A sophisticated app aimed at group testing and advanced individual testing. Please take some time to examine it (see https://youtu.be/yFrDFCJUfyE). Do a few "dry" runs before going live with it.

Yo-Yo Intermittent Pro is an enhanced version of the free Yo-Yo Intermittent Test app available at https://play.google.com/store/apps/details?id=rudy.android.yoyo.

Both help conduct the Yo-Yo Intermittent test (Recovery Level 1, 2 and Endurance Level 1, 2) as defined by Jens Bangsbo of Copenhagen University

In addition to what the free version has to offer, Pro provides the following:
Multiple Users, large group. See https://goo.gl/D13dmC
--- Maintain lists of names - save/reload them
--- Edit, delete, save, reload results
--- Graphical analyses -- various
--- Switch between "Enclosure" and "Name" mode
--- Import names ...sdCard, Cloud [Gdrive]

- Estimates vo2Max (Recovery Level 1, minimum 1000m)
- View progress ... multiple graph options
- Training options - skip levels, loop a level
- Sort Results. Name, Distance or Date
- Export results, via email
--- Paste-Special directly to GoogleSheet
--- Or load into other spreadsheets

Work out, stay fit, rock on!

[Reference: Fitness Training in Football, a scientific approach - by Jens Bangsbo (December 1994)]

Caution: Audio. There are tens of thousands of Android phone variants. Invariably, the odd one has issues. Validate audio (incl. Bluetooth) using the free version.

Step 1. Download Yo-Yo Intermittent Pro Mod (Paid for free Free purchase) APK file on HappyMod.com.
Step 2. Once it's downloaded, open Downloads, tap on the APK file, and tap Yes when prompted.
Step 3.Yo-Yo Intermittent Pro Mod (Paid for free Free purchase) APK will begin installing on your device. Simple.

Step 1. Download HappyMod APK file on HappyMod.com.
Step 2. Once it's downloaded, open Downloads, tap on the APK file, and tap Yes when prompted.
Step 3.Search Yo-Yo Intermittent Pro Mod, click Download.
Step 4: You can download 100% working mods on HappyMod with one click.