Fartlek

10-20-30 Copenhagen

Science-backed VO2max booster

28 min · Fartlek · Speed

Main set: 5 × (30 s @ 30% + 20 s @ 60% + 10 s @ 90%) · 2 min @ 30% · 5 × (30 s @ 30% + 20 s @ 60% + 10 s @ 90%) · 2 min @ 30% · 5 × (30 s @ 30% + 20 s @ 60% + 10 s @ 90%)

Open in Fartlek

About this workout

The 10-20-30 concept was developed by Thomas Gunnarsson and Jens Bangsbo at the University of Copenhagen and published in 2012. Each minute you run 30 seconds slow, 20 seconds at a moderate pace and 10 seconds near your maximum; 5 of those minutes make a block, with 2 minutes of recovery between blocks.

In the original study, recreational runners who did it 3 times a week for 7 weeks, on about half their usual volume, ran 5 km 48 seconds faster and 1500 m 21 seconds faster, and their blood pressure dropped. Fartlek's version runs 3 blocks with easy running between them, like the study's first weeks. The 2012 study.

The workout

Block	What to run	Cue
Warm-up	4 min @ 40% + 2 min @ 50% + 30 s @ 70% + 1 min rest	Easy start, build gradual
10-20-30 Set 1	5 × (30 s @ 30% + 20 s @ 60% + 10 s @ 90%)	Easy-moderate-fast
Recovery	2 min @ 30%	Walk or easy jog
10-20-30 Set 2	5 × (30 s @ 30% + 20 s @ 60% + 10 s @ 90%)	Same rhythm, stay smooth
Recovery	2 min @ 30%	Reset before final set
10-20-30 Set 3	5 × (30 s @ 30% + 20 s @ 60% + 10 s @ 90%)	Finish strong
Cool-down	2 min @ 30%	Ease down, breathe

How each effort should feel

Efforts are a percentage of your all-out effort, set by feel (RPE), not by pace. From Fartlek's effort guide:

30% Very easy. Walking pace or the gentlest jog.
40% Easy. Relaxed jog, easy to chat.
50% Comfortable. Easy running, full sentences.
60% Steady. Still chatty, breathing deeper.
70% Moderately hard. Short sentences only.
90% Very hard. A word or two, tops.

Pete's tip

Jog easy 30s, pick up 20s, then sprint 10s. Rest between sets. Proven to boost fitness fast. Stay relaxed on the easy, explode on the 10s.

Pete, Fartlek's AI coach

What it trains

Speed. Improve your pace and explosiveness.