About this app
Use Zephyrus to test your cardio fitness (VO₂ max) on a treadmill, and track your improvement. You can also use Zephyrus to do HIIT workouts. The app comes with a selection of workouts, and lets you create your own workouts. Zephyrus tells you when the target zone changes. To get your heart rate in the app, you can use Apple Watch or heart rate monitors with Bluetooth. Garmin watches with Virtual Run are supported. Cardio fitness is measured with a modified Bruce protocol test you can perform on most treadmills. The test consists of stages with increasing intensity and ends when you reach 85% of maximum heart rate. You can do HIIT workouts on Apple Watch, so you don't have to bring your phone. Your past workouts are saved to your workout history, where you can see the heart rate graph and calories burned. Your data is stored in iCloud, which makes it accessible across your Apple devices. Always consult with a healthcare provider before starting any new exercise program. Exercise can carry risks, especially for people who have certain medical conditions or who have not been physically active in a long time. It's important to understand that using this app does not replace a doctor's advice or treatment. If you would like to report an issue or request a feature for the app, feel free to contact the App Support email. Terms of use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
Latest release
What’s New
Improvements and bug fixes
Audience growth
Ratings growth
Baseline captured. Growth appears after the crawler observes a changed rating count.
Momentum comes from crawler snapshots for the tracked storefront. “Viral growth signal” means unusually fast recent rating gains; it is an indicator, not download data.
Price tracking
Price intelligence
First snapshot captured. The trend line starts after the next crawler price observation.
- First observed Aug 19, 2026 · 7:41 PM Free
Screenshots
