About a month ago, I had a relatively mild case of covid (vaxed and bivalent boosted). I took two weeks completely off the bike, then a few days of Zone 1, then two weeks of Zone 2. My Zone 2 rides felt normal/good. Today I tried to do 2 x 20min at my former threshold power. I could only complete about 13 minutes of each interval. At about the 12 minute mark my heart rate and muscle acid buildup was really spiking up, so I figured I would dial it back, recover and try again. The second interval went the same. I have read that it takes about a month of training to get the muscle fibers back to previous levels after a break. So the question is, do I retest/reduce my FTP for future intervals, or just do a couple of more weeks with shorter/partial intervals at my previous FTP with the hope that my body will relearn/reset to my previous FTP? Zone 2 power feels normal and Zone 2 heart rate looks fine.
Your initial return strategy was good. However due to the time off and illness, you shouldn’t expect to have the same threshold durability. I would recommend you follow the sage advice found in this thread. Won’t be long and you’ll be back to your old self.
This seems like a good approach - thank you!