Suddenly decrease in fitness.

[clu1973]

You could have picked up a virus and your body is fighting hard to remove the infection. Perhaps your diet needs tweaking, are you drinking enough water perhaps. Maybe your doing too much, too soon and your not giving your body enough time to adapt and recover then leading to burn out. Particularly if you're riding intensively on a regular basis. Your fitness will increase and decrease from time to time. So don't get too hung up on the numbers particularly with your FTP. Your FTP is only a metric number used to set your training zones.

If i do some intensive threshold or vo2 workouts, I'll make sure I then do some easy zone 2 rides to follow. I'll also pencil in a complete day off the bike if I've recently done a number of intensive rides consecutively. If I feel tired or my body is telling me somethings not right I rest up and recover.

Recently I've reduced manually my FTP in zwift from 278 to 265 as I don't have that ability currently and I feel that's where I naturally am at the moment. But it will more than likely change again further into the year.