# Zone 2 AI: Vo2 Max & Endurance — user reviews

> 33 indexed App Store user reviews of Zone 2 AI by Unbounded Technologies LLC, rated 4.50/5 from 118 ratings.

- Source: https://appshunter.io/ios/app/zone-2-ai-vo2-max-and-endurance/id6742467259/reviews
- App overview in markdown: https://appshunter.io/ios/app/zone-2-ai-vo2-max-and-endurance/id6742467259.md
- Rating breakdown: 5★ 91 · 4★ 12 · 3★ 5 · 2★ 3 · 1★ 7

## Newest reviews (10 of 33)

### 4/5 — Not Attia’s Zone 2

*2025-08-29*

Conceptually, I like this app. But it’s suggesting that I work out above my lab-measured lactate threshold and there’s no way for me to adjust so the metrics. My lactic threshold is 118 bpm but the app recommends 113 to 125 BPM to reap the benefits of Attia’s Zone 2 training. Five stars if I could set my own lactate threshold in the app.

**Developer response:** Thanks for the thoughtful review, and for sharing your lab-measured lactate threshold data (the holy grail of zone 2 data). That level of precision shows you're serious about getting Z2 right, and we respect that.

You're absolutely correct: while the app currently calculates your range using age, max HR, and 30-day resting HR average, it doesn’t yet allow users to manually input a lab-tested LT1 (lactate threshold). That’s a feature we agree is important for more advanced users, and it’s on our roadmap.

We recommend trying our Apple Watch companion app, which makes it easier to stay aware of your live Zone 2 minutes during a workout. And we’ll keep you posted as we build out the ability to fully personalize ranges, including by setting your own lactate threshold.

Thanks for using Zone2AI and helping us improve. this kind of feedback pushes us forward.

best, 
Rod & Zone2Ai team

### 5/5 — Very funny

*2025-05-22*

Love the snarky remarks. Makes me want to workout just to see what it says.

### 5/5 — Keeps me honest

*2025-05-15*

Always make sure I can block in at least 45 mins of “true zone 2” now and the effects on my VO2 max are impressive. The app forces me to do workouts that stick to the science and maximize heart benefits.

### 5/5 — Very Intuitive

*2025-04-21*

Very intuitive. Connects to my Apple Watch and gets the workout info seamlessly. Insights opened my eyes to how some of my workouts are not really Zone 2!

**Developer response:** That realisation is the reason the app exists. Most people are training harder than Zone 2 and getting less from it than they think.

Rod, Founder of Zone2AI

### 5/5 — Excelente app

*2025-04-19, version 1.0.1*

Muy práctica para mi ejercicio Zone 2 según Peter Attia.

### 5/5 — 5 Stars - Game Changer for My Fitness Journey!

*2025-04-16*

Zone 2 AI has completely transformed the way I train. I’ve always struggled with staying in the right heart rate zone during my cardio sessions, but this app makes it so easy and effective. The AI-driven insights are incredibly accurate and personalized — it feels like having a virtual coach right in my pocket.

What I love the most is how intuitive the interface is. It tracks my progress, adjusts to my fitness level, and keeps me motivated with real-time feedback. I’ve noticed major improvements in my endurance, fat-burning efficiency, and overall performance.

If you’re serious about optimizing your training and want an app that’s both smart and supportive, Zone 2 AI is a must-have. This isn’t just another fitness app — it’s a total game changer!

**Developer response:** Thank you. The coach reads your actual sessions rather than a template, which is why it occasionally tells you something you didn't want to hear.

Rod, Founder of Zone2AI

### 5/5 — Game changer

*2025-04-04*

I have been looking for an app that does exactly this. The UX is super intuitive and the stats are perfect for my zone 2 tracking. I don’t know why it has taken so long for this to come out because it is a game changer. Kudos to the creator!

**Developer response:** I asked myself the same question, which is roughly why it exists. Thank you.

Rod, Founder of Zone2AI

### 5/5 — Streamlined

*2025-03-20*

Love not having to track my weekly zone 2 minutes in Notes anymore. Zone2ai makes the tracking seamless and keeps me motivated to hit my weekly goal.

### 5/5 — Excellent and accurate

*2025-03-18*

for anyone looking to better track their zone 2 longevity goals, this is the app!

**Developer response:** Thank you. Longevity is the long game, and Zone 2 is the least glamorous part of it.

Rod, Founder of Zone2AI

### 5/5 — Great app!

*2025-03-18*

So easy to use

## Most critical reviews (10 lowest-rated)

### 1/5 — Unacceptable Data Loss: Unstable Third-Party Software

*2026-08-19*

I paid for this app expecting reliable Zone 2 tracking on my Garmin Venu 3S. Because Garmin’s operating system only allows one active tracking application at a time, choosing Zone 2 AI means you must completely bypass Garmin’s native, stable activity profiles. You are forced to entrust your entire session to this third-party software.
That trust is misplaced. After completing a strictly controlled 36-minute workout and tagging it as 'Other' upon saving, the app suffered a critical crash. It completely failed to write the .FIT file to the watch's hard drive, permanently deleting the session.
This is not a minor software glitch; it is the outright destruction of a valuable, well-performed workout. The permanent loss of these specific cardiovascular parameters actively corrupts the physiological data required to accurately evaluate progress and structure future training patterns.
Do not pay for software that jeopardizes your data integrity. You can achieve the exact same physiological targeting securely by setting custom High/Low Heart Rate alerts directly within Garmin’s native, crash-proof activity profiles.

**Developer response:** Updating this, because part of what I wrote here is no longer true.

The "Other" activity type that destroyed this session is gone, and that specific failure cannot recur. But I said saving was reliable, and it was not something I could stand behind. A later session on the same watch model was lost a different way.

What changed since: the watch app no longer pushes any menu over a live recording, and that component was present in every reproduction we have. Stopping and discarding now happen on the workout screen itself, with two presses required to throw a session away.

I am not calling this closed. It stays open on our side until the field data says the failure has stopped, and one scenario is still untested. That is the honest state of it.

Rod, Founder of Zone2AI

### 1/5 — Apple Watch Series 3

*2026-06-22*

I have been saying to start targeting my heart health more. I life 5 days a week and I am I great fiscal shape but I know I need to working more on my heart health. 

I have been hearing about Zone 2 triangle for some time and want to integrate that into my training program

I found the app last night and it seems to be perfect I downloaded it, set it up on my iPhone but it’s not on the Apple Watch.. now I know my series 3 is a bit old but I would assume it would work… 

I tied to get help using the AI tool in the app and it does not work for helping with the app..

I searched in line and there’s little to now help. 

I did find a posthaste app will not work on a series 3..

It seems to be more effort than it’s worth.. apps do not need to be this complicated.. it should be like any other app.. download set up then use.. 

I purchased the lifetime subscription for something it seems will not work.

**Developer response:** Hi Bill, thank you for the review, and for wanting to build the Zone 2 base. Helping people like you is why the app exists. Let me clear up the watch part, because the core of what you bought does work for you.

The Zone2AI watch app needs a newer watchOS than the Series 3 can run, so it will not appear on that watch. That is a real limit of the older hardware, not something setup can fix. But you do not need our watch app to get your Zone 2 heart range and build your habit. Record your run or walk with the built-in Apple Workout app on your Series 3, then open Zone2AI on your iPhone. It reads that workout from Apple Health and gives you your time in Zone 2, the triangle, all of it.

The in-app coach answers training questions, so for setup it is faster to email me directly at support@zone2ai.com and I will get you going personally. 

Best, 
Rod, 
Founder of Zone2AI

### 1/5 — Where is the free trial?

*2026-05-31*

I will not blindly pay for something without trying first. Deleted the second I got to the subscription page.

**Developer response:** Hi Richie, i understand that you do not want to pay blindly for something you haven't tried, and i respect that.

We don't have a traditional free trial right now, but we do have a low-cost weekly option ($2) specifically so you can test the full app without a major commitment. If it's not for you, you can easily request a refund through Apple.

I built this to be a tool you genuinely value, which is why we also offer a one-time Lifetime license so you can just own it forever with no recurring billing. If you're open to giving it another look, I'd love the chance to win you over. Please reach out to me directly at support@zone2ai.com.

Best,
Rod, Founder Zone2Ai

### 1/5 — Older version was better

*2026-01-07*

The older version was much easier to use. This new version is very busy and confusing. I’ll stick with though so long as it stops seeing all my workouts as runs. Still think the older version was much better and easier to use. Simple and Clean.

**Developer response:** Hi Drewjames, thank you for being a long-time user. I appreciate you sticking with us through the transition to v2.0.

We hear your feedback about the app "seeing all workouts as runs." In the next update, if you record a non-cardio workout (like Strength Training or Yoga), the app will no longer assume it's a Zone 2 attempt. It will simply ask: 'Was this a Zone 2 session?' If you say 'No', it just logs it quietly without the confusing analysis screen.

We are also building a "Minimalist Mode" to bring back the clean, simple experience you loved from v1, tailored to zone 2 enthusiasts.

Thanks for the honest feedback. it helps us make the app better.

Ro & the Zone2ai Team

### 1/5 — Aggravating

*2025-10-18*

Most aggravating app ever invented. After the app glitched, I deleted and reloaded. Then “Sign in here” link does not work so the only way to login again is to pay again. Additionally, the app offers zero feedback or support unless you reach the 45 minute threshold required. For someone training for a marathon or half marathon or even just trying to increase their Zone 2 Threshold, that’s maddening. As a personal trainer with 25 years experience, I could never recommend this to my clients. Highly disappointing in this day and age.

**Developer response:** I hear you. Your experience sounds incredibly frustrating, and I’m sorry it happened. You’re right: no one should ever have to pay twice just to log back in. Please go ahead and request a refund through Apple, and we’ll make sure it’s approved as soon as possible.

Zone2AI is currently geared toward Zone 2 enthusiasts who want a precise tool to guide them to their ideal heart-rate range. But we’re evolving fast: our goal is to make it a tool that helps anyone build a sustainable Zone 2 habit for life, no matter where they’re starting from.

We’re also adding real-time feedback and smoother progress tracking so users can see value even before they're able to hit the 45-minute threshold.

As a trainer with 25 years of experience, your feedback is gold. We'd love to connect directly at support@zone2ai.com if you’re open to sharing more.

Thanks again for calling this out. It helps us improve.

Rod & the Zone2AI team

### 2/5 — Limitations

*2026-05-21*

I have multiple tracking apps that I use to track my runs, they track elevation gains time in different zones and I like to use my Apple Watch Workouts to track my runs, no matter how hard I stay in the zone 2 range, it never counts as zone 2 according to this app so I’m disappointed but ditching it. To use this app solely isn’t gonna happen especially since I can’t run vem see all my run histories on this app. You say for accuracy use this app but with all the limitations I rather not. Also I feel that this zone 2 goes all the way to tempo pace for me.

**Developer response:** Hi Itsmeyuli,

Thank you for taking the time to write this. You highlighted some real points of friction, and I want to help clear them up.

On your Zone 2 range extending into tempo pace. The app has a built-in way to adjust this using the RPE prompt at the end of your sessions: after each workout, you can mark Too Easy, Just Right, or Too Hard. The system combines your physiology with your lived workout experience: every Too Hard you submit lowers the range. If your sessions feel like they are extending into tempo pace, marking Too Hard for the next few will automatically pull the range back down to where it belongs.

On seeing all your run histories: You can find these in the Week tab on the home screen, which shows every workout the app reads, not just the Zone-qualified ones. Zone 2 sessions appear at the top, sprints in their own row, and everything else lands under "Other Workouts" further down. That is the best place to verify your runs are being seen by the app. Those that qualify show up as Zone 2 or Sprints, and the rest are still safely recorded there.

On Apple Watch Workouts not counting as Zone 2 even when your heart rate sits in the range. Our detection on HealthKit-imported workouts is stricter than it should be, which is a real limitation we are working to improve. Today, the cleanest way to get precise Zone 2 tracking is to use the Zone2AI watch app directly on your Apple Watch, which runs the calculation live in your personalized range and surfaces the credit immediately.

It would be great if you reach out at support@zone2ai.com so I can look at your numbers and help calibrate sooner.

I would love it if you try Zone2AI's watch app on your next run, give honest RPE feedback at the end, and let me know how it feels.

Best, Rod
Zone2AI

### 3/5 — Many noticable glitches

*2026-06-17*

The app freezes during mirroring in sprint session.  It mentions the norwegian 4x4, but there is no clear way to log it.  The coaching insights often give false info, as if a person hasn’t done a session.  These are just a few things.  It definitely needs to be revamped

**Developer response:** Hi Amazinace, and thank you. This feedback makes the app better. I appreciate you taking the time to write it out.

You flagged three real things, and I want to own each. A freeze during a sprint session is on us; the heaviest moment is right as an intense workout finishes and syncs in, and I want to find exactly where it is catching for you. 

You are also right that the Norwegian 4x4 is not as clear or as easy to start as it should be. We built that protocol carefully and have not yet brought it into every part of the experience, and making it obvious is on my to-do list. Finally, a coaching insight that reads as if you have not trained almost always means your latest session didn't sync on time, which we have been steadily fixing and clearly have not fully solved.

I read every message myself. Tell me which watch you train with and I will get to the bottom of all three with you. Please email me at support@zone2ai.com. I want to earn those stars back.

Best,
Rod, 
Founder of Zone2AI

### 3/5 — Has a lot of potential

*2026-06-01*

Love the concept of this app, it’s just pretty buggy. It doesn’t accurately track your workouts, I’m primarily using this for the zone 2 heart rate indicator.

**Developer response:** Hi Tim, thank you for the feedback, and for rooting for us. Love to hear that you like the core concept and the live Zone 2 indicator.

You're right that workout tracking has had some bugs on some Garmin watches, but we've recently shipped a string of updates aimed at fixing exactly this. I'd love to get your specific setup tracking perfectly.

Could you email me directly at support@zone2ai.com? I read every message and will work with you personally to get your data logging accurately every single time. I want to earn those extra stars!

Best, Rod

### 3/5 — Too literal

*2025-09-09*

All this app really does is screen your workouts for any that meet its very strict definition for zone 2 and then provide you with some AI babble to go along with it. 

My main complaint is that if you do a 50-55 minute steady state workout with an average HR in the dead center of your zone 2 range, it likely won’t count as it usually takes a few minutes at the beginning to ramp up to your target range and if there is any noise in your HR data (common with wrist mounted monitors like Apple Watch, garmin, etc) you won’t end up with the minimum 45 minutes in range that it requires. Also, if there is a way to customize the Zone 2 HR range, I couldn’t find it.

**Developer response:** Thanks for the feedback. We hear you.

Zone2AI uses a rigorous definition of Zone 2 because the research (including from Dr. Peter Attia) shows that you need at least 45 continuous minutes in your true Zone 2 to unlock the full mitochondrial and metabolic benefits. Were not strict for the sake of it; we do it to helping you hit the threshold that matters for long-term health and performance.

We understand your frustration. Especially when ramp-up time makes it hard to get credit for the work you’re doing. We're actively working on ways to make the experience more friendly while staying true to the science.

We invite you to try our Zone2AI Apple Watch companion app, which shows you in real time how many minutes you've logged in valid Zone 2. That way, there's no guesswork, and you’ll know exactly when you’ve hit that 45-minute mark.

Our next release will include the ability to customize the HR range, and guidance on incorporating Zone 5 / VO2 max sessions, which help you unlock the full benefits of the aerobic training "pyramid"

Thanks again for your support and for being part of this early journey. We're building Zone2AI to be the simplest, smartest way to train for health and longevity. Your feedback helps us get there.

### 4/5 — I want to like this app

*2026-05-06*

The developers of this app are super engaged and seem committed to taking feedback from customers to improve the app. I’ll continue using it as they work to smooth outs the kinks. I see a lot of promise in what they are working to achieve. It it's been clunky to get up and running. I use a Garmin tactics and a Whoop band and apparently the app does not import data directly from Garmin. It seems to wait for it to pass through Apple Health. I could be wrong on that but regardless it's difficult.

I believe they are going to figure it out. Rod has been very responsive via email.

**Developer response:** Hi Conrad, thank you for writing this. The 59-min ruck that didn't save and the "resume from earlier time" prompt both trace to a Garmin pause/resume bug we shipped a fix for on May 4 (Connect IQ v1.3.3.7). Three users hit it the same week, and your case helped us prioritize the bug fix. We've processed your refund given your troubles. 

Once you've tried the new version, I'd be grateful if you'd take another look at the rating. Either way, the refund stands.

Best, Rod

## Most praised reviews (10 highest-rated)

### 5/5 — Overall great stuff

*2026-08-17*

Overall really good app. I went 15:49 in Colorado at elevation in the 5k recently off of CONSISTENT use of this app when I was in base training phase this summer. It helped me focus directly on my heart rate vs pace directly. There is a payment but I recommend getting the lifetime version because you’re going to START seeing results after about 3ish weeks. It takes time and consistency to start seeing training benefits. All in all this app has been a game changer in the way I look at easy runs. Hopefully I can go sub 15:30 in Colorado this year as a high school junior!!🤞🔥

**Developer response:** The three-weeks line is the most useful thing anyone has written about this app, and it changed how I explain it to people. Zone 2 gives you almost nothing on day one, which is exactly why most people quit before it starts working. Congratulations on the 15:49.

Rod, Founder of Zone2AI

### 5/5 — Responsive developer and solid product

*2026-08-17*

The application offers a lot that is not easily found elsewhere.  What sets it apart is the developer is immediately responsive to questions or considerations for changes.  It works very well and much of the way it works is highly customizable, which is likely from responses to customers.  I use it multiple times per week and it has provided valuable insights to my training planning and execution.

**Developer response:** Thank you. You've named the thing I care most about getting right: most of what's customisable in here exists because somebody wrote in and asked. If you ever hit something that doesn't work the way you'd expect, email me directly and it'll get looked at the same day.

Rod, Founder of Zone2AI

### 5/5 — Great UI

*2026-08-14*

This is a beautiful designed app and is extremely helpful for creating a good routine while being easy to use and nice to look at.

**Developer response:** Thank you. The routine part is the harder half, so I'm glad that's the bit that landed. Zone 2 only works if it's easy to keep doing.

Rod, Founder of Zone2AI

### 5/5 — Amazing App!

*2026-07-31*

I was thrilled to find an app that was all about Zone 2 training. I wear a Garmin and tracking data definitely helps me stay motivated. This app is motivating and keeps me accountable and that’s exactly what a fitness app should do. The developer of this app cares about it working well. He is very responsive to questions. The app works seamlessly with my Garmin and I’m looking forward to any other perks he adds to it. Btw, since I have been using the app, my resting heart rate dropped and my hrv increased. Super happy!

**Developer response:** Kathleen, thank you. You did the training; we just kept score and nudged you to hold the zone. Zone 2 is the entire point of this app rather than one tab buried behind nine others, and Garmin is where most of our work goes. If anything ever looks off, email me and I will dig into it personally.

Best, Rod. Founder of Zone2AI

### 5/5 — So good

*2026-07-03*

Takes the guess work out.

**Developer response:** Thank you, this is exactly what we hoped to build: no guesswork, just train and trust it. 

I hope you enjoy every Zone 2 mile. Best, Rod.

### 5/5 — Great app to increase your performance

*2026-04-17*

I’ve been using zone 2 AI: VO2 max & endurance for a month and I’ve gain some aerobic endurance already. I will continue to use it so I can start improving my pace and zone 2

**Developer response:** Thanks Luisjo, hearing that you've built up aerobic endurance over a month is the exact signal that makes this worth doing. Keep showing up and the zone gets wider. Appreciate you sharing.

### 5/5 — Great insights

*2025-12-30*

Used the app a handful of times but I already like the insights I am getting and will be using it this year as I progress through my wellness journey.

**Developer response:** Thank you very much Brian! Glad the insights are helping you in your journey. That's exactly our goal: help people build the habit that leads to a long and high-quality life. 

Best of luck, and happy 2026!

### 5/5 — Love this

*2025-12-28*

Best app for zone 2. The incline adjustment works great. My vo2 max increased 2 points in 30 days.

### 5/5 — Can’t contact developer

*2025-10-03, version 1.2.1*

The developer’s website has no way to contact them, so I’m leaving a question in a review. 

I’m comparing this app’s zone 2 calculation (128-141bpm) to the Maffetone Method based on my age and being relatively untrained (180 - 49 - 5 = 126 max). 

If anything, I’ve read that the MAF calculations typically result in a _higher_ heart rate than most Zone 2 calculations, so I’m curious, how is this app determining the Zone 2 range?

My other issues have to do with the difficulty in meeting the 45 minute threshold, noise from heart rate monitoring, and lack of customization - but I’ve read the other reviews and appreciate the developer’s responsiveness on these points.

I can recommend this app with some reservations, and I’m looking forward to the updates.

### 5/5 — Very useful!!!

*2025-07-27*

Love this app!

---

*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 2026-08-27.*