Name: What's My FTP? - Xert
Rating: 3.6 (89 reviews)
Author: XertBreakthroughTraining

Discover, Improve, Perform with Xert Breakthrough Training - www.xertonline.com

Never do an FTP test again.

This convenient simple datafield determines your FTP *on-the-fly*, continually updating and increasing the value the harder you ride.   Using a sophisticated Xert™-based algorithm, the app uses patterns in power data coming from your power meter and looks at how you fatigue to provide an estimate of your FTP.  Use it during regular riding or use it during FTP tests, if you prefer.  You don't have to worry about pacing or interruptions.  Just ride as hard as you can, right to your limit, and you'll then have your FTP.

Directions: 
1. Install onto your Garmin device using the Garmin Connect iPhone/Android app.  
2. Start your device and add the datafield to your Activity Profile. Full screen (i.e. 1 datafield screen) works best.
3. Start your recording and switch to the What's My FTP? datafield view.
4. Perform some sprints. Do several all out 3-5 second efforts producing as much power as you can.  Do these to help calibrate the algorithm.
5. Ride to make the value increase.  Once the circle around your FTP value reaches back to 12 o'clock, turning purple, your FTP estimate will increase. Increase it with hard efforts, less hard efforts, non-stop efforts or efforts with breaks in between.  Doesn't matter with this datafield.  It'll figure out your FTP based on your efforts.
6. Once the value cannot be increased anymore, it will show you your FTP.  

If you require an Xert Code to enable the data field, subscribe to Xert at https://www.xertonline.com and review the page https://www.xertonline.com/garmin-connect/iq.  Enter the Xert Code from that page into the What's My FTP? datafield's settings using Garmin Connect Mobile.