Changelog

What's new

Every release, with the date it shipped and what actually changed. Nothing on this page is a plan — anything still in review says so.

1.2 In review Submitted September 2026

A way to try the whole idea in twelve minutes, and a long list of things the watch was doing wrong.

New
  • A free short session. One interval, about twelve minutes, warm-up and cool-down included. It is the real thing, once instead of four times — long enough to feel what a 4×4 interval is and to get your first heart rate recovery number. No subscription, no heart rate hardware needed.
  • The upgrade screen waits. It no longer appears until you have finished a session. There is nothing worth selling before you have seen what the app does.
  • The Health permission screen says what Apple's does not: Apple's sheet opens with every switch turned off, and tapping Allow without turning them on grants nothing. If access is off, the main screen says so and links to Settings.
Apple Watch
  • The short session now runs correctly when you start it from your phone. It used to fall back to the full forty minutes.
  • Your phone and your watch now show the same number of intervals.
  • Battery. The watch no longer keeps a workout session or its timers running after a workout ends, and no longer re-queues finished workouts every time you switch apps on your phone.
  • If your phone stops responding mid-session, the watch tells you and gives you a way out instead of freezing.
Fixed
  • Done on the summary screen sometimes needed several taps.
  • The monthly average no longer counts sessions where heart rate was never measured — one session by feel used to drag it down by a third.
  • An exported PDF no longer prints a large 0% for a session that had no heart rate data.
1.1 Live 31 August 2026

The release that stopped requiring AirPods. Before this, no heart rate sensor meant no workout at all.

New
  • Your Apple Watch runs the whole session. Heart rate from your wrist, phases, haptics and the summary. Leave the phone at home. Start from either device and the other one follows along, and says which is which.
  • AirPods fall back to the watch. Take them out mid-workout and your watch takes over as the sensor without stopping the session.
  • Train by feel. With no sensor at all, the full 4×4 protocol runs on the clock and tells you how hard each phase should feel.
  • An eight-week program. 24 sessions, three a week — the dose the research actually used. Miss a day and nothing breaks; the schedule shifts.
  • Heart rate recovery. How fast your pulse falls in the first minute after an interval. It improves in two to three weeks, long before VO₂ Max moves.
  • Recovery Trend — your recovery week over week. Pro.
  • Live Activity on the lock screen: phase and time left without unlocking.
Fixed
  • The workout screen could get stuck when the watch went out of range.
  • Clearer subscription terms before you buy.
1.0.1 Live 25 August 2026

Housekeeping. Nothing you could see, which turned out to be the problem worth fixing next.

  • Correct version reporting and first-launch handling.
  • Groundwork for measuring where people actually get stuck — the work that produced everything in 1.1 and 1.2.
1.0 Live March 2026

First release.

  • The Norwegian 4×4 protocol: ten minutes warm-up, four intervals of four minutes, three minutes of recovery between them, five minutes cool-down.
  • Live heart rate from AirPods Pro 3 and Powerbeats Pro 2, with zones computed from your own resting heart rate and age.
  • Session history and per-interval zone accuracy.

NTRVL is worked on almost every day. Most of that work never becomes a line on this page — it is testing, and finding that something quietly lies to you, and fixing it. When it does become a line, it is because it shipped.