Originally Posted by jsirabella .
...I thought that maybe the drop/rest/rebuild in CTL from 2/20 to CTL of 99 on 4/16 could be part of the reason of the new high. ...
It may very well be part of why you actually saw the new high. I misinterpreted your earlier post and thought you'd seen higher power numbers, readjusted your FTP, and then seen a CTL drop in that sequence. It seems that you had a training interruption for travel, your CTL dropped and then you punched out some higher power numbers and subsequently adjusted your FTP. That's not surprising as a bit of freshness can go a long way.
But the question is whether your body suddenly adapted and your FTP actually rose or you just got some extra freshness and finally saw the results of your training that weren't obvious till you got some additional recovery. I'm guessing the latter. It get's back to what FTP is, and what it isn't. It is your best sustainable power for roughly an hour set on an ideal day with adequate recovery, nutrition, hydration, motivation, pacing, etc. What it's not is your day in, day out on demand power for an hour that you'd expect to see whenever you want. From that standpoint FTP represents your capabilities and not necessarily what you see in your power files on a daily basis and although you saw it after some extra freshness, the real adaptations that delivered that higher FTP were happening even when you were carrying too much training fatigue to see it.
Regardless, your numbers moved up and it doesn't sound like the CTL drop was a result of the FTP increase, more of a coincidence.
... Cause it would seem to me that if I just keep with SST/L4 work indefinitely that CTL will just grow and grow and grow. Even though I have to admit from a week off I can see a 10 point drop! So it can fall back pretty fast.
CTL will only continue to grow long term if your training load in weekly TSS also grows long term and in absolute power terms that gets harder as your FTP rises. So new FTPs are a bit of a double edged sword, we all want to see them go up but every time we reset our FTP we know that we now have to work at higher absolute power levels or for more time to continue to grow our CTL. In relative terms it shouldn't matter as we shouldn't bump up our FTP for PMC purposes unless we've got the additional fitness to back it up in which case we're still working about as hard in a relative or RPE sense. Or as Lemond said 'It doesn't get an easier, you just get faster...'
CTL drops roughly 2.4% between the current value and the TSS of each day. So if you take a total rest day your CTL will drop ~2.4% of your current CTL. If you do a workout that yields a TSS of twice your current CTL your CTL will rise by ~2.4%. Do a workout with three times the value of your current CTL and your CTL will rise ~ 4.8% of its current value, etc. So basically it takes a lot to make up for a complete rest day and is one reason to include some active recovery days that yield low TSS, help you to bounce back quickly from harder days but still prop up your CTL a little. For instance do a steady low to mid intensity ride that yields a TSS of half your current CTL and your CTL only drops ~1.2% which is a lot easier to regain on subsequent harder training days. We all need rest but not every rest day needs to be completely off the bike.
... I thought maybe part of the lesson is when to know NOT to train....
That's definitely part of what the PMC and tracking CTL can show you but IME it's tied closer to things like CTL ramp rate and sustained negative TSB than it is to adjusting your FTP setting.
-Dave