Fartlek — Speed Play

By Runsense · Reviewed by Raphael Crawford-Marks, Founder · Last reviewed June 9, 2026

"Fartlek" is Swedish for "speed play," and that's exactly what it is: bursts of faster running woven into an easy run, done by feel rather than by a stopwatch. It's the most relaxed, flexible way to add some speed — and a friendly on-ramp for runners who find the track intimidating. This is general training guidance.

What it is

A fartlek alternates faster surges with easy running, but unlike formal intervals there's no prescribed structure. You pick the efforts as you go: surge to the next lamppost, push for the length of a song, or just run hard until you feel like easing off, then jog easy until you're ready again. The duration and intensity of each burst are loose and up to you — that's the "play."

Why it works

Fartlek teaches you to change gears and run faster while staying relaxed, without the mental load of hitting exact splits. It's a gentle bridge between easy running and structured speedwork — enough stimulus to start developing speed and the ability to surge, but flexible enough to fit any terrain or mood. It's also genuinely fun, which makes it a great way to break up a training block or reintroduce intensity after easy weeks.

How to do one

Keep it simple and playful:

Where it fits

Fartlek shines early in a training block as a low-pressure transition into faster work, or any time you want a quality day without the rigidity of a track session. It's especially good for newer runners building confidence with speed, and for practicing the surges and pace changes that real races (with their hills, turns, and competitors) demand.

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