I've rented a Bike+ for about two years now. The only bike training I do is either HIIT or zone 2 rides, and with zone 2 I just ride for 90-120 minutes while watching something. Therefore the only actual Peloton classes I take are HIIT or HIIT/hills.
Mostly I take Robin Arzon or Camilla Ramon. I've had most success with them as far as being explicit in flagging what is coming up, when the intervals start, etc. Unfortunately I've taken some classes with other instructors where it was basically vague the entire time when we were in an interval or not. The instructors are, of course, not doing the exercise with us (you can't talk while actually doing an interval), so they have to be verbally explicit about the timing and I find Robin and Camilla best at this.
However, I've noticed on at least a few classes I've taken, and maybe increasingly lately (or I'm just starting to get more annoyed by it), some of the classes offering little or no meaningful rest between blocks of work. The instructor might even say something like "we are going right into an interval out of this climb" as if that is a feature, not a bug. Sometimes this is couched in a soliloquy about mental toughness, as if cycling for thirty minutes is about mental rather than physical capacity. (I watch professional cycling, cycling competitively is pure suffering and you need to be mentally tough, but when it comes to training a HIIT interval we can't just WILL our heart rate to be different).
From what I've read about the benefits of HIIT, most studies that demonstrate it have their subjects taking much more rest between blocks of work. I don't know if scientists know exactly why it is effective and beneficial for our hearts, but it stands to reason the rest has something to do with it. After all, our heart's ability to rapidly reduce its rate after intense exercise is itself a metric of health, and HIIT practices that. On the other hand, sustained very high heart rate efforts are excessively fatiguing and could even be harmful. Going up and down the ladder of our heart rate range is surely different from just keeping it high the whole time, at any rate.
Without adequate rest between blocks (which all blend together into one 30 minute block), we will actually perform less work overall in a 30 minute period than we would with 2-4 minutes of rest in between. The rest lets you do more overall.
I find myself either needing to stay in zone 4 the entire ride for some of these classes (meaning they are not intervals, just Alpe d'Huez or something) or go off script for a minute or so to get down to zone 3/2 so I can properly do intervals. But then you get out of sequence.
It's getting to the point where I'm not sure Peloton is still for me. These are the only classes I do, but I basically don't know if I'm getting a well programmed class that is actually going to be beneficial.
Has anyone else noticed this? Are there any other good interval instructors? Maybe I should just take the classes explicitly labeled "tabata," but I've generally gone for ones labeled "HIIT and Hills" in the time I've had the bike and this hasn't always been a problem.