XSS in a Nordic Cross Country session

I am new in Xert. I like this Software, but i am not sure, if it is suitable for me. Sorry for my bad english. I hope, that i can explain the situation correctly. So we live in Germany and in Winter, we do a lot of nordic cross country (skating), because of weather conditions its outside difficult to cycle, but the main sport is cycling. So i have while skiing only heartrate, speed and distance and altitude. Yesterday i got for 10km and a average heartrate of 174 bpm only a xss score 9. TP shows me a 112 Hrtss and Strava which has no TSS, but something different shows me 116.
I think xss is to low. What can i do or how to deal with it to use in future Xert as an appropriate tool.

Thank you very much



What device were you using to record the workout?

I am curious to get input on this as well. Using my Garmin (with HR strap) I got an XSS of 159 on my last nordic session (2hr50min, AvgHR=133, 32.5K), but when I use my Apple Watch (with optical HR sensor) I get a much lower XSS.

I use Polar Vantage V and i send the data to TP and Strava.

It might not be a 100% reply. But after using Xert for both cycling and running (with Stryd/power), I have a look on my XC classic sessions average HR and usually calculate around 1-1,5 points of XSS per minute of exercise. If it felt really easy maybe around 0,7-1 XSS/minute.

I just stumbled upon this, and will add my simple method. I too do XC skiing in the winter. At this time of the year I’m happy with an approximate XSS so Xert doesn’t start telling me I’m slacking when in fact I can barely walk :sweat_smile:

I took a look at some indoor Zone 2 rides, where my HR is roughly at 130bpm, and they will generate about 55-60XSS per hour. Then I wear an HR monitor when doing XC skiing, and apply the following simple algorithm:

  • Count moving time only, in fractional hours (so 1.5hrs for 1h30m, 1.75 for 1h45m…). If I stop to get my breath back, this time doesn’t count.
  • Multiply this time by 60 XSS per hour, which is adjusted as per average HR in the session as follows:
  • Take my average HR for the session. For each bpm that it’s over 130 I add 1 to the XSS per hour. For each bpm under 130, I substract 1 XSS

So for example, if I do 1h30m of XC skiing at an average of 125bpm, then the XSS would be computed as follows:

1.5h * (60 + (125bpm - 130bpm)) = 83 XSS

I could go more analytical, but this approximation makes me happy. I just wish I didn’t have to do it manually every time, it gets tedious

1 Like

I also raised this question a few days ago:

You will probably not get a 1-to-1 benefit of the XC skiing to cycling for the same heart rate because you are using additional muscle groups. Adding the XSS manually will inform Xert that you are tired, but it will also increase your fitness signature more than what is realistic?