OK, so I think I dismissed polarised training a little too quickly without fully researching this type of training. In fact, I think I might actually ditch my current sweet spot mid volume plan and give it a go. Like @DaveWhelan said, the only way to find out if it works is to try it for yourself.
Why the change of heart? I was originally put off as the 90% easy to 10% very hard ratio just seemed too skewed to illicit any adaptations for time crunched cyclists like myself. However, when you enter the numbers into a plan you soon realise that 10% equates to quite a lot of time at a very high intensity. So for a 7.5 hour week that would 45 minutes, which I think is quite a lot of VO2+ work.
I quickly planned out a year of training using the standard 3 weeks on 1 week off where on the 4th week I simply reduced the amount of time by 40% with the plan of still incorporating some high intensity work (the ramp test near the end of the week). By gradually increasing the weekly training time, this would take me up to 10-11 hour training weeks by the time I would normally be completing a Build phase. This would be a lot for me, but I think it may be manageable. An 11 hour week would require about 66 mins of time at the high end.
Seiler et al. recommend making 80% or training sessions easy and 20% hard. However, this doesn’t really fit in with my plan. At 7.5 hours a week, I think 1 session with 45mins of very hard intervals would be too much, so I was thinking of splitting the time between two sessions with the ratio 65:35. The longer session on the Tuesday and the shorter on the Friday. This would equal 30 minutes for session 1 and 15 minutes for session 2. As the season progresses I would change the ratio as the total weekly time goes up.
With regards to intensity, Seiler recommends that people do a lactate threshold test to work out LT1 & LT2, however for me and what I am training for, this would be overkill and not repeatable. I’ll just be using the standard Coggans power zones instead.
Despite some people lumping sweetspot into Seiler’s zone 1, I think this would be too intense for me. This means that I’m going to try and keep my easy rides within zone 1 &2 with the inevitable drift into Z3 while riding outside. The hard intervals are going to be 105% ftp and above.
I’m have difficulty choosing the best intervals for each phase of the season. My goal is to be competitive in several crits from mid May to July. So, do I train more on longer intervals in base and then as I get closer to May start reversing this so that I do shorter and more harder intervals as I approach the crit races? Or should I just mix long and short as I go through the base period and then change this to more shorter harder intervals as I get closer to the race season?