# HIIT 4x4 Lite — Interval Training Meter

> Apple Watch HIIT interval training meter based on Maximum Heart Rate. (iPhone/iPad app by Eastridge Technology.)

- Source: https://appshunter.io/ios/app/hiit-4x4-lite/id1558498996 (this page in markdown: same URL + `.md`)
- Developer: [Eastridge Technology](https://appshunter.io/developer/392920417)
- Category: Health & Fitness, Sports
- Price: Free
- Rating: 5.00/5 from 2 App Store ratings · 3 written reviews indexed
- Age rating: 4+
- Requires: iOS 12.0 · 18 MB
- Languages: English
- Released: 2022-09-13
- Data updated: 2026-06-10
- Monetization: free
- User reviews in markdown: https://appshunter.io/ios/app/hiit-4x4-lite/id1558498996/reviews.md

## What is HIIT 4x4 Lite?

HIIT 4x4 Lite is an Apple Watch exercise monitoring app for High Intensity Interval Training (HIIT). The app sequences exercise between high and low intensity intervals. The intensity of the exercise is measured as a percentage of your Maximum Heart Rate (MHR). 

The HIIT 4x4 intervals are as follows:

- 10 minutes warmup at 60% MHR
- 4 minutes high intensity at 90% MHR
- 3 minutes low intensity at 70% MHR
- repeat high-low intervals 4 times (4 high intensity intervals of 4 minutes each = 4x4).

HIIT 4x4 Lite uses a speedometer type dial to display heart rate. When the arrow is in the green zone then your heart rate is within the interval target.  If the heart rate later  falls out of the target range, warning chimes are issued until back in range.

Each person's MHR is different, and changes with age. A commonly used formula for MHR is 220 - age in years. A more accurate number can be discovered by using a heart monitor during all out exercise and observing the highest heart rate achieved.

HIIT 4x4 Lite does NOT store your workout history using Apple Health. Please use the full version HIIT 4x4 (not Lite) to store workout history.

HIIT 4x4 Lite is based on the High Intensity Interval Training 4x4 program developed by the Norwegian University of Science and Technology's Cardiac Exercise Group.

## Key features

- High Intensity Interval Training (HIIT) guidance
- Heart rate monitoring based on MHR percentage
- Speedometer-style heart rate dial
- Warning chimes for out-of-range heart rate
- Based on NTNU's 4x4 HIIT program

## Recent user reviews (3 of 3)

All indexed reviews: https://appshunter.io/ios/app/hiit-4x4-lite/id1558498996/reviews.md

### 1/5 — Lite version is poison

*2025-01-31*

The description of the light version said that I’m like pro it can’t record workouts. This was fine and I started a workout using my watches usual mechanism then switched to the HIIT app. What I learned afterwards is that it had stopped the original workout. Furthermore, it prevented my watch. From recording the workout at all. Spent an hour manually correcting data in the Health app, but even then wasn’t completely successful. For somebody who’s engaged in an actual training regimen, who is careful about logging activity and tracking their training load. Just trying this app out turns out to be very destructive zero out of 10 will not try again.

### 5/5 — What does the paid version do?

*2024-05-08*

What are the limitations to the Lite version that the paid version can do? For me this version does not stop after 4 intervals.

### 5/5 — Simple, works great, finally a Norwegian 4 app!

*2024-02-01*

This app is great. It is easy to use , the explanations are very detailed, it works flawlessly. Turn it on and it will give you your max heart rate. It has a timer for when you 4 minutes are done and the beeps plus dial on colors really help a lot when you are exercising hard and you can’t fumble with your watch. If you’re into HIIT, this is the one for you. I’ve been doing HIIT for years and I finally found an app. that’s easy and efficient. Even took the time to review it and I rarely review apps, shows you how much I like it.

## Frequently asked questions about HIIT 4x4 Lite

### What is the HIIT 4x4 Lite workout structure?

HIIT 4x4 Lite follows a structure of 10 minutes warmup at 60% MHR, followed by 4 minutes high intensity at 90% MHR, then 3 minutes low intensity at 70% MHR. This high-low interval sequence is repeated 4 times.

### How does HIIT 4x4 Lite measure exercise intensity?

Intensity is measured as a percentage of your Maximum Heart Rate (MHR). The app uses a speedometer dial to show if your heart rate is within the target zone for each interval.

### Does HIIT 4x4 Lite store workout history?

No, HIIT 4x4 Lite does not store your workout history using Apple Health. For workout history storage, you would need to use the full version of the app, HIIT 4x4.

### How is MHR calculated in HIIT 4x4 Lite?

The app uses a commonly used formula of 220 - age in years to estimate MHR. For a more accurate number, it's recommended to use a heart monitor during intense exercise to find your highest achieved heart rate.

### Does HIIT 4x4 Lite have ads?

No, HIIT 4x4 Lite is ad-free, providing an uninterrupted workout experience.

### What devices is HIIT 4x4 Lite compatible with?

HIIT 4x4 Lite is compatible with Apple Watch, iPhone, and iPod devices.

### How often is HIIT 4x4 Lite updated?

The latest version, 1.08, was released on September 22, 2024. The app is actively maintained by Eastridge Technology.

### What is the age rating for HIIT 4x4 Lite?

HIIT 4x4 Lite has an age rating of 4+, making it suitable for a wide range of users.

## Version history (last 2 releases)

### 1.08 — 2024-09-22

The Start button was moved to the Settings screen to streamline operation.

### 1.06 — 2022-09-13

No release notes.

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## More apps by Eastridge Technology

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- [Hearts: Shoot the Moon](https://appshunter.io/ios/app/hearts-shoot-the-moon/id1547434423)

All apps by Eastridge Technology: https://appshunter.io/developer/392920417

## Related topics

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

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*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 2026-06-10.*