# VO2 Flow: Norwegian 4x4 Timer — Norwegian 4x4 Interval Trainer

> Norwegian 4x4 Interval Trainer (iPhone/iPad app by Discotto Labs L.L.C..)

- Source: https://appshunter.io/ios/app/vo2-flow-norwegian-4x4-timer/id6757104585 (this page in markdown: same URL + `.md`)
- Developer: [Discotto Labs L.L.C.](https://appshunter.io/developer/1864553330)
- Category: Health & Fitness, Sports
- Price: Free with in-app purchases
- Age rating: 4+
- Requires: iOS 13.0 · 25 MB
- Languages: English
- Released: 2026-02-13
- Data updated: 2026-07-26
- User reviews in markdown: https://appshunter.io/ios/app/vo2-flow-norwegian-4x4-timer/id6757104585/reviews.md

## What is VO2 Flow?

VO2 Flow is built for the Norwegian 4x4 protocol, the research-backed interval method athletes use to raise VO2max. Four 4-minute intervals at 90 to 95% max heart rate, with 3-minute recoveries. Studies show a 10% VO2max increase in 8 weeks.

Run Norwegian 4x4 or build your own protocol. Tabata. 10x1. 8x2. Any work and rest combination, any number of rounds.

Free in the app:
- Norwegian 4x4 protocol built-in and ready to start
- Workout history, every completed session logged and grouped by month
- One custom interval profile
- Apple Music integration, album art and controls during your session
- Audio cues and haptic feedback on every phase transition
- Keep screen awake during workouts
- Landscape and portrait support

Pro upgrade, $4.99 one-time:
- Remove all ads forever
- Unlimited custom interval profiles
- Achievement badges, 7 milestones you can share
- Every future Pro feature, no subscription

This is a timer, not a fitness platform. No social feed. No subscription. No complexity. Launch, pick a profile, start.

## Pricing and in-app purchases

Base price: Free.

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| Pro Upgrade | $4.99 | one-time |



## Version history (last 4 releases)

### 2.6.1 — 2026-06-14

Your full workout history is now available to everyone, free. Plus minor stability improvements.

### 2.2 — 2026-04-12

Small Bug Fix

### 2.0 — 2026-03-19

v2.0 is a major update

New in this version:

- Workout history - every session logged, grouped by month
- Achievement badges - 7 milestones, shareable to social
- Unlimited custom profiles - build any work/rest/interval combination
- Apple Music integration - artwork and controls during your session
- Haptic voice and sound feedback - Know when the stages change, even without looking at your phone. 

Pro upgrade: $6.99 one-time. No subscription.

### 1.0 — 2026-02-13

No release notes.

## Related topics

[4x4 hiit](https://appshunter.io/ios/topics/4x4-hiit)

---

*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-07-26.*