Norwegian 4x4 Heart Rate
VO2max interval timer with HR
Only for iPhone
Free · Designed for iPhone. Not verified for macOS.
iPhone
Norwegian 4×4 is the Helgerud VO2max interval protocol, built for athletes who want to push their aerobic ceiling.
Connect any Bluetooth heart-rate monitor — Whoop broadcast, Polar H10, Wahoo TICKR, Garmin HRM, or any device exposing the standard heart-rate service — and the app guides you through a 5 min warm-up, 4 × (4 min hard / 3 min easy), and 5 min cool-down.
A live heart-rate gauge shows when you're in the target zone (85–95% HRmax during work intervals, 60–70% during rest). The app speaks "Speed up" or "Slow down" until you hit the zone. Audio cues mark each phase transition; a 9-second countdown gives you time to start working out.
All data stays on your phone. No accounts, no analytics, no servers.
Ratings & Reviews
Added Live Activities on lock screen
The developer, Abe Stanway, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Abe Stanway
- Size
- 906.2 KB
- Category
- Health & Fitness
- Compatibility
Requires iOS 17.0 or later.
- iPhone
Requires iOS 17.0 or later. - Mac
Requires macOS 14.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
- English
- Age Rating
9+
- 9+
- Contains
Health or Wellness Topics
- Copyright
- © Abraham Stanway, 2026