I think (from looking at power files) it’s the additional torque required to grind low RPMs in the aero position; I don’t know exactly why it works from a physio standpoint.
Why would changing inertial loads change one’s ability to generate power?
Yes, but let me first state this is what I believe works for ME (and a bunch of really good TTers I know), without any controlled medical studies to confirm that.
One of the staple workouts I do is called HOP, or hour of power. You build time and power, from 3x10 to 60 min, done at 70 to ~85% FTP, and 60-70rpm. They’re not that bad until you get to 2x30 min at higher power. The last 15 min of 1x60 is brutal. The muscle activation though hips/glutes is very different than any other workout and adapting to an aggressive aero position. Aside from that, it’s a great way to work on position discipline and concentration.
There was a long post on this that my inadequate search capabilities wouldn’t pull up. I think Joe Santos, Tom A and some others were all in it talking about position in case you want to look for it.
just wanted to clarify something here. there is an “hour of power” (or “HoP”) workout that is described in allen & coggan’s “training and racing with a power meter” book, and was created by bill black. you can also find it in an old usa cycling newsletter (page 6 here: http://www.usacycling.org/forms/newsletter/newsletter0413.pdf).
sounds like you have a different “hour of power” (if i understand what you are typing), which is fine – but since bill’s HoP is pretty well accepted in power-training circles i wanted to point out the distinction.
disclaimer: bill’s my coach. this is a fantastic workout on the trainer; time really flies!