Norwegian 4×4,
done right.
Four intervals of four minutes above 85% of max heart rate, three minutes of recovery between each. It’s the most-studied protocol for raising VO₂max — the fitness marker most tightly linked to how long you live.
How to do the Norwegian 4×4A regular interval timer counts down four minutes the moment you press start — whether your heart rate is at 60% or 90%. Two minutes of ramp-up means two minutes of “interval” that never reached VO₂max. Sessions stop being comparable, and progress stops being trackable.
The timer only counts when your HR is above 85% of max. Ramp up at your own pace; drop below the threshold mid-interval and the clock pauses until you climb back. Every session delivers exactly 4 × 4 minutes of true VO₂max work.
VO2max is the
strongest predictor
of how long you live.
Higher than smoking status, higher than blood pressure, higher than diabetes. The Norwegian 4×4 is the most efficient way to move it — and because Stellar keeps every interval identical, the gains show up in a recovery number you can actually track.
Bring your
own gear.
Three sources, one protocol. Pair a Polar strap, a Garmin watch, or AirPods Pro 3 — Stellar Intervals reads your heart rate live and runs the threshold logic regardless of where the beats come from.
Train at
VO₂max.
Pair a Polar strap, a Garmin watch, or AirPods Pro 3 and start your first 4×4 in under a minute.
