VO2 Flow: Norwegian 4x4 Timer
HIIT Intervals for VO2max
Free · In‑App Purchases · Designed for iPad. Not verified for macOS.
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.
Ratings & Reviews
Your full workout history is now available to everyone, free. Plus minor stability improvements.
The developer, CHRISTOPHER DISCOTTO, 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 Used to Track You
The following data may be used to track you across apps and websites owned by other companies:
- Identifiers
- Usage Data
Data Linked to You
The following data may be collected and linked to your identity:
- Usage Data
Data Not Linked to You
The following data may be collected but it is not linked to your identity:
- Purchases
- Identifiers
- Usage Data
- Diagnostics
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Discotto Labs L.L.C.
- Size
- 25.9 MB
- Category
- Health & Fitness
- Compatibility
Requires iOS 13.0 or later.
- iPhone
Requires iOS 13.0 or later. - iPad
Requires iPadOS 13.0 or later. - iPod touch
Requires iOS 13.0 or later. - Mac
Requires macOS 11.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
- English
- Age Rating
4+
- 4+
- Contains
Advertising
- In-App Purchases
Yes
- Pro Upgrade $4.99
- Copyright
- © Chris Discotto 2026 Discotto