Seems like for my most recent activities the kJ above FTP is not being reflected correctly, considering the time spent in those zones, most recent example, Zwift race 72 minutes long, 1200 kJ total work, 10 minutes spent in Z5, 8 minutes spent in Z6, however Work above FTP is supposedly only 97 kJ.
Doing the manual math my Z5 power starts at 318W which is 19 kJ / min → 19 * 8 = 152 kJ for the duration Z6 starts at 360W which is 21 kJ / min → 21 * 10 = 210 kJ → 210 + 152 = 362 kJ which should be roughly the correct value and would be inline with what similar activities have shown in the past for a similar power duration above FTP.
For your calculation, you need to deduct the kJ / min at FTP, so using your example, and assuming that your FTP is 318W (L5) / 1.05 = 302W, or 360 / 1.2 = 300W. To get to 97kJ, you would have been working in the upper half of each zone. Here’s how I calculate it.
Lowest Watts in each level Level 5 power
Power above FTP = (318 - 302) = 16W
Duration above FTP = 10 minutes
Watt Hours = 16W * (10/60) = 2.667 * 3.6 = 9.6kJ
For those of us that still like to use the total kjs whilst performing above FTP (how it was previously calculated), is there anywhere that we can still view that?
Thanks!
Unfortunately not. I did consider keeping two fields but decided that would be confusing. It will likely be possible to implement that when I get custom calculated activity fields working.