Last updated: 3 October 2026
Reviewed by Jordan Morley, FA Level 2 Football Coach
Fartlek (Swedish for ‘speed play’) is a flexible, unstructured form of interval training where the runner varies pace spontaneously — surging to a landmark, easing off, then surging again. Developed in Sweden in the 1930s, it blends continuous and interval training, developing both aerobic and anaerobic systems while keeping training enjoyable and adaptable to terrain and feel. Unlike track intervals, fartlek has no fixed structure, making it mentally refreshing and easy to incorporate into any run.
- Swedish for ‘speed play’
- Unstructured, spontaneous pace variation
- Develops aerobic and anaerobic systems
- Flexible and mentally refreshing
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Fartlek ('speed play' in Swedish) training mixes fast and slow running within a single continuous run, often using landmarks or feel rather than a GPS watch to dictate the changes in pace — its unstructured nature makes it a less precise but more enjoyable and flexible way to build speed and aerobic capacity compared to a strictly measured interval session on a track.
FAQ
How is fartlek training different from interval training?
Interval training uses precisely measured distances or times with set recovery, while fartlek is more free-form, varying pace by feel or landmarks within a continuous run, without strict structure.
Is fartlek training good for beginners?
Yes — its flexible, less rigid structure makes it an approachable introduction to speed work for newer runners who aren't ready for a strictly measured track session.