# Peak Intervals

> Guided 4x4 on Apple Watch

Canonical page: [https://chrome-stats.com/d/id6757667069](https://chrome-stats.com/d/id6757667069)

## Overview

- **ID:** `id6757667069`
- **Platform:** Apple
- **Type:** Apple app
- **Status:** Available
- **Publisher:** Justin Polidori
- **Category:** Health & Fitness
- **Version:** 1.2.8
- **Last updated:** 2026-09-20
- **First published:** 2026-02-05
- **Size:** 13 MB
- **Data as of:** 2026-09-22
- **Store listing:** [Apple App Store](https://apps.apple.com/us/app/peak-intervals/id6757667069)
- **Privacy policy:** [https://peakintervals.app/privacy](https://peakintervals.app/privacy)

## Description

Train VO₂max with Norwegian 4x4 intervals. Guided workouts, Apple Watch support, and clear analytics for time-in-zone, recovery, repeatability, and training progress.

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

## Rankings

- #1,755,586 — Overall

## Similar extensions and apps

- [Ramp4x4: VO2 Max Trainer](https://chrome-stats.com/d/id6768789400)
- [Norwegian 4x4 workout](https://chrome-stats.com/d/id6762572409) — 5.00 / 5
- [Crescendo 4x4: Norwegian HIIT](https://chrome-stats.com/d/id6791945508)
- [Z2/4×4 Trainer](https://chrome-stats.com/d/id6776864990)
- [Four by Four (fa7b3d)](https://chrome-stats.com/d/id6766068267)
- [Tabata & HIIT Timer - PEAKVO2](https://chrome-stats.com/d/id6532617265) — 5.00 / 5
- [Norwegian 4x4 Protocol: Boreas](https://chrome-stats.com/d/id6751464534) — 4.80 / 5
- [Intervals - the training timer](https://chrome-stats.com/d/id6736897379) — 4.00 / 5
- [Norwegian 4x4 Coach](https://chrome-stats.com/d/id6782398289) — 5.00 / 5
- [Norwegian 4x4 HIIT - Myworkout](https://chrome-stats.com/d/id6497329690) — 4.70 / 5
- [HeartOxy](https://chrome-stats.com/d/id6757838240)
- [VO2 Flow: Norwegian 4x4 Timer](https://chrome-stats.com/d/id6757104585) — 5.00 / 5

---

Source: [Chrome-Stats](https://chrome-stats.com/d/id6757667069)