How does Xert analyse two back to back Activities differently vs one continous one?
I just did a 2hr workout and then timing lined up to do a Tour De Zwift ride (which maybe wasn’t the smartest choice - extra 40m - earning my stripes as a Surplus Seeker).
Other than total XSS for a day, would I get different ‘difficulty levels’ or any other metrics if it has been recorded as a 2hr40min Activity? I wasn’t doing real peak power efforts so I don’t think MPA resetting is relevant.
This also brings to mind the (hopefully) infrequent scenario when Head units crash mid ride and you end up with two files. I know it is possible to stitch together Fit files with Web tools.
Xert assigns all XSS at the start time of every recorded activity, so you’d see two separate bars on the XPMC and some jumps in the TL/RL (and subsequently, Form) lines. Not a huge deal. I just did two separate activities today and it just looks like this:
(rather a continuation of 1…) Because Xert adjusts signature parameters based on decay setting & training load, the second/third activity might have a slightly different signature, based on the accumulated XSS (Low, High, & Peak) from the previous activity. For example, my signature for the second ride today had a TP that was 2W higher. Overall, the changes tend to be small (2W increase in TP is less than 1% difference in TP for me, smaller than the error margin on my power meter). The extreme case might be a first activity that is insanely long (300+ XSS), in which case the jump in signature parameters might actually be more meaningful. As I mentioned, likely a bit of an edge case.
Difficulty score is an EWMA of XSSR with a 30 min time constant. Starting a new ride “resets” the difficulty, whereas a singular ride would simply continue the difficulty. This really isn’t a big deal, since Difficulty Score doesn’t affect any of your metrics/training - it’s simply a mathematically determined estimation of the high-intensity difficulty of a ride/activity.
We’ve done a lot of testing with EBC over several months - crashes were more common months ago when we were early in development, but should be rare by now. We’ve also emphasized ensuring that activities aren’t lost, even in the event of a crash. Simply closing and restarting the app should allow you to continue the ride (at least on EBC).
