When to do anaerobic intervals?

When are you doing anaerobic intervals and how often and how much it is needed for adaptation and also how long it needs to see adaptation?

So if you do aerobic base (endurance + sweet spot) and then build (FTP over unders + vo2 max), and then specificity… When to put anaerobic block or anaerobic intervals (30s-90s)?

Last 6 to 8 weeks before you really need them.

If you find your power in that zone drops off really quickly, consider doing a short workout of them every two weeks or so during build, or even base. Or just do a Zwift race.


I think this varies drastically from person to person. For me, 4 weeks out is a lot. Anaerobic intervals and sprints are incredibly hard on your body out of proportion to IF and kJs burned, i.e. 1000 kJ in a sweet spot workout is much “easier” on your body (and requires less recovery) than 1000 kJ of an anaerobic workout. You can burn yourself out very very quickly if you do too much.


How about if you don’t really need them for you A-goal event?
My main goal is an 8hr Alpine Gran Fondo. Does it make any sense to fit them in if I know I won’t go over Treshold during the event?

For now I have them planned for a short period at the end of the base period. After that a VO2max block and finally a treshold-block before a taper period.

If you listen to the podcast, you know this comes up all the time - if you are racing a bike or doing something like a group ride or grand fondo, you are very likely pushing occasionally into anaerobic zones. Those brief instances can totally thrash you if you don’t have the appropriate bit of training. Maybe do less if it is not an anaerobic event, but it can be a deal-breaker IME. It also doesn’t take months to build. With a few sessions (3-4), you can make real progress. You might not be the most anaerobic person in that race with only a few sessions, but you will certainly be much more pointy.

On the other hand, I did a full-distance ironman and my NP and average power were identical with zero pushes even into sweet spot, so there are instances where you literally don’t need any above-threshold capacity. But, they are few and far between.

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really depends on the athlete. If you have enough anaerobic capacity needed for your events, then just wait until they get close and brush up on it. If not, and you really need to alter the physiology, you might be better off scattering them throughout the training over a longer period of time to truly adapt in how you create energy. This can take some time, but is super effective for those that need it!


Totally agree with Brendan here.

It’s absolutely rider dependent.

Are you anaerobically gifted? If so, you can usually leave it till quite late before your event. 3 to 6 weeks, depending on the individual and the event requirements.

Are you aerobically gifted, but need anaerobic power for your events? Then sprinkle it in a bit earlier. Maybe 8 weeks out. Again this is not a one size fits all approach.

Not a racer. Likely best to just sprinkle it in when you feel it’s appropriate.

Test a build, see how it goes. Adjust it next time if you find it too hard too early, or the opposite.

It’s very high demand training. You need to be fresh and well fueled. Additionally, I feel it’s very valuable to have periods of the year where you barely get even near to touching this kind of intensity. Essentially, the rest and refresh stage. Be that, a season break or short intensity breaks during the year.

Unleash the beast :grinning:

Just race CX once a week and youll get a lifetime’s supply of anaerobic workouts!

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So when you guys say 4-6-8 weeks before race how this block will looks like? Once a week anarobic + one vo2 or FTP hard day and rest is endurance until taper or you suggest x weeks before to do anaerobic block for 2-3 weeks?