Run a little quicker to that tree. Ease off until your breathing settles. Pick another landmark. That, in spirit, is fartlek: a run with changes of pace and room for a bit of play.
It does not need perfect lap splits, a track booking or a spreadsheet. It does need some thought about effort, because an informal workout can still become a very hard one.
The highlights
- Fartlek mixes faster and easier running; it can be free-form or organised by time.
- The playful format does not mean unlimited surges or racing every lamp-post.
- Use it instead of another quality session when it contains substantial harder running.
At a glance
Main purpose: Introduce varied pace, practise effort judgement and add playful structure without needing a track.
Effort: Varies by design; the examples use controlled pickups rather than all-out efforts.
Where it fits: Can replace a structured quality workout; very gentle versions can introduce pace changes.
When in a training cycle: Useful when moving from easy-running consistency towards more specific faster work.
The examples below are original coaching illustrations, not protocols tested in the cited studies or personalised prescriptions. Effort numbers use an informal 0–10 guide, not a laboratory zone conversion. Choose an option within your current capacity; you never have to progress because a calendar says so.
What is fartlek?
Fartlek is commonly translated from Swedish as speed play. In coaching use, it means varying pace within a run, often using time, landmarks, terrain or how you feel rather than fixed track distances.[1]
Some versions are spontaneous: gently accelerate to the next clear landmark, then return to easy running. Others are structured: six one-minute pickups with easy running between them. There is overlap with interval training; the distinction is often flexibility and setting rather than a completely different biological process.
You can make a fartlek session gentle, demanding or somewhere between. Its name alone does not tell you how much recovery it needs.
What is it used for?
Fartlek offers a way to practise changing gears without the pressure of comparing every repetition against a familiar track split. It can be useful when returning to faster running after a period of easy consistency, or when you simply prefer a less rigid session.
It also creates opportunities to learn your own effort. A pickup into a headwind may be slower than the last one while feeling equally demanding. That is not a failed repetition; it is information about the conditions.
For group running, the format can be inclusive when each person controls her own effort and everyone agrees where to regroup. It becomes less inclusive when the “play” turns into being repeatedly chased by the quickest runner.
What the sources support
Coach Greg McMillan recommends fartlek as a transition towards faster, race-specific training. One of his aims is to:
“learn your effort levels and how to adjust the workout based on how you feel”
— Greg McMillan, The Lost Art of the Fartlek.[1:1]
That is first-party coaching guidance, not a controlled trial demonstrating that fartlek is superior. We use it for the practical idea of an effort-led transition, not as proof that the method prevents injury.
The broader interval literature supports a more general point: changing the intensity and duration of the faster work and its recoveries changes the training stimulus.[2] It does not establish a special benefit from choosing trees instead of a stopwatch.
So the case for fartlek here is a combination of credible training principles and practical flexibility. Enjoyment and preference can help you choose a format without pretending that every coaching convention has its own large scientific trial.
How hard should the faster parts be?
For your first experiments, think brisk and controlled rather than sprinting. You should finish a pickup able to ease smoothly back into easy running. If the only possible next action is stopping with your hands on your knees, the session is probably harder than intended.
Keep the easier sections genuinely easy. There is no requirement to run them at a particular pace. Walk where appropriate, especially if you are learning how to judge effort.
You can also decide before leaving that the whole outing will remain gentle, with only a few small changes in rhythm. Be honest afterwards: ten long, hard surges make a quality session even when none were timed.
Two examples with plenty of room to breathe
A gentle first taste: 25 minutes. Begin with 8 easy minutes. Complete 4 rounds of 20 seconds a little quicker followed by 100 seconds easy. Finish with 9 easy minutes. The four two-minute rounds total 8 minutes, so the whole outing is 25 minutes. The final recovery is included deliberately.
A structured fartlek for an established runner: 37 minutes. Run easily for 10 minutes, complete 6 rounds of 1 minute of controlled faster running and 2 minutes easy, then finish with 9 easy minutes. That is 10 + 18 + 9 = 37 minutes, including easy running after the final pickup.
These are alternatives. The faster parts do not have to be identical in pace when the ground or conditions differ. The aim is broadly comparable control, not winning a stopwatch contest.
For a free-form version, keep the same modest overall time and choose a few safe landmarks. Do not quietly double the amount of faster running because the route offers lots of attractive targets.
Where it fits in the week
A meaningful fartlek workout can use the same weekly slot as intervals, hills or tempo running. On a three-run schedule, that might mean Tuesday easy, Thursday fartlek and Sunday a familiar easy longer run.
If you are new to running, keep the week easy and use run–walk first. The NHS beginner programme’s combination of gradual running and rest days is a useful starting structure.[3] A gentler pickup session can come later when ordinary outings feel comfortable.
A hard parkrun is not an easy extra. Nor is a hilly social run automatically gentle. Count what you actually did, not only the heading in the diary.
Where it fits across a training cycle
Fartlek can bridge an easy-running phase and more specific race preparation. It can also replace a rigid session when conditions make pace targets unhelpful, provided the route itself remains safe.
In a lighter week, reduce the number or intensity of pickups. Near a race, keep any faster running small and familiar rather than trying a new, exhausting version. “Unstructured” should mean adaptable, not unplanned overload.
Common questions
Do I need a running watch? No. Landmarks can work well where the route is clear and safe. A watch is useful when you prefer a predictable time limit, but it is not what makes the session valid.
Can I do fartlek on hills? Yes, but a steep climb can make the effort much harder. Avoid chasing flat-ground speed uphill or accelerating into an unsafe descent. Choose terrain that helps you keep the intended control.
Is it less serious than intervals? No. It is simply another format. A thoughtful, repeatable workout is more useful than a serious-looking session that does not fit you.
Give the faster parts a purpose and the easy parts some kindness. That is plenty of structure for a little play.
Keep exploring
- Interval training: faster running, sensible recoveries and no need to sprint
- Strides: a small dose of quicker running, not a secret sprint workout
- Run–walk training: a proper running strategy, not a consolation prize
Sources and further reading
This guide is general education for adults, not an individual medical, rehabilitation or pregnancy/postpartum training plan. Seek qualified advice when symptoms, a health condition or a return from injury make exercise decisions uncertain.
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McMillan G (undated guidance; checked 3 October 2026). The Lost Art of the Fartlek. McMillan Running. ↩︎ ↩︎
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Buchheit M, Laursen PB (2013). High-intensity interval training, solutions to the programming puzzle: Part I: cardiopulmonary emphasis. Sports Medicine. DOI:
10.1007/s40279-013-0029-x. ↩︎ -
NHS (undated guidance; checked 3 October 2026). Get running with Couch to 5K. NHS. ↩︎