---
title: "N4x4 - Reviews, Revenue and Downloads in United States | Apple App Store"
description: "The best Norwegian 4x4 App on the App Store. Train the Norwegian 4x4 without watching the clock or guessing your effort.  N4x4 reads your live heart rate — from Apple Watch, AirPods Pro 3, Garmin, WHO"
---

# N4x4 — United States
> Gold Standard for VO2 Max

![N4x4 App Icon](https://is1-ssl.mzstatic.com/image/thumb/Purple211/v4/a9/38/b7/a938b725-5218-275d-b260-1401cafd3a77/AppIcon-0-0-1x_U007ephone-0-1-P3-85-220.png/434x0w.png)

**Developer:** [Jan van Rensburg](https://apptail.io/developer/jan-van-rensburg-LuNf)
**Category:** Health Fitness
**Rating:** 4.4/5 (15 ratings)
**Price:** Free
**Bundle ID:** Jan-van-Rensburg.N4x4
**Store:** Apple App Store
**Country:** United States
**Version:** 5.7 (released 2026-09-30)
**Original Release:** 2024-09-16
**Languages:** English

**App Store Link:** [Download on Apple App Store](https://apps.apple.com/us/app/app/id6686407796)
**AppTail Page:** [https://apptail.io/app/n4x4-Iitt/united-states](https://apptail.io/app/n4x4-Iitt/united-states)

## N4x4 Description
The best Norwegian 4x4 App on the App Store. Train the Norwegian 4x4 without watching the clock or guessing your effort.

N4x4 reads your live heart rate — from Apple Watch, AirPods Pro 3, Garmin,
WHOOP, Polar, or any Bluetooth monitor — and turns it into clear push, hold,
and ease-off cues through every interval. When you finish, you see exactly how
long you held the target zone, and how today compared with last time.

Four 4-minute efforts, three easy recoveries. 33 minutes, warm-up and cooldown
included. It trains VO2 max, the fitness marker most closely tied to how well
you age, and it's one of the most studied ways to raise it. If you're going to
invest time in your health, this is a strong place to start.

HIT THE RIGHT ZONE
• Target zones calculated from your own max heart rate
• The number turns orange when you're below the zone and red when you're
  above, on both iPhone and Apple Watch
• Spoken and haptic nudges when you drift out and stay out
• A haptic countdown into every interval change: two taps, then the buzz

USE THE SENSOR YOU ALREADY OWN
• Apple Watch: install N4x4 on your wrist and heart rate streams automatically
• AirPods Pro 3: the earbuds you're already wearing double as your heart rate
  monitor (iPhone on iOS 26)
• Garmin (Broadcast Heart Rate), WHOOP (HR Broadcast), Polar, Wahoo, COROS,
  Powerbeats Pro 2, and any standard Bluetooth chest strap or armband
• Wearing more than one? You choose which source wins
• A built-in guide with exact, per-model setup steps

EASY TO KEEP THE HABIT
• Voice coaching through every interval, with the phone locked and your music
  ducked
• Night-before, morning-of, and comeback reminders — each on its own switch
• Weekly streaks, and a Live Activity on the Lock Screen and Dynamic Island

FINISH WITH PROOF
• Every interval charted against its target zone
• Time in zone, time to zone, and a note per interval for your settings
• Last session laid over today's, so progress is easy to see
• Your usual workout — Cycle, Run, Kettlebells, and more — pre-selected when
  you save

SEE THE PAYOFF
• Your VO2 max trend from Apple Health
• Training calendar, milestones, and full session history

Works on the treadmill, rower, bike, stair climber, with kettlebells, or on
the open road — any cardio that gets your heart into the zone.

No account. No subscription. No ads. Your data stays on your device and in
Apple Health.

Start with one hard session a week. Add a second when you're ready.

## N4x4 Screenshots
- [Screenshot 1](https://is1-ssl.mzstatic.com/image/thumb/PurpleSource221/v4/67/5f/51/675f5109-af77-b0f1-6427-5b1fd37b7cef/04-history.png/1284x2778.png)
- [Screenshot 2](https://is1-ssl.mzstatic.com/image/thumb/PurpleSource221/v4/11/58/fe/1158fe6c-62f1-77b9-00fc-e719b3b1a0c2/02-zones.png/1284x2778.png)
- [Screenshot 3](https://is1-ssl.mzstatic.com/image/thumb/PurpleSource221/v4/0a/9e/77/0a9e77b0-b6ea-a084-39ee-7b8a4c8d40c3/05-summary.png/1284x2778.png)
- [Screenshot 4](https://is1-ssl.mzstatic.com/image/thumb/PurpleSource211/v4/0b/12/c1/0b12c174-eb75-0f4b-d2da-4075db4eaeb8/06-heart-rate.png/1284x2778.png)
- [Screenshot 5](https://is1-ssl.mzstatic.com/image/thumb/PurpleSource211/v4/d8/2c/4f/d82c4f9e-6388-5871-fd34-26a20c57e22c/03-watch.png/1284x2778.png)
- [Screenshot 6](https://is1-ssl.mzstatic.com/image/thumb/PurpleSource221/v4/54/0b/ad/540badb3-02e8-d959-4fa8-6843371d11b0/01-home.png/1284x2778.png)

## N4x4 Rating Breakdown in United States
- 5 stars: 11 (73%)
- 4 stars: 0 (0%)
- 3 stars: 3 (20%)
- 2 stars: 1 (7%)
- 1 stars: 0 (0%)

## N4x4 Reviews in United States

### ***** "Great App"
Very nice app that is easy to use with ability to adjust elements of the training protocol to fit the need/capacity of people at different levels. 
It would be good to be able to see my target HR range easier. Love the color coding, just need the numbers bigger when on my phone.
Love it! Exceptionally useful.
-- RWaltonMouw, 2026-09-11

### ***-- "VO2 max history chart missing"
App works well for HIIT on my elliptical using a Garmin HRM chest strap, but the VO2 max history chart does not appear anywhere. Sharing with Apple Health is turned on, so I don’t know what the problem is.
-- ChuckDaniel1, 2026-08-05

### ***** "Great and Free"
Exactly what I was looking for. Great UI, simple and focused on running for better health and better VO2max. 
Suggestions:
1. Please add a feedback option in the app as a way to send feedback or bugs.
2. Would be highly appreciated if you could add support for health wearables that broadcast their HR (Like Whoop).
Thank you
-- seali33, 2026-07-14

### ***** "Excellent update"
I have been using this app for 6 weeks. The original version was basic and effective. For a free app, I couldn’t be happier. The update adds everything I was missing and compensating for by running multiple apps at the same time during the workout. Thank you!
-- Skootchover, 2026-07-13

### **--- "No live Heart Rate"
Disappointing. Screen should show live heart rate or at least zone during the exercise.
-- bgumbko, 2026-05-27

### ***-- "Needs HR in display"
All it shows is time and target heart rate in the interval.  Takes up whole screen as it should…but didn’t find a way to display my live heart rate.  So it’s just a timer if you ask me.
-- Gr280, 2026-05-21

### ***** "10/10"
The app does exactly what it should and it does so with style.
-- FonzyBekker, 2024-10-11

[View all N4x4 reviews and detailed analytics on AppTail](https://app.apptail.io/signup?utm_campaign=ai-crawl&utm_content=reviews)





## N4x4 Available In
- [United States](https://apptail.io/app/n4x4-Iitt/united-states)
- [Canada](https://apptail.io/app/n4x4-Iitt/canada)
- [United Kingdom](https://apptail.io/app/n4x4-Iitt/united-kingdom)
- [Australia](https://apptail.io/app/n4x4-Iitt/australia)
- [Brazil](https://apptail.io/app/n4x4-Iitt/brazil)
- [Spain](https://apptail.io/app/n4x4-Iitt/spain)
- [Ukraine](https://apptail.io/app/n4x4-Iitt/ukraine)
- [Israel](https://apptail.io/app/n4x4-Iitt/israel)
- [Germany](https://apptail.io/app/n4x4-Iitt/germany)
- [Sweden](https://apptail.io/app/n4x4-Iitt/sweden)
- [Belgium](https://apptail.io/app/n4x4-Iitt/belgium)
- [Netherlands](https://apptail.io/app/n4x4-Iitt/netherlands)
- [Ecuador](https://apptail.io/app/n4x4-Iitt/ecuador)
- [Egypt](https://apptail.io/app/n4x4-Iitt/egypt)
- [Finland](https://apptail.io/app/n4x4-Iitt/finland)
- [France](https://apptail.io/app/n4x4-Iitt/france)
- [Greece](https://apptail.io/app/n4x4-Iitt/greece)
- [Croatia](https://apptail.io/app/n4x4-Iitt/croatia)
- [Hungary](https://apptail.io/app/n4x4-Iitt/hungary)
- [Indonesia](https://apptail.io/app/n4x4-Iitt/indonesia)
- [Ireland](https://apptail.io/app/n4x4-Iitt/ireland)
- [India](https://apptail.io/app/n4x4-Iitt/india)
- [Iceland](https://apptail.io/app/n4x4-Iitt/iceland)
- [Italy](https://apptail.io/app/n4x4-Iitt/italy)
- [Japan](https://apptail.io/app/n4x4-Iitt/japan)
- [South Korea](https://apptail.io/app/n4x4-Iitt/south-korea)
- [Kuwait](https://apptail.io/app/n4x4-Iitt/kuwait)
- [Lebanon](https://apptail.io/app/n4x4-Iitt/lebanon)
- [Sri Lanka](https://apptail.io/app/n4x4-Iitt/sri-lanka)
- [Malta](https://apptail.io/app/n4x4-Iitt/malta)
- [Mexico](https://apptail.io/app/n4x4-Iitt/mexico)
- [Nigeria](https://apptail.io/app/n4x4-Iitt/nigeria)
- [Peru](https://apptail.io/app/n4x4-Iitt/peru)
- [Philippines](https://apptail.io/app/n4x4-Iitt/philippines)
- [Pakistan](https://apptail.io/app/n4x4-Iitt/pakistan)
- [Poland](https://apptail.io/app/n4x4-Iitt/poland)
- [Portugal](https://apptail.io/app/n4x4-Iitt/portugal)
- [Romania](https://apptail.io/app/n4x4-Iitt/romania)
- [Russia](https://apptail.io/app/n4x4-Iitt/russia)
- [Slovenia](https://apptail.io/app/n4x4-Iitt/slovenia)
- [Thailand](https://apptail.io/app/n4x4-Iitt/thailand)
- [Tunisia](https://apptail.io/app/n4x4-Iitt/tunisia)
- [Türkiye](https://apptail.io/app/n4x4-Iitt/turkey)
- [Taiwan](https://apptail.io/app/n4x4-Iitt/taiwan)
- [United Arab Emirates](https://apptail.io/app/n4x4-Iitt/united-arab-emirates)
- [South Africa](https://apptail.io/app/n4x4-Iitt/south-africa)
- [Armenia](https://apptail.io/app/n4x4-Iitt/armenia)
- [Argentina](https://apptail.io/app/n4x4-Iitt/argentina)
- [Azerbaijan](https://apptail.io/app/n4x4-Iitt/azerbaijan)
- [Bulgaria](https://apptail.io/app/n4x4-Iitt/bulgaria)
- [Bahrain](https://apptail.io/app/n4x4-Iitt/bahrain)
- [Belarus](https://apptail.io/app/n4x4-Iitt/belarus)
- [Chile](https://apptail.io/app/n4x4-Iitt/chile)
- [Colombia](https://apptail.io/app/n4x4-Iitt/colombia)
- [Czechia](https://apptail.io/app/n4x4-Iitt/czechia)
- [Dominican Republic](https://apptail.io/app/n4x4-Iitt/dominican-republic)
- [Algeria](https://apptail.io/app/n4x4-Iitt/algeria)

---

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