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What’s New Version 3.44
Added advanced tips.
Description
N4x4 - Norwegian 4x4 HIIT Trainer
Ready to transform your fitness? N4x4 brings you the scientifically-backed Norwegian 4x4 HIIT protocol—the most efficient way to boost your VO2 Max and build a bulletproof cardiovascular system.
WHY N4x4?
• It's set and forget: Press start, then just train. No fiddling with timers.
• Visual and audio cues guide you through every interval
• Perfect for beginners and advanced athletes alike
WHAT YOU GET:
• 5-minute warm-up to prepare your body
• 4 rounds of 4-minute high-intensity intervals
• 3-minute recovery periods between rounds
• Real-time heart rate zone display based on your age
WHY VO2 MAX MATTERS:
Your VO2 Max is the single greatest predictor of lifespan. Studies confirm high-intensity interval training like Norwegian 4x4 is the most efficient way to improve it. Top longevity experts (like Dr. Peter Attia) swear by it.
NO STRINGS ATTACHED:
• 100% free
• No sign-ups
• No ads
• No in-app purchases
• Just you and your workout
Download N4x4 now and start building a stronger, healthier heart today. Your future self will thank you.
Accessibility
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Version history 11 versions
Build 884100736v3.442026-04-03 22:12:00
Added advanced tips.
Build 883033219v3.412026-03-05 01:30:17
Fixed LiveActivity bug, thanks to Bubbles.
Build 883055379v3.422026-03-05 21:20:44
Add the ability to manually adjust max heart rate and increased reliability of VO2 Max import from Apple Health.
Build 882884931v3.42026-03-03 15:21:42
VO2 Max Goals. Tips and Guidance.
Build 882819806v3.12026-02-28 01:10:44
Live activities, voice prompts and more!
Build 882718821v2.12026-02-26 00:20:03
Major Update: The Ultimate Norwegian 4x4 Experience
Streak Tracking
• Track your workout streaks with a beautiful visual calendar
• See your current streak and all-time best
• Tap any completed workout day to view details
Smarter Reminders
• Reminders now sent at 8pm the day BEFORE your scheduled workout
• Daily follow-up nudges until you log your workout
• Fun, encouraging Viking-themed messages to keep you motivated
Personalized Heart Rate Zones
• Enter your age during onboarding for accurate target heart rate zones
• See your target zones (85-95% for high intensity, 60-70% for recovery) displayed during each interval
• Train at the right intensity for maximum VO2 max improvement
Apple Health Integration
• Automatically save workouts to Apple Health
• Toggle on/off in Settings
• Track your VO2 max trends over time
UI Improvements
• Simplified post-workout flow
• Reorganized Settings for better usability
• Various bug fixes and performance improvements
Build 869353143v1.322024-09-28 22:35:58
New icon.
Build 869189621v1.312024-09-23 19:19:39
- Improved handling of background operation and notifications.
- Removed background audio capability
Build 869188719v1.22024-09-22 21:20:54
- The alarm at the end of the interval won't stop your music anymore. Sorry, that was annoying.
- Interval alarms will work even if your phone is set to silent.
Thanks to Leo for reporting these errors.
The website is also updated with more guidance on how to use the app effectively. See https://n4x4.app
Build 869050616v1.012024-09-18 10:01:45
Changed app store pictures.
Build 869025520v1.02024-09-16 23:47:11
No pricing data captured yet — comparisons appear once the app has paid storefronts or in-app purchases.
Availability 1 of 1 storefronts
| Region | Language | Price | Ratings | Avg | Version |
|---|---|---|---|---|---|
| US | en-US | Free | 6 | 4.2 | 3.44 |
Change log 15 changes · US
✎
releaseNotes updated
Added advanced tips.
✎
description updated
N4x4 - Norwegian 4x4 HIIT Trainer
Ready to transform your fitness? N4x4 brings you the scientifically-backed Norwegian 4x4 HIIT protocol—the most efficient way
✎
subtitle updated
Gold Standard for VO2 Max
✎
name updated
N4x4
◆
Version 3.44 released
Added advanced tips.
◆
Version 3.42 released
Add the ability to manually adjust max heart rate and increased reliability of VO2 Max import from Apple Health.
◆
Version 3.41 released
Fixed LiveActivity bug, thanks to Bubbles.
◆
Version 3.4 released
VO2 Max Goals. Tips and Guidance.
◆
Version 3.1 released
Live activities, voice prompts and more!
◆
Version 2.1 released
Major Update: The Ultimate Norwegian 4x4 Experience
Streak Tracking
• Track your workout streaks with a beautiful visual calendar
• See your current streak and all-time best
• Tap any completed workout day to view details
Smarter Reminde
◆
Version 1.32 released
New icon.
◆
Version 1.31 released
- Improved handling of background operation and notifications.
- Removed background audio capability
◆
Version 1.2 released
- The alarm at the end of the interval won't stop your music anymore. Sorry, that was annoying.
- Interval alarms will work even if your phone is set to silent.
Thanks to Leo for reporting these errors.
The website is also updated with
◆
Version 1.01 released
Changed app store pictures.
◆
Version 1.0 released