speed on race day. If, however, you’re planning to run an ultramarathon, run your fartleks with longer efforts of even up to 20-30 minutes, followed by slow running to recover.

3 Sample Fartlek Workouts

Because this workout method is all about spontaneity and using random cues to do your intervals, you don’t need to consider too many rules for running fartleks. However, you can use some sample workouts to get you started.

Classic timed fartlek

A typical workout session including fartlek can be structured as follows:

– 10-15 minutes warm-up (include some running drills to focus on your form)

– 1 minute on, 2 minutes off (fast pace vs. recovery pace) – repeat 5 times

– 2 minutes on, 2 minutes off – repeat 3 times

– 10 minutes cool-down.

Remember that the timings don’t have to be 100% accurate, you’re looking for a fluid running pace and mixing in faster efforts as and when you find some cues. Don’t focus on your watch too much!

Treadmill fartlek

Stuck inside? Watch a favorite program on television and start running at your medium effort pace (after you’ve done your warm-up, as usual). When the commercial breaks start, up your speed and go for intense efforts until the end of each break. Recover during the regular part of the program. 

If you find this too easy as there is too much time in between the breaks, alternate between faster efforts and recovery periods when you see a particular character on the screen. 

Another fun way to run fartleks on a treadmill is to sync to your music: go faster on the chorus, slow down afterwards. The possibilities are endless!

Marathon fartlek

Whether you’re training for a marathon or not, this is a good session with longer distances used. Do your regular warm-up, then follow with 4 km run at your marathon effort, then 1 km steady. Repeat this 4 or 5 times. Finish with your normal cool-down.

Fartlek FAQ

How fast should I run a fartlek?

Because these are unstructured workouts where the harder effort blends in with the recovery at various times and for various periods of time within your session, there is no set speed you should be going at. In terms of effort, we advise it to be somewhere at 7-10 out of 10, keeping in mind that you should keep running continuously throughout your session.

Does fartlek training improve speed?

Any type of speed training will contribute to developing your muscular strength and cardiovascular endurance, enabling you to become faster over time. There are many speed workouts you can do to address your pace, and we have covered our top tips in a separate article here. Fartleks are one of these, with the added benefit of variety and a continuous running requirement, which makes them one of your many tools that you should be using in your training regime. 

How long should a fartlek be?

Fartleks can cover any length and time, but it’s best to work on distances that are most adapted to the race you are training for. So, if you’re training for shorter distances, look at doing quick, sharp intervals with your fartleks. You can even do some track running and measure out 100m, up to 400m at a time. If, however, you are aiming to run 100 miles, do 20-minute fartleks interspersed with medium effort running.

How many times a week should you do run fartleks?

When putting together a training plan, we recommend doing 1-2 speed sessions a week, depending on time and your fitness levels. You should also consider periodization, i.e. creating higher-intensity, higher-volume training weeks and then recovery weeks in between them. Check out our guide to trail marathon training here to get an idea of how to structure a full workout plan. 

What is the difference between tempo runs, intervals and fartlek?

These terms are often used interchangeably, so they’ve lost their meaning a little bit! An experienced runner will probably speak about speed workouts more often than labeling them in any other way. However, here’s a quick breakdown:

  • Tempo sessions are runs you do at your desired race pace. This might mean your whole run is at that pace (like a time trial, e.g. a 10-km run when you’re preparing for a 10k race). Or, you could have a warm-up, followed by a 5k tempo effort, followed by a cool-down. You can also have several tempo efforts within the same session (which makes the session a little like an interval training one… or a fartlek, if you do your tempos at random times!)
  • Interval training sessions are structured runs which include specific periods of time at high intensity. These can be short intervals, e.g. 30 seconds or 200m at top speed, or can become longer for those training for longer races (20-minute intervals with 5-minute recovery periods, for example). If you run 5k in 20 minutes, you could also say that’s your 5k tempo session!
  • Fartlek workouts are speed sessions where, after your warm-up, you pick random periods of faster efforts, interspersed with running at medium effort. You never stop to rest and your faster efforts can vary in length and/or distance covered, frequency etc. Fartleks are like intervals, but without a very set schedule.

Running Fartleks to Get Faster

Thanks to their versatility and added fun factor, fartlek sessions have become a popular way to add speed to your workouts without feeling too much pressure or having to always keep your eyes on your watch. While they can be a challenging type of workout to do if you don’t have the mental inclination to push yourself for hard efforts, they are a great way to mimic real-life race environments and to include your surroundings in your run, too. Besides, any type of speed work will contribute to make you a better, stronger runner, so give fartleks a shot next time you’re off for your regular intervals!

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