# Zone 2 AI: Vo2 Max & Endurance — Easy Pace Heart Rate Training > AI-powered Zone 2 and VO2 Max training for longevity and metabolic health. (iPhone/iPad app by Unbounded Technologies LLC.) - Source: https://appshunter.io/ios/app/zone-2-ai-vo2-max-and-endurance/id6742467259 (this page in markdown: same URL + `.md`) - Developer: [Unbounded Technologies LLC](https://appshunter.io/developer/1810608557) - Category: Health & Fitness, Lifestyle - Price: Free with in-app purchases - Rating: 4.50/5 from 118 App Store ratings · 33 written reviews indexed - Age rating: 4+ - Requires: iOS 17.6 · 84 MB - Languages: American English - Released: 2025-03-16 - Data updated: 2026-08-27 - Monetization: free with in-app purchases - User reviews in markdown: https://appshunter.io/ios/app/zone-2-ai-vo2-max-and-endurance/id6742467259/reviews.md ## What is Zone 2 AI? Build the Engine. Raise the Ceiling. Zone2AI is the complete longevity protocol. We combine steady-state Zone 2 training (to build mitochondrial efficiency) with the science-backed Norwegian 4x4 Sprint Protocol (to maximize VO2 Max). Whether you follow Peter Attia, Andrew Huberman, or Inigo San-Millán, you know that "exercise is the most potent longevity drug." Zone2AI is the only app that prescribes the exact dosage, validates your effort, and projects your future health. INTRODUCING ZONE2AI 2.0 - RPE Feedback: "Rate of Perceived Effort" after every workout, means that your Zone2Ai heart rate range gets better and better every time you use it. Finally, a Zone 2 training app that gets smarter every day. - The Sprint Protocol (Norwegian 4x4): Zone 2 builds the foundation; Sprints build the skyscraper. Unlock "Sprint Credits" by completing your Zone 2 base, then redeem them for guided High-Intensity Interval Training (HIIT) designed to spike your VO2 Max. - Zone2AI Power Score: Are you becoming more metabolically efficient? We calculate your unique Power Score (Watts/kg) to measure exactly how much power your body can generate while remaining in a fat-burning state. - The Path (Future You): Don't just track today; visualize tomorrow. See how your current training trajectory impacts your predicted biological age and VO₂ Max over the next decade. - Incline Calibration: Training on a treadmill? Our new calibration tool helps you find the perfect incline to hit your metabolic peak without running. From "Restoration" to "Performance," choose the path that fits your biological reality. We build a custom weekly prescription based on your age, gender, and resting heart rate. CORE FEATURES - True Zone 2 Validation: We don't just log minutes. We filter your Apple Health data to find *actual* Zone 2 sessions: steady-state cardio in your personal biosignal range, sustained for as long as your personalized plan calls for. No false positives. - Apple Watch Haptics: Stay in the zone without looking at your wrist. Get subtle, real-time haptic feedback when you drift out of your target range during Zone 2 or Sprint sessions. - The Weekly Dose: Track your progress toward the ideal scientific benchmark of 180–240 minutes/week. - Total Privacy: No ads. No selling data. We use on-device logic and anonymized processing to generate your insights. Your biological data belongs to you. - Universal Sync: Works with your Apple Watch, Polar, Garmin, Strava, WHOOP: anything that writes workouts to Apple Health. Zone2AI is built for anyone seeking to build a real zone 2 habit. From beginners to high-performance individuals: biohackers, endurance athletes, and anyone optimizing for mitochondrial health and longevity. This is not a general fitness tracker. This is a precision tool for a longer life. Train in Zone 2. Sprint for VO2 Max. Defy your age. Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ ## Key features - Personalized Zone 2 training guidance - Norwegian 4x4 Sprint Protocol - Rate of Perceived Effort (RPE) feedback - Zone2AI Power Score calculation - Projected biological age and VO2 Max - Apple Watch haptic feedback - Syncs with Apple Health and other wearables ## Pricing and in-app purchases Base price: Free. **Subscriptions** | Subscription | Price | Period | | --- | --- | --- | | Unlimited Access | $24.99 | per year | | Unlimited Access | $3.99 | per 7 days | | Zone2AI Pro Six Months | $17.99 | per 6 months | | Weekly Premium Access | $3.99 | per 7 days | | Unlimited Premium Annual Access | $24.99 | per year | **One-time purchases** | Purchase | Price | Type | | --- | --- | --- | | Lifetime | $39.99 | one-time | | Premium Lifetime | $39.99 | one-time | | Lifetime | $24.99 | one-time | | Lifetime Unlimited Premium | $24.99 | one-time | ## Recent user reviews (10 of 33) All indexed reviews: https://appshunter.io/ios/app/zone-2-ai-vo2-max-and-endurance/id6742467259/reviews.md ### 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 ### 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. ### 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 ### 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 ### 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 ## Frequently asked questions about Zone 2 AI ### What does Zone 2 AI do? Zone 2 AI provides a complete longevity protocol by combining steady-state Zone 2 training for mitochondrial efficiency with the Norwegian 4x4 Sprint Protocol to maximize VO2 Max. It offers personalized weekly prescriptions based on your biological data and validates your effort to project future health. ### What are the key features of Zone 2 AI? Key features include RPE feedback to improve heart rate ranges, the Sprint Protocol for VO2 Max enhancement, a Zone2AI Power Score to measure metabolic efficiency, future health projections, and incline calibration for treadmill training. It also offers true Zone 2 validation and Apple Watch haptics. ### How much does Zone 2 AI cost? The app is available for free with in-app purchases. Specific pricing details for premium features or subscriptions are not detailed in the provided description, but the core functionality is accessible. ### What devices is Zone 2 AI compatible with? Zone 2 AI works with Apple Watch and syncs with Apple Health. It also integrates with other popular fitness trackers like Polar, Garmin, Strava, and WHOOP, as long as they write workout data to Apple Health. ### Who is Zone 2 AI for? This app is designed for anyone seeking to build a consistent Zone 2 training habit, from beginners to high-performance individuals. It's ideal for biohackers, endurance athletes, and anyone optimizing for mitochondrial health and longevity. ## Version history (last 5 releases) ### 2.4.9 — 2026-08-27 Zone2AI keeps leveling up — here's what's new on your path to a stronger heart: • Your celebration waits for you: finish a session on your watch, then open your phone whenever suits you — that evening, the next morning — and the moment is still there, ready to play. • A calmer, sharper Zone2AI: one typeface across the whole app, consistent spacing and color on every screen, and buttons and cards that answer the instant you touch them. Movement that points you toward what comes next. • See exactly where you were: every session traces your heart rate against your personal Zone 2 band, so even a session that came up short shows you how close you got. • An evening wrap-up: one end-of-day summary of the Zone 2 minutes you banked, arriving when you can actually enjoy it. • We ask what to call you, and we use it. • Your Zone 2 range stays yours: personal and steady, whichever watch you train with — Apple Watch, Apple Watch Ultra, or Garmin with our companion watch app. • And the engine underneath keeps getting stronger: a Zone 2 verdict you can trust, an AI coach that ties your training to your recovery and your sleep, milestone celebrations with three completion tiers, and LEVEL 5 "APEX" for athletes whose old goal became their new minimum. Train easy. Get faster. Live longer. ### 2.4.8 — 2026-08-24 Zone2AI keeps leveling up — here's what's new on your path to a stronger heart: • The verdict you can trust: every workout gets a clear Zone 2 read — how long you stayed in your zone, what moved your personal range, and what to do next. Easy-pace training, made measurable. • Garmin athletes: the new watch app (v1.3.8) puts your whole workout on one screen — press STOP and continue, save, or discard with a single press each, with a two-step confirm so nothing is lost by accident. Mark laps instantly with BACK. • Celebrations that meet you at the door: goal-met cinematics, pyramid milestones with three completion tiers, and near-miss sprints that tell you exactly how close you came — now including workouts your phone analyzed while it sat in your pocket. • A coach that opens with a hook: short, shareable insights connecting your training to your recovery, your sleep, your life — screenshot-worthy by design. • The moment you finish: a notification with exactly how many Zone 2 minutes you just banked. • Your membership travels with you: reinstall or switch phones, and your access — and your smartwatch choice — are recognized on arrival. • LEVEL 5 "APEX" for elite athletes: 75-minute sessions where your old goal becomes your new minimum, and weekly goals that grow alongside you. Train easy. Get faster. Live longer. ### 2.4.7 — 2026-08-22 Zone2AI keeps levelling up — here's what's new on your path to a stronger heart: • LEVEL 5 "APEX": a new elite tier for athletes ready for 75-minute sessions. Your old goal becomes your new minimum, and your prescription grows with you. • Smarter weekly goals: your session goal and what banks credit are now two different numbers — so a solid shorter effort still counts towards your week while your full target keeps pulling you forward. • Your zone, explained: when your personal Zone 2 range shifts, the app now shows you a gentle shimmer and tells you exactly which body signals moved it. Your range has reasons — and now you can see them. • Ask your coach anything: heart-rate straps, watches, data sources — your AI coach now answers product questions instantly, right where you train. • Celebrations that earn the moment: pyramid milestones with three completion tiers, goal-met cinematics, and near-miss sprints that tell you exactly how close you came. • Garmin athletes: pair with the new Zone2AI watch app (v1.3.7) — miles or kilometres follow your phone everywhere, Level 5 goals show correctly on your wrist, and your phone now tells you the moment a watch update is ready. • Accuracy, sharpened: sleep totals now match Apple Health to the minute, zone minutes reflect exactly what your heart did, and if iPhone storage ever runs low enough to affect workout syncing, Zone2AI warns you before it matters. Train easy. Get faster. Live longer. ### 2.4.6 — 2026-08-16 Two months of building, and it all lands with this update. EVERY REAL SESSION EARNS SOMETHING Your daily goal is still the full dose that drives adaptation — and now there's a credit threshold underneath it. Clear that and the session banks toward your week, labeled honestly as a partial with the gap to your goal named. A shorter session that was genuinely hard now earns credit for being exactly that. Prefer all-or-nothing? Settings, Session Credit, Strict Mode. LEVEL 5: APEX A new tier above Elite, for athletes who have outgrown the ladder: 75-minute sessions, with a full Elite session as the bar to bank one. A COACH THAT READS YOUR BODY Your daily insight weighs your resting heart rate against your own baseline, your sleep, your heart-rate variability and your recent training — a morning read on what you are ready for today. It remembers what it has told you, rotates through genuinely different angles, and takes your thumbs up or down to learn your taste. AND NOW ONE THAT KNOWS THE PRODUCT Ask about chest straps, what makes a session scoreable, or how your watch reaches Zone2AI, and you get a real answer — or a straight "that one is outside what I can see" with a way to reach a human. The Zone 2 Guide gained a section on watches, straps and data, including why a chest strap is the more accurate instrument for Zone 2 specifically. CELEBRATIONS WORTH TRAINING FOR Your pyramid grows as the week builds, with a pulse, a glow and a haptic the moment a session lands. Closing out your week now has three distinct moments: GOLDEN FOUNDATION, SUMMIT STRIKE and ASCENSION. Share cards carry your heart-rate trace and your personal-record comparisons, ready the instant you want them. ON YOUR WRIST A quiet progress gauge sits beside your Zone 2 timer and fills toward your goal, with a small mark where your credit lands — cross it mid-session and your watch says so. Sessions are picked up in the background too, so training you did without thinking about us still finds its way in. ZONES THAT KEEP GETTING TRUER Your Zone 5 threshold is derived from your own Zone 2 ceiling, so easy days read as easy and sprints have to be earned. And when your range shifts as your resting heart rate and fitness change, the app points it out and your coach explains what moved. PLUS Sleep totals that handle overlapping sources, richer Garmin sync, average pace on the watch, and polish throughout. ### 2.4.5 — 2026-08-10 Zone2AI keeps getting better, and finishing your pyramid is now an EVENT. FINISH THE PYRAMID, GET THE SHOW Hit your weekly Zone 2 goal and gold floods the base of your pyramid. Complete your sprint goal and the summit ignites. Do BOTH and you get Ascension — our most beautiful celebration: the lights drop, your pyramid ignites edge to edge, and gold rains from the peak. You earned it; the app should act like it. A COACH THAT EARNS ITS PLACE Insights rotate across 20 topic families, learn from your thumbs up/down, and you can ask a follow-up right from any insight card. POLISH EVERYWHERE Celebrations survive slow data and interruptions, progress screens are dependable, your saved birthday stays recognized, Zone 5 detection is sharper than ever, and this update adds dozens of small refinements. Thank you for the sharp reports — keep them coming from Settings → Send Feedback. ## Apps similar to Zone 2 AI | App | Rating | Price | Category | | --- | --- | --- | --- | | [Zone2Track](https://appshunter.io/ios/app/zone2track/id6451061206) | 4.4 (5) | Free | Health & Fitness | | [Cardiolytics: VO2 Max Health](https://appshunter.io/ios/app/cardiolytics-vo2-max-health/id6749484835) | 4.1 (17) | Free | Health & Fitness | | [Zolt: Energy and Macro Coach](https://appshunter.io/ios/app/zolt-energy-and-macro-coach/id6736639311) | 4.2 (61) | Free | Health & Fitness | | [Zone Trainer: Heart Rate Zones](https://appshunter.io/ios/app/zone-trainer-heart-rate-zones/id1660486485) | 4.9 (12) | Free | Health & Fitness | | [Zone2 Fitness](https://appshunter.io/ios/app/zone2-fitness/id6444166065) | 5.0 (1) | Free | Health & Fitness | | [Zone 2: Heart Rate Training](https://appshunter.io/ios/app/zone-2-heart-rate-training/id6444690892) | 4.6 (239) | Free | Health & Fitness | ## More apps by Unbounded Technologies LLC - [Couple App: Get Closer](https://appshunter.io/ios/app/couple-app-get-closer/id6752629330) All apps by Unbounded Technologies LLC: https://appshunter.io/developer/1810608557 ## Related topics [zone 2 ai](https://appshunter.io/ios/topics/zone-2-ai) · [in the zone by camino coaching](https://appshunter.io/ios/topics/in-the-zone-by-camino-coaching) · [zone 2](https://appshunter.io/ios/topics/zone-2) · [czone 2](https://appshunter.io/ios/topics/czone-2) · [vo2max training](https://appshunter.io/ios/topics/vo2max-training) · [endera](https://appshunter.io/ios/topics/endera) · [vo2max cardio & performance](https://appshunter.io/ios/topics/vo2max-cardio-performance) --- *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.*