Originally Posted by
furiousferret
Bear in mind, all training software tracks CTL a little bit differently. As an experiment, I'm using WKO4, Golden Cheetah, Cycling Analytics, and Stravastix none are the same in terms of CTL with a difference up to 15. GC and Strava (baseline) are on the low end, while WKO is on the high end. I don't think that matters in terms of training, but one persons 90 CTL is another person's 75.
GC's version of Normalized Power uses a slightly different calculation than Training Peaks/WKO, so this is going to affect TSS of individual workouts as well as overall CTL/ATL. Generally those numbers will all be slightly higher in Training Peaks/WKO than in GC. For rides with more varied/intense efforts, the difference will be greater than in rides that are more steady state. I prefer the higher WKO numbers, because I think they better reflect the training stress of high-intensity efforts. I still feel the whole TSS/PMC concept is too heavily weighted to volume rather than intensity, but at least the balance is a little better with WKO's numbers as opposed to GC.
I do think there's more to race fitness than just CTL, but I also think it's a useful metric. I got up into the 90's during last base and early build over the winter, on about 10hrs/week although some of my base weeks were more like 14. After being off the bike for 12 days during vacation in April, my CTL took a big hit. I got it back up to 70-72 range when I resumed training, but it pretty much plateaued due to more racing and less total training volume (despite doing plenty of intensity). I feel my fitness is still decent at 70 but definitely not as good as it was before the vacation break, and it's not just endurance/FTP type efforts that are down a bit, VO2Max power is also not quite as good despite being focused on that in training the last month or so.