FTP stands for Functional Threshold Power. It's the maximum power (measured in watts) you can sustain for roughly an hour on the bike. It's the most widely used benchmark to describe cycling fitness and intensity.
Why does REN ask for it?
If you cycle alongside your running training, those rides affect your body. A two-hour endurance ride puts a different load on your legs and energy systems than a short recovery spin. To account for that, REN needs to understand how hard your cycling sessions actually were.
That's where FTP comes in. When you set your FTP, REN can use the power data from your cycling activities to calculate training load more accurately. This helps REN adjust your running plan to reflect the total stress on your body — not just your runs.
What happens if I don't set it?
Without an FTP, REN has no reliable way to interpret your power data and the intensity of your rides. It may underestimate or overestimate how much a cycling session took out of you, which can lead to a running plan that's either too ambitious or too conservative.
How do I find my FTP?
Most cycling computers and apps (like JOIN, Garmin, Wahoo, or Zwift) estimate your FTP automatically. You can also do a dedicated FTP test — typically a 20-minute all-out effort where the average power is multiplied by 0.95. If you already use a cycling training app, chances are your FTP is listed in your profile or settings.
Once you have it, simply enter it in REN under your settings and you're good to go.