# Peak Intervals — Guided 4x4 on Apple Watch

> Guided 4x4 on Apple Watch (iPhone/iPad app by Justin Polidori.)

- Source: https://appshunter.io/ios/app/peak-intervals/id6757667069 (this page in markdown: same URL + `.md`)
- Developer: [Justin Polidori](https://appshunter.io/developer/1866410754)
- Category: Health & Fitness
- Price: Free with in-app purchases
- Age rating: 17+
- Requires: iOS 26.0 · 13 MB
- Languages: American English, French (France), German (Germany), Italian, European Portuguese, European Spanish
- Released: 2026-02-05
- Data updated: 2026-08-16
- User reviews in markdown: https://appshunter.io/ios/app/peak-intervals/id6757667069/reviews.md

## What is Peak Intervals?

Peak Intervals helps you train VO₂max using the Norwegian 4x4 interval method and track training quality over time.

Run, ride, or row a 4x4 session, stay in your target heart rate zone, then review clear metrics that explain workout quality and progress over time.

What you get:
• Guided 4x4 workouts with Apple Watch support
• Target heart rate zone guidance based on 90–95% of estimated HRmax
• Time in Zone (≥90% HR) to measure intensity
• Repeatability to see if you hold performance from interval 1 to 4
• Recovery to measure how fast your heart rate drops between intervals
• Trends and simple verdicts like Improving, Stable, Under-target, or Fatigued
• Workout history with interval breakdowns and session details

Apple Health
Peak Intervals can read workout and heart rate data from Apple Health (HealthKit) to compute your metrics and trends. You control what is shared at any time in iOS Settings.

Subscriptions
Peak Intervals offers an auto-renewing subscription with monthly and yearly plans, including a 2-week free trial where available. After the trial, an active subscription is required to start new workouts. Payment is charged to your Apple ID account at confirmation of purchase. Subscriptions renew automatically unless canceled at least 24 hours before the end of the current period. You can manage or cancel your subscription in App Store account settings.

Peak Intervals is not a medical device and does not provide medical advice. High-intensity exercise may not be appropriate for everyone. Consult a physician before beginning a new training program.

Privacy Policy: https://peakintervals.app/privacy
Terms of Use: https://peakintervals.app/terms

## Pricing and in-app purchases

Base price: Free.

**Subscriptions**

| Subscription | Price | Period |
| --- | --- | --- |
| Pro | $9.99 | per month |
| Pro Yearly | $49.99 | per year |



## Version history (last 5 releases)

### 1.2.5 — 2026-08-12

just bugfixing

### 1.2.4 — 2026-07-06

New Trends tab to track your progress over time, plus improved treadmill run accuracy by preventing rare distance spikes from affecting interval results.

### 1.2.3 — 2026-03-25

We’ve improved onboarding to make Peak Intervals easier to get started with, including clearer guidance for Apple Watch setup, a better explanation of workout analytics and progress tracking, and a smoother path for athletes using iPhone only.

This update also improves sign-in and account creation with better email/password handling and smarter password autofill support. On Apple Watch, live workout guidance is now more reliable, with clearer heart rate target feedback and improved syncing of workout state and metrics.

### 1.2.2 — 2026-03-21

- Refined the latest workout summary with cleaner stats, better alignment, and clearer interval insights.
- Improved Apple Watch workout start reliability.
- This update makes subscription sync between iPhone and Apple Watch much clearer and more reliable. If the watch can’t verify Pro access right away, you’ll now see guided recovery steps instead of a generic error.

### 1.2.1 — 2026-03-17

Bugfixes and enhancements

## Apps similar to Peak Intervals

| App | Rating | Price | Category |
| --- | --- | --- | --- |
| [Ramp4x4: VO2 Max Trainer](https://appshunter.io/ios/app/ramp4x4-vo2-max-trainer/id6768789400) | — | Free | Health & Fitness |
| [WiserQuote](https://appshunter.io/ios/app/wiserquote/id6755392260) | 5.0 (1) | Free | Health & Fitness |
| [Pulse: Interval Timer](https://appshunter.io/ios/app/pulse-interval-timer/id6761445290) | — | Free | Health & Fitness |
| [VO2Pro: HIIT Trainer](https://appshunter.io/ios/app/vo2pro-hiit-trainer/id6780353919) | 5.0 (1) | Free | Health & Fitness |
| [Norwegian 4x4 Coach](https://appshunter.io/ios/app/norwegian-4x4-coach/id6782398289) | — | Free | Health & Fitness |
| [Stellar Intervals](https://appshunter.io/ios/app/stellar-intervals/id6774685576) | — | Free | Health & Fitness |

## More apps by Justin Polidori

- [Trainwise IQ](https://appshunter.io/ios/app/trainwise-iq/id6757368895)

All apps by Justin Polidori: https://appshunter.io/developer/1866410754

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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 2026-08-16.*