This plan takes you in three 4-week blocks from a bit shorter 4 HIT sessions in the first block week to absolutely hard 5 HIT sessions in the last block. The intention is to progressively develop the harder sessions and week durations so to build a good form. After completing this 12-week-plan you definitely worked fantastically on your VO2max and can then focus on either the next focus and/or stabilize your newly gained VO2 by raising your weekly (base) volume.
It is useful to having had a phase of a few trainings with some intensity to get used to it beforehand.
Road Cycling, Long distance cycling, Gravel Racing, Unsupported Racing, Triathlon