Training block length

Does anyone have any insight, reasoning, or experience behind deciding between a 2 week on 1 week off approach vs a 3 week on 1 week off approach to your training blocks? I know some TR blocks are even 5 on 1 off. I’ve seen the 2/1 option in the TrainingPeaks ATP builder but haven’t tried it.

My reason for asking is that a few times this year at the end of my 3/1 blocks I’m getting sick by the end. Today is the last day of my current block, and I can literally feel it. I couldn’t hit my TSS, I have a sore throat, etc. These have been after multiple blocks back to back FYI. But I’m wondering if maybe for myself personally it would be better to do two harder weeks, then rest again? I’m worried obviously that without as much accumulated fatigue I won’t get as fit in the long run, but getting sick isn’t going to work either.

Also FYI I’m lucky to have a very simplified lifestyle compared to many people, I put a lot of care into my diet, sleep schedule, etc so I feel it’s not that, it’s the workload. Riding only indoors (like this current block) I’m usually in a 550-600-650 TSS type progression.

Anyway, any input or experience to block scheduling I’m interested to hear.

Maybe just too much training load for you.

I think the 3 on, 1 off approach is about building up sufficient training stress to produce results within a reasonable time frame. Maybe 2 on, 1 off could work, but much slower or with finished gains. Kind of like a course of antibiotics; you have to nail to for to 12-14 days consecutively or the antibodies don’t build up sufficiently in your system.

If you really are eating enough, sleeping enough and still getting sick at the end of every block like clockwork, less TSS could be a starting point for regulating that.

Trainingpeaks has the option of four week 3-1 or three week 2-1 blocks when planning your Annual Training Plan ATP.

I read somewhere, maybe TrainingPeaks, that a three week block is recommended for Veteran athletes or people with high stress or physical jobs. Guess that also applies to having general high life stress or poor recovery (diet, sleep etc)

I’ve been experimenting with a three week cycle…
16 day normal training / 5 day decompress regen period.
So every third week Monday-Friday is like a normal recovery week, but the weekend, with extra time availability is back to normal training building fitness.

If you’re consistently getting sick at the end of a 3 week block and it’s not down to anything you’re doing off the bike, then that would be a big red flag that you need to change something. Either a 2:1 ratio, less TSS, or same TSS spread over more time (e.g. a more polarised approach). If you haven’t already then maybe also worth getting a blood test and checking there aren’t any underlying issues that could be causing problems when you’re tired.