Viking 4x4 is a fully guided Norwegian 4x4 interval timer for iPhone: 4 minutes hard, 3 minutes easy, four rounds, with a voice in your ear for every phase. Your first full session is free — and unlike a plain timer, it shows live heart rate, per-interval reports, and recovery trends, so you know the protocol is working.
Norwegian 4x4 timer
A 4x4 timer that knows whether you were in the zone.
4 hard · 3 easy · repeat 4 times · ~45 minutes
Timers are easy. Most 4x4 apps stop there.
Any countdown app can beep every four minutes. The Norwegian 4x4 protocol only works if those four minutes actually happen at 85–95% of your max heart rate — and the proof it's working shows up in your 60-second heart rate recovery, not on a stopwatch. Viking 4x4 gives you the timer and the measurement: voice-guided phases, live Apple Watch heart rate over color-coded zones, minute alerts and a 20-second finish cue, and a SKÅL report after every session.
Comparing options? Here's our honest breakdown of the best Norwegian 4x4 apps — including the free timers we think are solid.
Norwegian 4x4 timer questions
Is Viking 4x4 a Norwegian 4x4 timer?
Yes. Viking 4x4 runs the full protocol as a guided timer — 10-minute warm-up, four 4-minute work intervals with 3-minute recoveries between them, 10-minute cooldown — with voice cues for every phase. Your first full session is free, and it works with or without an Apple Watch.
What should a 4x4 interval timer include?
At minimum: the studied structure (4 min at 85-95% of max heart rate, 3 min easy between intervals), adjustable phases, and alerts you can follow without looking at a screen. Ideally it also shows whether you actually hit the target zone — which requires live heart rate, not just a countdown.
Why isn't a plain timer enough for the Norwegian 4x4?
The protocol's entire point is time at 85-95% of max heart rate. A stopwatch can't tell you whether you were in the zone or how your heart is adapting. Live heart rate, per-interval reports, and recovery trends turn the same 45 minutes into measurable progress.
How long is a Norwegian 4x4 timer session?
About 45 minutes: a 10-minute warm-up, four 4-minute work intervals separated by three 3-minute recoveries, and a 10-minute cooldown. Only 16 of those minutes are hard.
SKÅL!
The timer is free. The proof is the point.
Download on theApp StoreFree download · First 4x4 free
Your first 4x4 is free · iPhone · Apple Watch companion