10/10
The app does exactly what it should and it does so with style.
Free
About
This app guides you through the scientifically-backed Norwegian 4x4 HIIT protocol to efficiently boost your VO2 Max and cardiovascular health. It offers set-and-forget workouts with visual and audio cues, suitable for all fitness levels.
✓Norwegian 4x4 HIIT protocol
✓Set-and-forget workout structure
✓Visual and audio interval cues
✓Real-time heart rate zone display
✓5-minute warm-up
✓4 rounds of 4-minute intervals
✓3-minute recovery periods
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What's New in N4x4
3.44
April 3, 2026
Added advanced tips.
User reviews
Developer apps
FAQ
What is the Norwegian 4x4 HIIT protocol used in N4x4?
The Norwegian 4x4 HIIT protocol involves 4 rounds of 4-minute high-intensity intervals, with 3-minute recovery periods between each round. This structured approach is scientifically proven to be highly effective for boosting VO2 Max.
How does N4x4 help with VO2 Max?
N4x4 focuses on the Norwegian 4x4 HIIT protocol, which is recognized as one of the most efficient methods for improving VO2 Max. A higher VO2 Max is a key indicator of cardiovascular health and longevity.
Is N4x4 suitable for beginners?
Yes, N4x4 is designed for both beginners and advanced athletes. The app provides clear visual and audio cues to guide users through each interval, making it accessible regardless of fitness level.
Does N4x4 require a subscription?
No, N4x4 is completely free to use. The app states it has no strings attached, meaning there are no sign-ups, ads, or in-app purchases required to access its full functionality.
Does N4x4 have ads?
No, N4x4 is ad-free. The app explicitly states that it contains no advertisements, ensuring an uninterrupted workout experience for users.
What devices does N4x4 support?
Based on the provided data, N4x4 currently supports iPhones. Information on Android compatibility is not specified in the current data.
How often is N4x4 updated?
The latest version of N4x4 is 3.44, which was last updated on April 3, 2026. This indicates a recent update, suggesting ongoing development and support for the application.
What is the age rating for N4x4?
N4x4 has an age rating of 4+. This means it is considered suitable for users of all ages, with no specific content restrictions.
