It’s fine at first, as you find your 5K time improving a little week by week. Kudos rack up providing just the motivation you need to get out there and run again and again. But, as with all training, there comes a time when you hit a wall.
It’s obvious if you think about it: You’ve put your body under the same stress every week, so now it knows exactly what to expect. But when you’re running against the clock, it’s very frustrating when progress slows.
The solution? You need to vary your sessions by adding interval runs, and one of the most beginner-friendly and fun interval sessions is fartlek running.
This type of running will help you build both speed and endurance simultaneously by varying the pace you use throughout your run. If you’ve got a race booked, it will better prepare you to conserve energy when you need it and accelerate, too.
So whether you’re hoping to impress your run club crush, keep up with your best friend in your upcoming 10K, or just bring the enjoyment back into running, fartlek training will get you there–and we’ll show you how.
Ready to get started on a new running plan? Whether you’re training for a race or just want to get started with running, our free running plans on the Gymshark Training App will guide you through every mile.
What Is A Fartlek Run?
Swedish for ‘speed play,’ a fartlek run is a form of interval training based on feel and inspiration. It mixes slow-paced periods with harder effort and faster running [1].
It’s typically ‘unstructured’–giving the runner complete freedom in terms of the frequency, length, and duration of each interval. There are no rules or set pace, meaning you can adapt the session depending on how you feel. All you need to do is run.
The catch? You don’t get to rest. This is a continuous run. If you need to stop or walk, you’re going too fast.
How Does Fartlek Differ From Other Interval Training?
Typically unstructured (although fartlek runs can also be structured)–you pick the duration of your intervals depending on your environment and how you feel rather than setting a specific duration or distance.
No rest - a fartlek run is a continuous run.
Your top pace will likely not be as fast as other styles of interval running.
Your overall average heart rate is likely higher for a fartlek workout (as you don’t have as much recovery!).
How To Do Fartlek Workouts
Unstructured Fartlek Workout (Aka The Classic Fartlek Run)
As mentioned, a fartlek run is traditionally unstructured, meaning there is no set distance or time for your intervals. Instead, you judge your intervals based on feel.
These types of fartlek runs are divided using landmarks as guides. You might run fast to the upcoming lamppost, jog to the crosswalk, pick up the pace as you run to the tree, but slow things down again as you begin up the hill. Adjust as you go, depending on how you feel and what you see around you.
Unstructured Fartlek Training Example: The Mona Fartlek
Warm-up: 10-minute easy pace run and some dynamic stretches.
Then, a continuous effort run for 20 minutes, matching equal amounts of work time to rest time:
2x90 seconds
4x60 seconds
4x30 seconds
4x15 seconds
Finally, cool down by doing a steady jog for 5-10 minutes and some static stretches.
Structured Fartlek Workout (Aka The Adapted Fartlek Run)
Just because fartleks started unstructured doesn’t mean they must be done that way. They can also be done using set distances and durations, for example:
10 sets of 2 minutes at goal pace followed by 2 minutes at an easy pace
2x800m at goal pace with 90 seconds slower pace, followed by 4x400m at goal pace with a 60-second recovery between intervals.
The pace will still be set by how you feel (rather than a set pace).
Structured Fartlek Training Example: Downward Ladder
Warm-up: 10-minute easy pace run and some dynamic stretches
Then, a continuous effort run for 20 minutes:
5 minute hard run / 1 minute easy run
4 minute hard run / 1 minute easy run
3 minute hard run / 1 minute easy run
2-minute hard run / 1-minute easy run
1-minute hard run / 1-minute easy run
Finally, cool down by doing a steady jog for 5-10 minutes and some static stretches. (Try these 6 stretches every runner should do to avoid injury.)
FAQs
How Long Should A Fartlek Run Be?
Fartlek runs can range from as little as 20 minutes (as the fartlek run examples above do) to 60 minutes or more.
If you’re a beginner, you should start by doing 20-minute fartlek runs. If you’re training for speed over a 5K, keeping your fartlek runs to a maximum of 20 minutes is a good way to increase your pace and aerobic capacity over a short distance.
If your goal is to increase your speed and endurance for longer distances (e.g., a half marathon or marathon), you could work towards 60—to 75-minute fartlek sessions to build endurance and speed simultaneously.
How Many Intervals Should You Do In A Fartlek Run?
This depends on your training level, what you are trying to get out of the session, and your goal. A more endurance-based fartlek might include fewer intervals for longer durations. A fartlek workout focused on speed might include up to 10 intervals of shorter durations.
A 2013 meta-analysis examining 37 studies found that the nine most effective studies used longer intervals lasting between 3 and 5 minutes, suggesting that longer intervals are most effective for improving VO2 max ** [2].
To get the best of both and continually challenge your body, you could alternate interval duration within your fartlek workout or between each workout, combining short, fast intervals with longer, slightly lower ones to build endurance and speed.
What Is A Good Pace For A Fartlek Run?
There is no set pace for a fartlek–instead, you need to be in tune with how your body feels. Your work intervals should feel hard, but not as hard as a regular interval session, as you should still have some gas in the tank to maintain running through your recovery interval.
Aim for your hard effort pace to be a 7 to 9 out of 10 on the RPE scale*, and your recovery to be a 4 to 6 out of 10 effort RPE.
How Often Should I Do Fartlek Runs?
If you’re new to interval training, add fartlek runs into your program once a week. Over time, you can build up to two fartlek sessions a week if you wish.
Due to the intense nature of the sessions, you should perform fartlek runs too often. Even elite endurance keep their high-intensity training to only 20% of their weekly volume, with two high-intensity sessions a week found to produce performance benefits whilst allowing sufficient time for recovery [3]. Always leave at least 24 hours between runs, but up to 72 hours is recommended, particularly for harder sessions [4].
Discover the benefits of lower intensity, zone 2 training, that makes the perfect compliment to your fartlek sessions.
Can You Run A Fartlek Run On A Treadmill?
Sometimes, the weather isn’t on your side, or you finish work late and don’t fancy stepping out in the dark. Luckily, you can still perform fartlek runs on a treadmill.
Listening to music? Speed up during the song's chorus and slow your pace during the verse.
Watching tv? Speed up during the ad break, and slow your pace when the show comes back on.
People watching? Pick up the pace whenever someone new gets on or off a machine near you.
Structured fartleks on the treadmill are a bit more self-explanatory (but unstructured intervals are often a bit more fun and can make the time pass quicker!).
Just be careful when increasing and decreasing the pace on the treadmill. Sometimes, slowing down and speeding up using the buttons can disrupt your pace, so you may prefer to use longer durations for each phase on the treadmill to prevent having to adjust the pace as frequently.
The Benefits Of Fartlek Running
A Good Intro To Intervals: If you’re looking to dip your toe into interval run, fartlek runs are a great place to start, easing you into the demands of faster pace running with the flexibility to tailor your work-to-rest ratios for each interval depending on how you feel.
Improved Speed & Endurance: Switching between periods of low-intensity aerobic and high-intensity anaerobic exercise during a continuous run improves the anaerobic threshold [5]. By becoming more efficient at removing lactic acid from your bloodstream, you can run for longer, at higher intensities.
You’re In Control: With fartlek runs, you decide how much and for how long you want to push yourself. This is great for teaching the mental resilience of knowing when to push yourself (or when to scale back and preserve energy on those days you don’t feel as full of energy, too). Just don’t go
too
easy on yourself. This is an interval session, after all, which should be challenging.
A Taste Of The Race: Races, especially long ones, are rarely run at one consistent pace throughout. Fartlek sessions teach your body to better anticipate a mid-race acceleration to catch up or pass an opponent.
Tips
Use The RPE Scale To Judge Your Pace: Fartlek runs have no set pace, but you still want to make sure you are hitting the right pace on your intervals. This is best done using the RPE scale*, judging how you feel during each interval and adjusting your speed accordingly. Aim for your hard effort pace to be a 7 to 9 out of 10 and your recovery to be a 4 to 6 out of 10 effort.
Don’t Go Too Fast On The Tempos: Following on from the above, if you’ve been doing tempo running for a while, you might be used to going all out during your fast-paced interval as you have time to recover after. Fartlek runs, however, don’t give as much opportunity for rest. Don’t go out as fast on Fartlek runs so that you can continue to run during your rest interval.
Use Your Surroundings: If you can, get outside and use the environment to structure your sessions. This can make the run a lot more enjoyable.
Always Warm Up Properly: Like any form of speedwork, fartlek running carries a higher risk of injury. To help avoid injury, always warm up properly for your session by running at an easy pace for 5 or 10 minutes and performing some dynamic stretches (Try these mobility exercises before your next run).
Give It Time: Having full control of how hard you push and when can take some getting used to! Go out too hard, and you’ll need more rest; go out too slow, and you may not push yourself enough. Over time, you’ll get used to how your body should feel during each interval. This can take time, so bear with it and keep practicing.
Don’t Neglect Recovery: Fartlek runs may be more relaxed in structure, but that doesn’t make them less taxing on the body. Always stick to the 80/20 rule, whereby 80% of your weekly training is zone 2, and only 20% is hard effort work [3]. If possible, leave two or three days between interval runs.
All In All
We all reach a point where we struggle to progress in our training or our motivation is low. Fartlek running might be just what you need to switch up your runs, make things interesting again, and start seeing progress.
Structure your session based on landmarks, city blocks, or even music–the choice is yours–and we know that with consistency, you’ll start to see improvements in your performance and enjoyment.
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*RPE (rate of perceived exertion) scale measures how hard your body is working duration of a given activity based on effort. On a scale of 1 to 10, 1 is no effort (such as sitting down), 2-3 (minimal effort), 4-6 (moderate effort), 7-8 (hard), and 9-10 (threshold to max effort).
** VO2 max is the maximum amount of oxygen your body can use during intense exercise.
References:
Shingala, M. and Shukla, Y. (2019). Effectiveness of Fartlek Training on Cardiorespiratory Fitness and Muscular Endurance in Young Adults: A Randomized Control Trial.
Bacon, A.P., Carter, R.E., Ogle, E.A. and Joyner, M.J. (2013). VO2max Trainability and High-Intensity Interval Training in Humans: A Meta-Analysis.
Stöggl, T.L. and Sperlich, B. (2015). The training intensity distribution among well-trained and elite endurance athletes.
Academy, U.S.S. (2009). Comparison of 5km Running Performance after 24 and 72 hours of Passive Recovery.
Gnanavel, N. (2020). Effect of fartlek training on cardiovascular endurance and speed endurance among college men students.
