# Cardio Zones. — Heart rate based training

> Heart rate zone training app for Apple Watch and iPhone with advanced analytics. (iPhone/iPad app by Theo Scott.)

- Source: https://appshunter.io/ios/app/cardio-zones/id1103232564 (this page in markdown: same URL + `.md`)
- Developer: [Theo Scott](https://appshunter.io/developer/691156625)
- Category: Health & Fitness, Sports
- Price: $49.99
- Rating: 4.30/5 from 40 App Store ratings · 21 written reviews indexed
- Age rating: 12+
- Requires: iOS 15.6 · 28 MB
- Languages: American English, Afrikaans, Danish, Dutch, Finnish, French (France), German (Germany), Italian, Japanese, Korean and 4 more
- Released: 2016-09-17
- Data updated: 2026-06-28
- Monetization: paid
- User reviews in markdown: https://appshunter.io/ios/app/cardio-zones/id1103232564/reviews.md

## What is Cardio Zones.?

Take your Apple Watch (leave your iPhone at home), bluetooth headphones, go for a run, walk, cycle, spin (Schwinn bikes), gym, swim, row,  ....
- Use the voice assistant to regulate and keep your heart rate within target zones during workouts
- View cumulative graphs for time spent in heart rate zones for workouts, even for any workout recorded by other apps and stored in Apple Health
- Rate your fitness level, and recovery heart rate (Superior, Excellent, Good, Fair, Poor)
- Measure your Resting Heart Rate & VO2 Max, plus calculate your Max Heart Rate 
- Preloaded Heart rate training zones: Karvonen & Zoladz formulas, British Cycling Coaches, Joe Friel Running & Cycle and more.
- Create your bespoke heart rate zones.
- Find training zones for beginners, intermediates and professionals.
- Voice alarm warning guidance helping you stay in your training zones, with Bluetooth headphone support (listen to the funky comments on your progress during your workout)
- Real-time heart rate, statistical prediction and training zones are shown in a graph and text format.
- Location tracking of your routes with your heart rate data at each point on the map.
- Display heart rate data on maps and/or in a graph format.
- Export heart data to CSV on iCloud and use Excel and Numbers from your Mac or PC to analyse the raw data and build your own optimised training programme
- No login account is required, no external web accounts are needed, and you keep your data (strict privacy).
- No subscriptions are required, no extra payments, and full access immediately.
- Support portrait and landscape display modes.
- Support for Cycling Speed and Cadence Bluetooth service (Apple Watch only)

Your heart rate provides insight into how efficiently you’re training and gives you a way to quantify improvements. With zone training, you can yield different benefits and are appropriate at different times during a training plan, whether that is weight loss or improved cardiovascular performance. 

Zone training gives you focus. Measuring your heart rate and keeping within your zones can help you from overtraining. Overtraining can lead to exercise addiction which can lead to negative physiological and psychological effects, constant muscle soreness, elevated resting heart rate, burnout, reduced variability, elevated blood pressure, lack of appetite, and even becoming moody.

To get the best out of the app you need a heart rate sensor that conforms to the Bluetooth 4 Heart Rate Service (HRS) like the Polar H7 Smart, Wahoo TICKR, Bose Soudsport Pulse, etc.

You don’t have a heart sensor:
The following functions are available if you don’t have a bluetooth heart sensor or Apple Watch:
- Calculate your VO2 Max doing a 1½ mile run.
- Calculate your Maximum heart rate.
- Get optimal heart zones depending on your fitness goals (fat burn, cardio, et.c).
- References and reading material on how heart rate zones are used in fitness & sports sciences.

Data Privacy:
- Your data remain private in your iOS Device or iCloud Account. You are in control over who views or uses your data.
- This app works seamlessly with Apple Health
- You do not need any annoying login accounts.
- All data is stored on your iPhone/iPad/Apple Watch, and no data is on any external database on the internet or worldwide web.

Battery:
- Continued use of GPS running in the background can dramatically decrease battery life.
- Continued use of the Apple Watch heart rate sensor can dramatically decrease battery life.
- Viewing your heart rate in Graph mode will impact your battery life when the App is automatically (the icon with the wheel at the top) adjusting the XY-Axis. Tap on the wheel/settings icon at the top to switch to manual mode to conserve battery life and reduce the graphics power processing requirements.

Thank you for your time, and for support or new features request, send me an email from within the App: About | Contact or tweet @ZoneTrainingApp

## Key features

- Voice assistant for heart rate zone guidance
- Cumulative graphs of time in heart rate zones
- Fitness level and recovery heart rate rating
- Resting Heart Rate & VO2 Max measurement
- Preloaded and custom heart rate zones
- Location tracking of routes with heart rate data
- Export heart data to CSV for analysis

## Chart rankings

- #193 in Top Paid · Health & Fitness (US App Store)

## Recent user reviews (10 of 21)

All indexed reviews: https://appshunter.io/ios/app/cardio-zones/id1103232564/reviews.md

### 5/5 — Muito bom

*2025-09-24*

Aplicativo muito top!

**Developer response:** Obrigado pela sua avaliação.
Resolvi alguns erros recentemente em relação à conectividade com bluetooth. Se você ainda tiver problemas entre em contato comigo via twitter (https://twitter.com/ZoneTrainingApp/) ou envie-me um e-mail da seção de suporte no App

### 4/5 — Improvement as a whole exercise app

*2022-12-14*

This app is wonderful and accurate as it seems to refresh every second or two and dominating HR sensor signal so no unnecessary disturbance.

It will give 5 stars if they add a voice of encouragement through out the session that you choose… something like Nike Run Club would be ideal !  HR based or distance based!

**Developer response:** Thank you for the kind review.

The app will make remarks of encouragement when your calories hits 500 and 600.

I can understand why people like the trainer's remarks from the Nike app, that is because the Nike Run app is focused on getting you better at running.

The Cardio zones app was created so I can be focussed on staying in a specific zone, and measuring heart rate recovery but not specific for a particular sport like running, rowing, cycling, etc. 

Theo

### 2/5 — Won’t work if simultaneously using a fitness tracking app

*2022-02-24*

I was so excited when I found this app, since I use the Maffetone method and needed some thing to alert me when I was leaving my preferred cardio zone. However, I always use the map my fitness app on my Apple Watch to track all of my workouts. Unfortunately, CardioZones won’t work if I also use the MapMy Fitness app at the same time. This would’ve been perfect for me, if not for this issue! Dear developer, if at all possible please, please, please develop a solution so that other fitness tracking apps can be used simultaneously with CardioZones! 🙏🏻

**Developer response:** You can't run two workout session at the same time on watchOS. It is a restriction by Apple.

### 5/5 — Finally, a fully customizable HR app!

*2021-09-12*

Was thrilled to find this app!  My Rowing coach utilizes up to 11 separate zones which are individualized to each athlete and this app allows for that! Thank you for a great app and continued development.  The minutes per zone are valuable information though only found on the watch.  Also would be great to use with a Garmin as alternative to apple wAtch but that would just be a bonus!

**Developer response:** Thanks for the superstar review. My best feature of my own app is to do sprint runs/walks, I set up the zones so that when I walk my heart reduce reaching the lower zone bound, then telling me up to increase my pace, I run then, until my heart rate an upper limit, then telling me to slow down, so it goes on, up, down, up, down. Of course, takes to fine tune the zones, but it is easy, to tweak a zone, you just copy/paste the old one and then edit it.

### 3/5 — Font size for graphs on iPhone

*2021-02-21*

Nice app so far, but difficult for me to read the scale of the plots on the iPhone.  Is there a way of changing this within the app?  Thanks

**Developer response:** Hi

Sorry to hear that font size on there graph axes is a problem. You can view an increased font size (and the graph line plots) by zooming in on the graph by using the iOS Accessibility features:

iPhone Settings > Accessibility > Zoom > On

Theo

### 5/5 — Work Out apps

*2021-02-16*

I believe That your is the correct apps for my needs.  Spent a lot of money and time searching for the correct app. Had some problems connecting my polar sensor because I was using more the one sensor. 
I just want to thank you. 

Rudy

**Developer response:** Rudy,

Thank you for your kind review. I am glad you enjoy the app as much as I do. I initially developed the app for myself because there is nothing like it on the App Store and now others can also use it. 

Theo

### 5/5 — Perfect for my needs

*2020-11-22*

I have started Zone 2 training and needed an app that would give me voice prompts and allow me to set my own hr zone. With this app I can enter the zone I want to train in and it gives voice prompts when I am out of zone and back in zone. I can also get instant voice feedback of my stats with the motion of looking at my watch. I have tried several apps but none of them had the features I needed. I was hesitant to buy this app because of the price and my only regret is that I didn’t buy this one first. Also, the app developer is very responsive to questions. Can’t say enough about this app, I highly recommend.

### 5/5 — Galaxy Watch won’t connect

*2020-05-03*

I have an iPhone 8+ and a Samsung Galaxy Watch, which has bluetooth and connects nicely to my watch with a heart sensor. Cardio Zones cannot find my sensor on my watch. Why not? I’ve done everything logical to get it to find my watch but it won’t. Help please.

Thank you very much for your answer. I ordered an Apple Watch series 5 to use your app because I love what it can do for me at 65 in terms of heart health and my intense workouts with interval training using cardio zones.

**Developer response:** Your Samsung watch is proprietary to Samsung and does not conform to the Bluetooth 4 heart rate specification.  Examples of heart rate sensors that are complaint to this Bluetooth specification are Polar H7, Wahoo TICKR and others. 

The way the app works on Apple Watch is that it install a watchOS Cardio Zones app on an Apple Watch, which the user then use as shown in the screenshots on the App store. Your Samsung watch does not use the Apple watchOS operating system.

### 1/5 — Não conecta com gps do Apple Watch

*2020-04-16*

Muitas funcionalidades e importantes, porém peca no básico. As conexões tem q ser uma certeza. Se houverem passos a serem seguidos isso precisa estar claro nas explicações.

**Developer response:** Para que o GPS funcione corretamente, você precisa garantir que concedeu as permissões corretas no seu Apple Watch. Se você negou as permissões do aplicativo anteriormente, precisará alterá-lo das configurações do Apple Watch.

Às vezes, a reinicialização do Apple Watch resolve problemas.

Existem muitos exemplos e toturiais em https://twitter.com/ZoneTrainingApp

### 1/5 — Error writing workout results

*2020-03-08*

Even if give all access grants into the Health on Apple Watch, the error writing always happened.
And also, the app on the watch always ask for access into health.

Some tests on Calculator function are not working with Apple Watch....

**Developer response:** Hello thank your for your review.

If you contact me I can help you better with the error you getting. 

Permissions on the  Apple Watch Health is handled by watchOS and watchOS should store your chosen permissions. If it keeps asking you for permissions, then it is mostly likely that watchOS could not grant the permissions and that is  reason why the app could be not store your workout results in Apple Health. Contact me (via More > About > Support from the app ) to see how I can help, but you might want to contact Apple support to find out why Health permissions are not granted or stored.

## Frequently asked questions about Cardio Zones.

### What is the price of Cardio Zones?

Cardio Zones is a paid app priced at $49.99. There are no subscriptions or extra payments required for full access.

### What devices does Cardio Zones support?

Cardio Zones is supported on Apple Watch, iPhone, iPad, and iPod. It is designed to work with your Apple Watch, allowing you to leave your iPhone at home during workouts.

### How accurate is Cardio Zones?

The app relies on Bluetooth 4 Heart Rate Service compatible sensors for accurate heart rate data. It provides real-time heart rate, statistical prediction, and training zones shown in graph and text format.

### Can I use Cardio Zones without a heart rate sensor?

Yes, if you do not have a Bluetooth heart sensor or Apple Watch, Cardio Zones can still help you calculate your VO2 Max, maximum heart rate, and get optimal heart zones based on your fitness goals.

### How often is Cardio Zones updated?

The latest version is 4.7.0, last updated on December 2, 2025. This indicates regular updates to improve functionality and support.

### What are the privacy features of Cardio Zones?

Cardio Zones prioritizes user privacy. No login account or external web accounts are required, and your data remains private. You keep your data, and no subscriptions are needed.

### What age rating does Cardio Zones have?

Cardio Zones has an age rating of 12+. This suggests it is suitable for users aged 12 and above.

### What training zone formulas does Cardio Zones use?

Cardio Zones comes with preloaded heart rate training zones using formulas like Karvonen & Zoladz, British Cycling Coaches, and Joe Friel Running & Cycle. You can also create your own bespoke heart rate zones.

## Version history (last 5 releases)

### 4.7.0 — 2025-12-02

- Update for iOS 15.6 - 26, watchOS 8.7 - 26
- added support for multi-window, where applicable (iPad)
- Add ability to pair a heart rate monitor persistently (iPhone/iPad devices)
- Improved compatibility with Apple Health.

### 4.6.3 — 2023-03-30

Fix crash for runners on Apple Watch

### 4.6.2 — 2023-03-09

Added more support for stationary bikes using the Cycling Speed and Cadence Bluetooth service (Apple Watch only):
- Max, Min and average cadence during a workout will appear in workout reports and history.

### 4.6.1 — 2023-03-06

Added more support for stationary bikes using the Cycling Speed and Cadence Bluetooth service (Apple Watch only):
- Write wheel distance to Apple Health Cycling distance.

Pair your Schwinn Bike, or another Bluetooth bike sensor, via the app's Settings screen on your Apple Watch.

### 4.6.0 — 2023-03-02

We added support for stationary bikes using the Cycling Speed and Cadence Bluetooth service (Apple Watch only). Pair your Schwinn Bike now via the app's Settings screen on your Apple Watch.

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## More apps by Theo Scott

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- [Quiz on C++ Programming](https://appshunter.io/ios/app/quiz-on-c-plus-plus-programming/id1193577696)
- [VO2 Max Calculator](https://appshunter.io/ios/app/vo2-max-calculator/id1586812282)

All apps by Theo Scott: https://appshunter.io/developer/691156625

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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 2026-06-28.*