If you are regressing in fitness, it's
probable that even though you are following a polarized model, that your overall workload is lower. How many kJ were you doing per week in the under a threshold/SST model, vs. the polarized model?
Actually in each of the three 8 week blocks where I performed polarized trials, I had to significantly increase my kj of total work in order to match
the weekly TSS I'd been generating just with daily sweet spot training. One of the interesting things I noticed during my trial was that on the second easy day in a row I'd start pissing away blood volume. Normally I never need to get up in the middle of the night to urinate. During polarized training every second easy day/night I'd be pissing like a race horse. I do find Seiler's research/arguments compelling and have been surprised and disappointed to not see positive results from polarization.
I've also had very good results doing 2x20's at 93-95% of FTP. I found I was able to do them every other day and recovered sufficiently session to session. This winter I'm going to experiment with some polarization and introduce Seiler's "Magic" 4x8s. What I've noticed so far is that I'm not sufficiently recovered 2 days after 4x8s to do 2x20s at 95%. I guess i'll try my 2 day after at 90% and see how it goes.
There were some posts in the cycling physiology forum (https://groups.google.com/...m/cycling-physiology
) attempting to explain how or why those 4x8s are so good, but I just wonder if enough controls were put in place to truly differentiate 4x8s from 8x4s or 2x16s. Supposedly the HIIT sessions were "self paced". Does that perhaps mean folks didn't push themselves hard enough in 4x8s. Who knows. They also tried to explain it as hyper activation of PCG1-a.
We know that PCG1-a (a master gene regulator that switches on mitochondrial biogenesis and new capillary growth amongst other things) is switched on during exercise and the effect is amplified when you train
with low glycogen
That still doesn't explain the better results they reported from 4x8s over other durations.