# Heart Rate Zones: Underdog — Zone 2 Training & Leagues

> Zone 2 Training & Leagues (iPhone/iPad app by Ignas Velza.)

- Source: https://appshunter.io/ios/app/heart-rate-zones-underdog/id6758392759 (this page in markdown: same URL + `.md`)
- Developer: [Ignas Velza](https://appshunter.io/developer/1679188008)
- Category: Health & Fitness, Sports
- Price: Free with in-app purchases
- Age rating: 4+
- Requires: iOS 26.0 · 24 MB
- Languages: American English
- Released: 2026-03-03
- Data updated: 2026-09-03
- User reviews in markdown: https://appshunter.io/ios/app/heart-rate-zones-underdog/id6758392759/reviews.md

## What is Heart Rate Zones?

Underdog turns your Apple Watch heart rate data into a game. Every minute you spend in Zone 2 — the sweet spot for endurance and fat burning — earns you points. Compete in weekly leagues with friends and climb from Bronze to Diamond.

No manual logging. No ads. Just open the app once and your workouts sync automatically from Apple Health.

WHY ZONE 2?
Zone 2 training (60–70% of your max heart rate) is the foundation of every elite endurance program. It builds your aerobic base, improves VO2 max, and burns fat — without burning you out. The catch: most people train too hard to actually be in Zone 2. Underdog shows you exactly when you're in the zone.

FEATURES
* Automatic Apple Watch sync — workouts appear in seconds
* 5 heart rate zones (Z1–Z5) calibrated to your max HR
* Weekly leagues: Bronze, Silver, Gold, Platinum, Diamond
* Points for every Zone 2+ minute
* Achievements, streaks, and personal records
* Friend leagues — invite via link
* VO2 max tracking from Apple Health
* Works with running, cycling, rowing, hiking, and 40+ workout types

FREE
Underdog is free to use. Optional Underdog Pro unlocks unlimited friend leagues, advanced stats, and custom zones.

TERMS & PRIVACY
Terms of Use (EULA): https://tryunderdog.com/terms
Privacy Policy: https://tryunderdog.com/privacy

Subscriptions auto-renew unless cancelled 24 hours before the end of the current period. Manage in Settings → Apple ID → Subscriptions.

## Pricing and in-app purchases

Base price: Free.

**Subscriptions**

| Subscription | Price | Period |
| --- | --- | --- |
| Premium (Annual) | $29.99 | per year |
| Premium (Weekly) | $2.99 | per 7 days |

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| Premium (Lifetime) | $99.99 | one-time |



## Version history (last 5 releases)

### 1.6 — 2026-08-18

- Various fixes and improvements

### 1.5 — 2026-06-10

- UX fixes and improvements

### 1.4 — 2026-06-04

- Performance age
- User onboarding
- Weight tracking

### 1.3 — 2026-04-02

- Widget for quick league stats
- Privacy settings for public profile data
- Controls to view 7-day, 30-day, and 6-month data in select charts
- New charts (steps, resting heart rate, and more)
- Respiratory rate widget

### 1.2 — 2026-03-30

- Added in-depth analytics for Effort, Sleep, and Recovery
- Active Day can now be achieved with 20 active minutes or by walking 5,000 steps
- Chart visualisations improved for readability and consistency

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## More apps by Ignas Velza

- [PixelFixer - AI photo editor](https://appshunter.io/ios/app/pixelfixer-ai-photo-editor/id6446804863)
- [Worlds of Words](https://appshunter.io/ios/app/worlds-of-words/id6455940842)

All apps by Ignas Velza: https://appshunter.io/developer/1679188008

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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 2026-09-03.*