The following is a transcript of an email from the Wattkg Research Review newsletter:
I kind of left you hanging at the end of our last email.
Remember we discussed how you can benefit from including high-intensity intervals in your base training?
I promised I would address the question of how often and how long.
The answer is a bit of a let-down. But PLEASE stick with me, because the answer is nevertheless important.
The interval sessions in your base training should be…
…as long and hard as they NEED to be to push your capacity upwards.
You see, the “correct” answer most likely DEPENDS on your current fitness level. And the whole idea is to induce a training load that is big enough to drive your fitness level upwards.
When you first begin training for a new season, your fitness level is usually low. Therefore, a combination of easy rides and short threshold intervals might be enough to induce sufficient training stimuli (because at this stage, you don’t need a big load to improve).
I suspect this is why we so often hear we “should be doing threshold intervals only” during base training. It’s a low risk strategy that works for a while.
However, you might soon achieve additional gains by throwing some intervals with even higher intensity into the mix (because of the added intensity -> additional load = greater adaptation).
I raised this question because there is an important lesson to be learned here. If you never test your capacity, you don’t really know whether your training is working as it should (or not).
1) Test your capacity every 6-10 weeks
Any test will do. Timed maximal effort up a hill. FTP-test. Comparing average power output during a standardised interval session. Or VO2 max and lactate profile tests if you want to get fancy.
2) Have you improved over the last 2 months?
If YES: continue as you are (and maybe add some slight increases in load in time).
If NO: you should probably make changes. Figure out what to try next, and give it a go. The re-test in another 6-8 weeks.
The take-away-point today is that during base and build training, proper training should yield fairly regular performance gains. And a very simple and powerful way of tracking the effect of your training is by running basic and regular performance tests.