Key takeaways
Fartlek is Swedish for speed play, a continuous run with faster surges and easier running mixed in, with no stops
It was developed by the Swedish coach Gösta Holmér in the 1930s for the national cross-country team
Research on fartlek itself is limited to small studies, so most of its rationale is borrowed from interval training research
Fartlek is the oldest named running workout most people still use, and the most flexible. It is a continuous run in which you play with pace: surge, settle, surge again. No track, no stopwatch required. Here is what it means, where it came from, and how to use it.
Fartlek meaning
Fartlek is Swedish for "speed play": fart means speed and lek means play. Two features define it:
- It is continuous. The recoveries are easier running, not standing or walking rest.
- The structure is loose. Effort changes by time, distance, terrain or feel.
That makes a fartlek a cross between a steady run and an interval session. Because the "rest" is still running, a fartlek accumulates a lot of time at moderate-to-hard heart rates without the mental load of reps on a track.
Where fartlek came from
Fartlek was developed by Gösta Holmér (1891 to 1983), a Swedish decathlete who won bronze at the 1912 Olympics and then became a national instructor for the Swedish Athletics Federation from 1925. During the 1930s, coaching Sweden's cross-country runners, he created a way of training that mixed faster-than-race-pace running with steady endurance work in the same session, run over forest trails rather than the track. Holmér wrote several books on athletics training, but most English accounts of his method are second-hand.
The fartlek run: structured vs unstructured
Unstructured fartlek is Holmér's original spirit. You run by feel and terrain: push to the next tree, jog to the hill, surge up it, float across the flat. It teaches pace awareness and keeps hard running playful.
Structured fartlek sets the surges by time or distance, such as 8 × 2 minutes with 1 minute easy. It looks like an interval session, but the recovery is a steady float rather than a stop, so the average intensity is higher.
| Unstructured | Structured | |
|---|---|---|
| Best for | Beginners, trail runners, base phase, mental freshness | Race preparation, tracking progress |
| Control | Feel and terrain | Watch: time, distance or heart rate |
| Risk | Drifting too easy or too hard | Turning it into a race |
Fartlek training examples
Each session starts with 10 to 15 minutes of easy running and ends with 5 to 10 minutes easy. "Float" means a steady jog that is still running, not walking.
| Session | Warm-up | Surges | Pace / HR / RPE | Recovery |
|---|---|---|---|---|
| Beginner minutes | 10 to 15 min easy | 8 to 10 × 1 min | Comfortably hard, about 10 km effort; RPE 6 to 7 | 1 to 2 min easy float |
| Pyramid | 15 min easy | 1-2-3-4-3-2-1 min | 3 to 4 min parts near threshold, 1 to 2 min parts near 5 km effort; RPE 7 to 8 | Equal time easy float |
| Mona fartlek | 15 min easy | 2 × 90 s, 4 × 60 s, 4 × 30 s, 4 × 15 s (20 min total) | 90 s at about 5 km effort, getting faster as reps shorten; RPE 8 to 9 | Equal time float, steady not jogging |
| Long-surge fartlek | 15 min easy | 4 to 5 × 5 min | Threshold effort, about one-hour race pace; 88 to 92% of max HR; RPE 7 | 2 min float |
| Landmark fartlek | 10 min easy | 10 to 20 surges to lamp posts, trees or corners | Varies, mostly 5 to 10 km effort; RPE 6 to 8 | Jog until ready, still running |
| Hill fartlek | 15 min easy | Surge every uphill on a rolling route | Strong uphill, relaxed downhill; RPE 7 to 8 | Flats and descents easy |
The Mona fartlek comes from the Australian marathoner Steve Moneghetti and his coach Chris Wardlaw. It totals 10 minutes of surges and 10 minutes of float, and the float is the hard part: it should be a steady run, not a shuffle. It is a good monthly benchmark, because you can compare total distance covered in the 20 minutes.
Set the effort for the faster parts from a recent race using the VO2max running calculator, or by heart rate with the heart rate zone calculator.
What the research says
The honest answer is that fartlek itself is thinly researched. Published trials are mostly small, short and in lower-profile journals. In one pilot study, Gautam, Pal and Rakheja compared six weeks of fartlek with high-intensity interval training in 15 national volleyball players: both groups improved power versus controls, but the interval group improved VO2max more than the fartlek group. That is a tiny sample in a non-running sport, so it settles little.
Most of the rationale for fartlek is borrowed from interval research (see HIIT vs steady cardio). In Helgerud and colleagues' 2007 study, intervals at 90 to 95% of maximum heart rate raised VO2max where steady running at lower intensity did not (see the Norwegian 4×4). A fartlek with long, hard surges and short floats works in that territory; a fartlek of short, gentle surges works closer to a steady aerobic run. In other words, a fartlek is only as specific as the efforts you put into it.
How fartlek fits your week
- Base phase: one unstructured or beginner fartlek a week alongside easy running is a gentle introduction to speed, especially for those following 80/20 training.
- Race phase: swap in longer surges at threshold (a looser version of a tempo run) or harder, shorter ones similar to VO2max workouts.
- Strength: on rolling terrain, a hill fartlek overlaps with hill repeats and complements strength training for runners.
- Recovery: count a hard fartlek as a quality day; don't follow it with another hard session. Runners on the Norwegian singles method can use a controlled fartlek as an occasional replacement for a sub-threshold day, keeping surges below threshold.
If your watch shows rising resting heart rate or falling HRV, ease back (recovery signals). More running guides are on the running page.
Safety: if you have a heart condition, high blood pressure, or have been inactive, get medical advice before adding hard surges to your running.
Frequently asked questions
What does fartlek mean?
Fartlek is Swedish for speed play, from fart (speed) and lek (play). It describes a continuous run in which you mix faster surges with easier running, without stopping between efforts.
What is a fartlek run?
A run, usually 30 to 60 minutes including warm-up, where you alternate faster and slower running by time, distance, landmarks or feel. The easy parts are still running, not standing rest, which is the main difference from track intervals.
What are some fartlek training examples?
Classic examples are 10 × 1 minute fast and 1 minute easy, a pyramid of 1-2-3-2-1 minutes with equal easy running, the 20-minute Mona fartlek, and an unstructured run surging to landmarks such as lamp posts or the top of hills.
Is fartlek good for beginners?
Yes, as long as the fast parts are controlled. Short surges of 20 to 60 seconds at a comfortably hard effort, with plenty of easy running between, are a gentle first step into faster training.
Sources
- Olympedia. Gösta Holmér, athlete biography (Olympic results, Swedish Athletics Federation role, development of fartlek).
- Gautam N, Pal S, Rakheja H. Comparative study of the effectiveness of fartlek training and high-intensity interval training on VO2max and power on volleyball players: a pilot study. J Clin Diagn Res, 2024.
- Helgerud J, et al. Aerobic high-intensity intervals improve VO2max more than moderate training. Med Sci Sports Exerc, 2007.
- The Long Run Australia. Session #1: Mona Fartlek (Moneghetti and Wardlaw's session; no formal publication by its originators).