FTP estimation

I started to use this site a couple of weeks ago and imported all my activities from Strava, so far I’m happy with it.

I do a lot of non cycling activities during the winter and spring and I have no idea how I can put a reasonable XSS for the activities and a consequence of that is that I see a increase of +50w in just a couple weeks which might be inspiring but useless if I try to use FTP for intensity during that time, would probably kill my fitness.
Then during the summer when I only do “submaximal” efforts the FTP is dropping slowly but each time I do a max effort the FTP jumps up.

This week I had a breakthrough on Tuesday groupride, a hard but not max effort, my group ride today had me near a breakthrough in the middle of it but at that point I was no where near exhaustion and could have produced the same amount of watts for at least 20 seconds more if the ascent was longer.

The Tuesday ride gave me 14w increase which sound like a lot but I don’t think my ride today will give me any increase in FTP even though I know now when I look at the numbers I could ha ve gotten a breakthrough on this ride as well.

The last month I lost 17w and earlier this week I gained 15w, my guess is that my FTP stayed pretty much the same during this time.

The questions.

  1. why does my FTP drop when I do submaximal efforts? and why does it change as much as it does for me?
  2. How can I estimate reasonable XSS on activities that I don’t have powerdata for, is there some general guidelines? I can buy a powermeter form my MTB but it harder for the other activities like floorball and tennis that I only have heartrate data for.

Hi Patrik,

Good questions…Xert is the first platform to show that your TP changes on a daily basis, rather than being some static number for 4-6 weeks (or longer) at a time. Further, your TP is sensitive to breakthroughs, as you’ve discovered, but also to training load (i.e. TP will increase if you start riding more than you have been, even without a breakthrough effort). I suspect your 50W increase may be caused by overestimating XSS on manual activities.

In response to your specific questions:

  1. FTP slowly decays slowly when no maximal efforts are detected in order to make it easier for the system to identify your next breakthrough. If you’re in a period of time with lots of sub-threshold work and not a lot of maximal efforts, we recommend switching your decay method to “No Decay”. You can find out more about that here: http://baronbiosys.com/xerts-magic-setting/
  2. In general, we recommend not to add non-cycling activities to your progression. The way Xert is set up now is to display your cycling fitness. Although things like floorball and tennis are great sport s for cross training, it’s difficult to determine how your cycling fitness signature changes in response to playing 1 hour of tennis/floorball vs. 1 hour of cycling. We recommend using the freshness feedback to accommodate how you feel before performing a workout. We have a guide on adding non-power activities here: http://baronbiosys.com/faq-items/how-do-i-add-activities-where-i-didnt-have-a-power-meter/