This year, I had a consultation session with a coach in January, planning through two target stage races in Feb (VoS) and early April (Tour de Murrieta). He had me do base only leading up to VoS (w some light SST on the TT bike) and then go straight to VO2 intervals.... no z4 or threshold riding in between, per the classical progression. During March, I was doing 3x VO2 workouts per week with around 20' in zone per session, and z2 long on the weekends. Very polarized. He said or someone like myself I needed to block periodize to move the needle, and he identiied VO2 as a growth area.
The training month was tough, but man I felt like I was flying afterward! Three wins in the 35+ this year in SCNCA. including the criterium at TdM, which I won from a break I started.
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"Your beauty is an aeroplane;
so high, my heart cannot bear the strain." -A.C. Jobim, Triste