Last weekend I read about Amber's 2 hour spin above 100 rpm. http://seesally.blogspot.com/2008/03/successful-saturday-spin.html
That totally impressed me, so tonight I decided to try a mini version of that, within the IGP™ calling for a 60-70 minute spin. I knew I'd burn out pretty quick if I tried to maintain 100 rpm, but figured I could maintain 85-90 for a while. The next challenge was to stay upper zone 2, which for me tops out at 120 bpm.
10 min warmup gradually finding a gear to get me to target rpm and heart rate.
30 minutes, almost entirly at target rpm (more about heart rate in a minute.) My image was a long straight stretch into a headwind, trying to stay tucked in and smooth.
10 min slow oscillations from very slow <50 rpm to max smooth rpm ~120 and back
10 min cooldown.
Total 60 minutes, plus some yoga, and core. See plank times later.
Here's what I want explained. Once I got dialed in, I was at about 88 rpm pretty steady, with my heart rate pretty steady at 118 plus or minus a couple beats, and it was like that for 20 minutes. Then, at the 30 minute mark, or 20 minutes into my set, my heart rate dropped like a rock. Within a minute it was down to 110, then stayed around 112 or so for the last 10 minutes of my set. Same rpm, same effort, same postion. WFT? If I hadn't been watching the monitor I'd have figured something had gone wrong. About the same time I stopped sweating as much. I didn't know whether to gear up and drive the heart rate back up or what. In the end I decided to stay in the same gear, same rpm, and watch to see what happened. Which was pretty much nothing. In the end I stopped the set because my calves where starting to get a bit twitchy and feeling precrampish. I mostly ignored a strong case of tingly butt, stayed focussed on watching heart rate and rpm, and tried to spin smooth.
The other odd thing was during the cool down, I was actually starting to get a bit of a chill, which has never happened before. By this time, sitting up and pedalling easy, about 75 or 80 rpm, my heart rate was mid-80's.
Front 61 seconds
Left 42 seconds
Right 38 seconds