Fartlek training: sample sessions, paces and where it fits in a plan
Updated October 4, 2026
Fartlek means playing with your pace. Here is how to run it, how fast, and where it fits in your training.
What is fartlek?
The word comes from Swedish and means “speed play”. It is a session in which you alternate surges and slow phases without watching the stopwatch to the second. There are two versions: free fartlek, done by feel, and structured fartlek, with durations set in advance.
What pace for the surges?
Between 85 and 100% of your vVO2max: from threshold pace (85–90%) to vVO2max pace (100%); the shorter the surge, the faster you can go. For a vVO2max of 15 km/h, the fast phases are run at 4:00 – 4:42 per km and the slow phases at base endurance pace, 5:20 – 6:09 per km.
Four sample sessions
| Session | Structure | When |
|---|---|---|
| Free fartlek | 40 min easy run with 6 to 8 surges of 30 s to 2 min, wherever you feel like it | First taste, start of the season |
| Classic | 10 × 1 min fast / 1 min slow, after a 15 min warm-up | Base and build phases |
| Pyramid | 1 – 2 – 3 – 2 – 1 min fast, recovery lasting half as long as the effort | Variety, running by feel |
| Hill repeats | 8 × 30 s uphill, jog back down | Base phase (alternating with fartlek) |
Where does it fit in a plan?
Fartlek is the gateway to speed. In the Runalis plan, it alternates with hill repeats during the base phase, before vVO2max intervals and threshold work take over in the build phase. It comes back in a light version during recovery weeks. The rule stays the same: a single hard session per week for a runner doing three runs a week, never right next to the long run.
Common mistakes
- Running every surge flat out: you will finish the session exhausted, with uneven efforts.
- Cutting the recovery short: it should let you set off again at the same pace.
- Skipping the warm-up: do 15 minutes of easy jogging before the first surge.
Runalis is not medical advice. If you feel pain, stop and see a health professional.
In the app
Fartlek, in the right place in the plan
Runalis alternates hill repeats and fartlek in the base phase, then switches to vVO2max intervals, never putting two hard sessions back to back.
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