Supplementing base phase with HIIT

Hi all,

New to Trainer road (but not new to interval training), and finished week 1 of the SSB LV1 block. When looking through the planned workouts, it makes me a little nervous that i’ll almost never get to/above FTP. Would it be a bad idea to add on the occasional high-intensity workout, perhaps 1 per week?

I understand that this is not the purpose of the base phase, but I don’t like the idea of deconditioning the MAP/Vo2 max/sprinting that I have built up.

A little about me, if relevant:

I spend 5-6 hours per week on the bike. Mostly moderate intensity outdoor mountain biking. About 2-4 high intensity workouts per month on a trainer. Baseline FTP just riding outside is about 3 W/kg, and with the odd HIIT workouts over the past year, FTP has increased to 4W/kg. The addition of HIIT has made my outdoor rides more enjoyable, as I never get cross-eyed exhausted unless I choose to, and recover quickly from the hard efforts. I don’t want to lose that!


The simple answer would be yes. It defeats the purpose of the base phase to do this and will compromise the long term training cycle by introducing more acute fatigue and you will likely plateau faster as you won’t be building as solid a foundation.

Whether you care that much about this is another matter, if you are training for races to maximise your result this wouldn’t be the way to do that. Adding more volume in the form of endurance or maybe tempo would be good. But, if the goal is to be generally fit and enjoy cycling then it really doesn’t matter that much.

The one thing I would say is that your sprint, 1 minute and 5 minute power are the things that will leave you most quickly, but building them back up will not take long. I have seen a 20% improvement in my 1 minute power in 4 weeks training when I worked on it after not training it for a while, so I wouldn’t worry about losing this ability as it will always be there, and will likely be improved with a better base.

FTP and aerobic abilities on the other hand take a long time to improve, and require long term concentrated training on this area specifically to make substantial improvements, hence why base phases are typically much longer than build phases and why cyclists that train consistently generally see improvements from year to year.

This is probably going to be a “it depends” answer I’m afraid.

Do you have any specific races/events/dates for reaching maximum performance?

If the answer is no then I think doing base “as prescribed” would be your best choice. You may well lose some top end, but you cant maintain top end 365 days a year anyway, and laying a good base (without overtraining by adding in additional threshold work) will give you a good situation for building even better threshold and VO2 max in the future.

If the answer is yes, then when are these? If you have races coming up in the next few months which are heavily reliant on ftp/vo2 max then I might suggest you do some sort of maintenance work that might be something like you describe, maybe 1 intensity workout a week and 2 endurance/base?

If the answer is yes, but not until 3,4,5+ months away then refer back to the “if the answer is no” suggestions.

Just my opinion :slight_smile:

Cool, appreciate the insights.

To answer questions, no, I do not have any specific events I’m planning for, just going for overall fitness. For that goal, sounds like it probably doesn’t matter a whole lot, but I’ll get the most out of the training by sticking to the prescribed workout types.

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FWIW, if you don’t have specific goals and aren’t putting in that much volume, the odd higher intensity session won’t ruin your base period. If you enjoy them and they keep you motivated, one VO2 session every week is probably fine. The most important part of training is consistency and doing what you enjoy tends to help greatly with that.

I’d go as far as to wager that for most amateur cyclists the standard long term, annual periodization is probably of much less physiological benefit than it’s made out to be.