Your In-depth Guide to Fartlek Training

A long-time favourite of amateur and professional runners alike, fartlek training dates back to the 1930s, when Swedish fitness coach Gösta Holmér invented it as an innovative, easily accessible way to combine speed and endurance training in a single session.

Fartlek has a rich history in long-distance running for a reason: it’s one of the most effective ways to improve fitness and conditioning, and should be a staple in any endurance athlete’s training programme.

What is fartlek training?

Literally translating as ‘speed play’, fartlek training involves completing a single continuous run with varying tempos: periods of fast running are mixed with jogging or moderate-paced strides (often in an unstructured fashion) so you are continually moving.

Read on to find out more about how fartlek varies from other running training modes, learn the best way to complete fartlek sessions, and discover why it’s such a brilliant training method that could help you clock up your best-ever times.

What is the difference between fartlek, interval, and tempo training?

If you’ve ever followed any form of running training programme, you’ll be aware that there are several different methods for boosting your speed and endurance – all seemingly very similar.

So, how does a ‘tempo run’ differ from fartlek training? How does ‘interval training’ compare? And what’s the point of each type?

Fartlek training

Aside from helping you boost your anaerobic and aerobic fitness, the real beauty of fartlek training lies in its fluidity and flexibility. The idea is to mix times, paces, and distances to create an interesting, varied running session; the more unstructured and random, the better.

The main thing to remember with fartlek training is that there are no rules: as long as you’re continuously moving and switching up the pace, you’ll feel the benefit.

Interval runs

Interval runs are where you really focus on that top-end speed.

An ideal way to improve your VO2 max and running form, these sessions involve short, intense efforts at near-max pace, followed by a rest period where you either stop still, walk, or jog at a very slow tempo to allow you to recover almost fully before going again.

How you format these sessions is entirely up to you: you can run for time, or distance. For example, you could run max-out for two minutes, then walk for three. Or, on a running track, you could sprint for one 400m lap, then walk a lap to recover.

However, unlike fartlek training, where distances and times are unstructured and can change as your run progresses, interval runs follow a set format throughout. So once you’ve set your rep time or distance, and the recovery, you’ll do a set number of those to complete the workout. The distances or rep times won’t vary.

You can make the intervals and rest periods as long or as short as you like, but the key to getting the most out of these intense workouts is to allow enough recovery time so you can blast out each rep.

For a full breakdown, check out our interval training guide.

Tempo runs

If fartlek training and interval runs are all about variety, then tempo runs are all about consistency.

These sessions are where you grind out the miles at a set pace, aiming to stay around 6-8/10 on the rate of perceived exertion (RPE) scale for up to an hour (though most sessions last 20-40 minutes).

As well as helping you improve your pace awareness, tempo runs are a simple way to enhance your lactate threshold, learn to maintain your concentration, and simulate endurance races.

Because these sessions are all about maintaining a consistent, solid pace, it’s important to understand how to set that speed: fast enough to provide endurance and conditioning benefits, but steady enough that you can sustain it for a long time.

For most people, this pace will sit somewhere between 10k and half-marathon pace. A good way to calculate the correct tempo is to run at about 25-30 seconds per mile slower than your 5k race pace, or 15-20 seconds per mile slower than your 10k race pace. For most runners, this will equate to around 80-85% of their maximum heart rate.

Use the quick guide below to compare fartlek training, interval training, and tempo runs.

The benefits of Fartlek training

Now you know your tempo from your fartlek, it’s time to find out why the latter is such a brilliant training mode for runners of all levels.

There are multiple physiological benefits

Fartlek runs improve both your aerobic and anaerobic systems by challenging your heart, lungs, and muscles at varied intensities. This boosts your cardiovascular efficiency, improves speed endurance, and helps you run longer distances without getting tired.

Switching between low-intensity aerobic and high-intensity running also helps your body become more efficient at removing lactic acid from your bloodstream, meaning that, over time, you can run farther at a higher speed.

It’s a fun way to include high-intensity running

Studies have shown that you don’t need to run all of your miles at full intensity to reap the rewards. In fact, the ideal split is about 80% at lower intensity and 20% at max effort.

Fartlek training is a fun way to hit that 20% (and, because of its flexibility, you can also use it for the lower-intensity 80%, too).

It adds variety to running sessions

If you find yourself continually plodding the same running route at a monotonous pace, adding some fartlek training to your sessions will add variety and new challenges to your programme.

It’s especially fun when done in groups, with a nominated leader choosing at random where the rest of the group goes, and at what pace.

It helps with race simulation

Because fartlek training includes continuous movement with frequent pace changes, it closely mirrors the pace surges, slowdowns, and fatigue experienced in real races. It’ll train you to be reactive and change speed while tired, preparing your body and mind for the demands of a race.

It boosts intuition and mental resilience

Fartlek training encourages running by “feel” rather than numbers, teaching you how to tune into your body and adjust your effort intuitively. This will help build your mental toughness, improve pacing awareness, and reduce your reliance on GPS or biometric data from your watch.

It’s accessible

You don’t need to be a member of a running club and you don’t need a prescribed running programme to try fartlek training. You can simply put on a pair of shoes, head out into your neighbourhood, local park, or the countryside, and run however you want to. This means it’s an accessible training mode for all runners: from total novices experimenting with endurance and speedwork for the first time, through to advanced athletes looking to knock minutes off their marathon PB.

You don’t need any special equipment

Not even a stopwatch or a smart watch!

The only equipment to consider is appropriate running clothing and footwear, especially if you’re running in the countryside and off-road. Invest in a pair of trail running shoes or specialist running shoes to ensure maximum ankle and foot support and reduce the risk of painful slips on mud and grass.

Be mindful of its limitations

While fartlek training offers many benefits, it also has some limitations. Specifically, its random nature makes it nearly impossible to measure progress in terms of distance, speed, and recovery times. That said, the more you do it, the more you’ll notice your general fitness improves.

How to incorporate fartlek runs into your training

Because there are no set rules, you can use fartlek sessions however you want to help you meet your running targets, whether your goal is to smash your next 5k or simply have fun while exercising.

However, here are some top tips for getting the most out of this valuable training tool.

Use fartlek training as often as you like

Because you’re in total control of the intensity of each fartlek session, you don’t need to use this method sparingly. If you adjust your effort to match your current fatigue levels to avoid overloading your body, you can add these to your running schedule on a regular basis.

Focus on feel by using RPE

Use the RPE scale to decide whether to up the pace or back off a little, rather than relying on the numbers on your watch.

Imagine that RPE 1 means that you’re so relaxed you could fall asleep, and RPE 10 means you physically couldn’t take one more step. Your running efforts should be ranked at around 7-9/10, while your recovery spells should bring that down to around 4-6/10.

Experiment with ‘float’ recoveries

While you certainly might not feel like you’re ‘floating’ when your legs are heavy and your heart is pounding, this specific recovery technique can help you take fartlek sessions to the next level.

‘Float recoveries’ are when you incorporate periods of faster-than-normal recovery running – usually at a moderate pace – between high-intensity efforts. Because this ups the overall intensity of the workout, you might need to shorten the length or time of your reps.

Don’t get bogged down in the data

While some long-distance runners enjoy logging every training distance and time, the random nature of fartlek runs means there doesn’t need to be an intense focus on recording every metric of these sessions. But it really depends on your personal taste and what motivates you.

Fartlek run training examples to add to your programme

Now it’s time to lace up your trainers and get running!

You could run at a fast pace for one minute, then slow down and run for three minutes at a slower tempo.

Then, you could do mile or half-mile efforts at a quicker pace, followed by an easy half-mile to get your breath back.

And, if you don’t feel like it, you don’t even have to set yourself a target: simply run at a fast pace for as long as you want, then drop the tempo down until you feel like speeding up again.

You’re totally in control – fartlek training is as much an exercise in intuition as it is endurance. But it's always helpful to have some ideas to work from, so here are three specific fartlek run sessions you can try today.

Example 1: The 'free' fartlek

Once you’ve warmed up, it’s time to see where the flow takes you by using the physical environment around you. Try:

• Running from one lamppost to the next, then jogging between the next two.
• Running until you get to the church, then jogging to the supermarket. Then pick two more landmarks to alternate your reps between.
• Running until you see someone walking a dog, then jog until you see another one.
• Running for one song on your playlist, then jogging for one more.
• Picking two car colours: speed up every time a car of one colour goes past, and slow down every time a vehicle of the other colour drives by.

Continue alternating between higher-intensity running and a recovery pace for at least 15 minutes, varying the pace as you see fit. Gradually increase the time you run as you get fitter – aim to add an extra five minutes or so every few weeks.

You can also imitate this training method on a treadmill: simply set the speed to ‘random’ and react as the treadmill accelerates and decelerates.

Example 2: Time-based fartlek

While we’d always encourage you to use ‘free’ fartlek runs for their multiple benefits, you can also create much more structured sessions using prescribed times or distances.

The most famous version of time-based fartlek is called ‘Mona’. Named after four-time Olympian Steve Moneghetti, it’s a high-intensity session made up of 14 hard reps, with the same amount of time spent at a slightly slower pace.

This is how to structure it:

Warm-up.

• 2 × 90 secs hard runs, with 90 secs float between.
• 4 × 60 secs hard runs, with 60 secs float between.
• 4 × 30 secs hard runs, with 30 secs float between.
• 4 × 15 secs hard runs, with 15 secs float between.
• Cool-down.

Example 3: Goal-pace fartlek

Ideal if you’re chasing down a specific race target, goal-pace fartlek runs follow the continuous run format, but with a more defined pace structure to simulate race conditions.

For example, if you’re prepping for a 10k race, add the following session to your programme once a week for a couple of months:

• 15-minute warm-up.
• 6 x 3 minutes at 10k race effort, with 2 minutes easy running between.
• 15-minute cool-down.

And if you’ve got your eyes set on a marathon PB, try this:

• 15-minute warm-up.
• 6-8 x 3 minutes at 10-15 sec/km faster than marathon pace, with 2 minutes easy running between.
• 15-minute cool-down.

It’s time to try fartlek training

Fartlek training is a flexible, fun, and effective way to boost both your speed and endurance, making it perfect for hitting the high-intensity 20% in the 80/20 training method.

Mixing fast bursts of speed with easy running will improve your aerobic and anaerobic fitness, mental resilience, and pace awareness, while keeping the monotony of steady tempo running at bay.

Accessible anywhere and suitable for all levels, fartlek training will add variety to your runs and take the pressure off times, distances and data – so grab your shoes, give it a go, and have fun!