# Crescendo 4x4: Norwegian HIIT — VO2 max interval timer, 30 sec

> VO2 max interval timer, 30 sec (iPhone/iPad app by KRZYSZTOF ANDRZEJ OTRZASEK.)

- Source: https://appshunter.io/ios/app/crescendo-4x4-norwegian-hiit/id6791945508 (this page in markdown: same URL + `.md`)
- Developer: [KRZYSZTOF ANDRZEJ OTRZASEK](https://appshunter.io/developer/6775732534)
- Category: Health & Fitness, Sports
- Price: Free
- Age rating: 4+
- Requires: iOS 17.0 · 3 MB
- Languages: American English, German (Germany), Polish, Mexican Spanish
- Released: 2026-08-09
- Data updated: 2026-09-07
- User reviews in markdown: https://appshunter.io/ios/app/crescendo-4x4-norwegian-hiit/id6791945508/reviews.md

## What is Crescendo 4x4?

The Norwegian 4×4 protocol builds VO₂max like almost nothing else — four 4-minute pushes at 85–95% of max heart rate. The problem? Starting there feels like hitting a wall.

Crescendo removes the wall. You start with intervals as short as 30 seconds and climb a structured on-ramp, level by level, until the full 4×4 is yours. Progress is earned, never rushed — the app can even gently hold a level-up if your recovery data suggests you need it.

GUIDED SESSIONS
• Voice cues for every phase — works with the screen locked, music keeps playing
• Warm-up, four work/recovery cycles, cool-down: fully guided
• Date-anchored timing that never drifts

PERSONAL BY DESIGN
• Heart-rate zones from your real max HR — from Apple Health or set manually
• A conservative level-up gate that watches your resting HR and VO₂max trends
• Start where YOU are: from 30-second familiarization runs to the full protocol

APPLE WATCH + HEALTH
• Send any session to your Watch and run it from the native Workout app
• Watch-run sessions count toward your progress automatically
• Phone sessions save to Apple Health (your choice)

HONEST BY DEFAULT
• No account. No ads. No streak guilt.
• Your health data stays in Apple Health — we don't collect it.

High-intensity interval training is demanding. If you're unsure about your health, check with your doctor before starting.


## Version history (last 4 releases)

### 1.3 — 2026-09-03

Your session now lives on the Lock Screen.

Start a workout and Crescendo appears on the Lock Screen and in the Dynamic Island — current phase, interval, target zone, and a countdown that stays right whether the app is open or not. Pause in the app and it holds. Finish or stop, and it clears itself.

Also in this release:
• The main Today buttons no longer shrink to unreadable text at large accessibility sizes — they wrap instead.
• If an update moves you up a level, the app now says so instead of doing it quietly.
• Translation fixes.

### 1.2 — 2026-08-26

Crescendo now speaks Polish, German and Spanish — every screen, the Health permission prompts, and the guided voice cues. English stays the default, and your iPhone's language setting decides.

Plus small refinements under the hood.

### 1.1 — 2026-08-20

- A gentle starting-level suggestion. If Apple Health has a VO₂max reading, the level picker now hints at which rung could suit you, compared against published age and sex norms. It never picks for you — dismiss it and your own choice stands.
- Go back during onboarding. Change an answer without starting over.
- Edit your age in Settings, and erase the health data Crescendo has stored, any time.
- The Level Ladder now opens as a sheet, so swiping between screens no longer fights it.
- Clearer about Health: onboarding now names every kind of data Crescendo reads.
- Accessibility: Dynamic Type across the main buttons and headings, WCAG-compliant contrast on the active workout screen in dark mode, and Reduce Motion honoured.

### 1.0 — 2026-08-10

No release notes.

## More apps by KRZYSZTOF ANDRZEJ OTRZASEK

- [KanaLearn: Learn Japanese Kana](https://appshunter.io/ios/app/kanalearn-learn-japanese-kana/id6775732532)

All apps by KRZYSZTOF ANDRZEJ OTRZASEK: https://appshunter.io/developer/6775732534

## Related topics

[crescendo 2](https://appshunter.io/ios/topics/crescendo-2)

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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 2026-09-07.*