Visual improvement and fixes based on feedback from users. Same amazing simplicity and focus on your Norwegian 4x4 HIIT workout.

Visual improvement and fixes based on feedback from users. Some amazing simplicity and focus on your HIIT workout.

Improvements of the background locked-screen mode (thanks, Chris, for the feedback). Same simplicity.

Improvements of the background mode (thanks Chris for a feedback). Same simplicity.

Improved background timer. Same simplicity and classical Norwegian 4x4 Protocol spot-agistic timers. Apply for running, HIIT, rowing, jumping, or any other sport of your choice and follow visual and audio cues.

Improved Warm-up screen with customizable timers in Settings, improved HR readings from Apple Health. Added countdown for exercise start, haptic feedback/vibrations and a dynamic/app widget for a lock screen.

Same simplicity and classical Norwegian 4x4 Protocol spot-agistic timers. Apply for running, HIIT, rowing, jumping, or any other sport of your choice and follow visual and audio cues.

Thanks to C.A., Maria, Alvaro, March and Matt for the feedback and waiting!

- Improved HR readings from Apple Health
- Fixed audio cues when in background mode, as well as different horn sounds to differentiate the type of workout (intensive vs. cooldown)
- Now our app supports a background timer mode: switch to the Spotify or Garmin app, or just lock your phone and only follow audio cues if you prefer - the time is ticking
- Thanks for being with us all this time! The Norwegian 4x4 app has experienced significant growth over the last few weeks and has been featured on Tim Ferriss' Blog

Same simplicity and classical Norwegian 4x4 Protocol spot-agistic timers. Apply for running, HIIT, rowing, jumping, or any other sport of your choice and follow visual and audio cues.

Thanks to Maria, Alvaro, March and Matt for the feedback and waiting!

- Fixed audio cues when in background mode, as well as different horn sounds to differentiate the type of workout (intensive vs. cooldown)
- Improved HR readings from Apple Watch (active workout)
- Now our app supports a background timer mode: switch to the Spotify or Garmin app, or just lock your phone and only follow audio cues if you prefer - the time is ticking
- Thanks for being with us all this time! The Norwegian 4x4 app has experienced significant growth over the last few weeks and has been featured on Tim Ferriss' Blog

Same simplicity and classical Norwegian 4x4 Protocol spot-agistic timers. Apply for running, HIIT, rowing, jumping, or any other sport of your choice and follow visual and audio cues.

Thanks to Alvaro, March, Maria and Matt for the feedback and waiting!

- Improved HR readings from Apple Watch (active workout)
- Now our app supports a background timer mode: switch to the Spotify or Garmin app, or just lock your phone and only follow audio cues if you prefer - the time is ticking
- Thanks for being with us all this time! The Norwegian 4x4 app has experienced significant growth over the last few weeks and has been featured on Tim Ferriss' Blog
- Also we did some little polishes and interface improvements.

Same simplicity and classical Norwegian 4x4 Protocol spot-agistic timers. Apply for running, HIIT, rowing, jumping, or any other sport of your choice and follow visual and audio cues.

Thanks to March, Maria and Matt for the feedback and waiting!

- Now our app supports a background timer mode: switch to the Spotify or Garmin app, or just lock your phone and only follow audio cues if you prefer - the time is ticking.
- Thanks for being with us all this time! The Norwegian 4x4 app has experienced significant growth over the last few weeks and has been featured on Tim Ferriss' Blog.
- Also we did some little polishes and interface improvements.

Same simplicity and classical Norwegian 4x4 Protocol spot-agistic timers. Apply for running, HIIT, rowing, jumping, or any other sport of your choice and follow visual and audio cues.

Thanks to Maria and Matt for the feedback and waiting!

- Now our app supports a background timer mode: switch to Spotify or Garmin app or just lock your phone and only follow audio cues if you prefer - the time is ticking.
- Thanks for being with us all this time! The Norwegian 4x4 app has grown dramatically over the last few weeks and has been mentioned in Tim Ferriss Blog.
- Also we did some little polishes and interface improvements. 

Same simplicity and classical Norwegian 4x4 Protocol spot-agistic timers. Apply for running, HIIT, rowing, jumping, or any other sport of your choice and follow visual and audio cues.

Thanks for being with us all this time! The Norwegian 4x4 app has grown dramatically over the last few weeks!

Little polishes and interface improvements. Same simplicity and classical Norwegian 4x4 Protocol spot-agistic timers. Apply for running, HIIT, rowing, jumping, or any other sport of your choice and follow visual and audio cues.

Little fixes and improvements. Same amazing simplicity.

Little technical improvements and polishing. Same amazing simplicity.

Improve calorie calculation accuracy and a little hint "Swift Left for Settings". Same simplicity. Keep rocking!

Long awaited by our loyal users: Heart Rate monitoring/displaying on a main screen (subject of your sensors or watch compatibility and if they send the data to Apple Health). The average value over the last two measurements fetches every 5 seconds will be displayed during the Norwegian 4x4 active interval of workout, cooldown or warm-up exercise. It heart rate won't update if your watch or sensor doesn't send HR data constantly to Apple Health.

Long awaited by our loyal users: Heart Rate monitoring/displaying on a main screen (subject of your sensors or watch compatibility and if they send the data to Apple Health). The average value over the last two measurements fetches every 5 seconds will be displayed during the Norwegian 4x4 active interval of workout, cooldown or warm-up exercise.

Improvements and fixes in accuracy of workouts calculation with and without custom timers, as well as pushing this data to Apple Health.

Improvements and fixes in accuracy of workouts calculation with and without custom timers, as well as pushing this data to Apple Health.

Improvements and fixes. Same amazing simplicity and dedication to keep your HR and VO₂ Max levels, making your heart younger.

Why is VO₂ Max Important?

VO₂ max, or maximal oxygen uptake, refers to the maximum amount of oxygen your body can utilize during intense exercise. It’s a critical measure of cardiovascular fitness and endurance, used to assess how well your body can use oxygen to generate energy.

VO₂ max is widely regarded as one of the best indicators of cardiovascular health. The higher your VO₂ max, the better your endurance and the more efficient your body is at using oxygen. It’s a key metric for athletes, and improving it offers numerous benefits:

- Enhanced performance in endurance sports.
- Better cardiovascular health and reduced risk of heart disease.
- Improved overall fitness, making daily activities easier.

Heart Rate Zones and Their Impact

Heart rate zones, typically expressed as percentages of your maximum heart rate (HRmax), are categorized as follows:

- Zone 1: Warm-up Zone (50-60% of HRmax) - This is a light-intensity zone used for warming up and cooling down. It’s great for recovery and increasing blood flow without putting too much strain on the heart.
- Zone 2: Fat Burning Zone (60-70% of HRmax) - Known as the “fat-burning zone,” this moderate-intensity range allows for sustained activity and has been found to improve endurance while using fat as the primary fuel source. It’s also optimal for improving cardiovascular health with lower impact on the joints.
- Zone 3: Aerobic Zone (70-80% of HRmax) - Working in this zone enhances your body’s aerobic capacity and strengthens the heart. Recent studies have highlighted that exercising in this range can improve VO₂ max, the body’s ability to use oxygen efficiently.
- Zone 4: Anaerobic Zone (80-90% of HRmax) - This high-intensity zone is associated with HIIT (high-intensity interval training). Pushing the body into this zone improves speed and power and stimulates the cardiovascular system to adapt. HIIT has been shown to be particularly effective for improving VO₂ max, which is closely tied to longevity.
- Zone 5: Red Line Zone (90-100% of HRmax) - This zone is where the body operates at maximum effort. While it’s not sustainable for long durations, pushing yourself into this range helps improve maximal performance and burns the most calories in the shortest time.

Check out our app and start training with Norwegian 4x4 Protocol to make your heart stronger, healthier and younger.

Improvements and fixes. Same amazing simplicity and dedication to keep your HR and VO₂ Max levels, making your heart younger.

Improvements and fixes. Same amazing simplicity of the app.

Tiny bits of polishing and improvements for larger screens like iPhone 16 Max and Max Pro. Same amazing simplicity of the app.

We love receiving your feedback and implementing new useful features! This week we've implemented:

1. An optional warm-up routine was added before the main workout (is off by default, but can be switched on in Settings - swipe right on the main screen).
2. The accuracy of calorie calculation is considered (considering warm-up or without).
3. Table with workout history (click on the upper-calorie counter on the main screen).

Special thanks to Louise, Chad and Marc for the contributions!

Please keep the feedback going! How else we can make it better for you?

Your feedback helps us improve the app!

This time we've improved the font scalability for large and small screens (think iPhone vs iPad or even macOS desktop, yes, it is also used by some of our clients in the gyms broadcasted to a group of people sweating their HIIT out the Norwegian style).

Coming up next: optional 10-minutes warm-up session before your hit that heat!

Thanks for being with us and helping us to make our app better every single time.