I was experimenting with a change in my posture. Trying to sit up straighter and hinge at my hips. This made things a bit tougher, since it was like walking with a stone my shoe.
I did the first 20′ at 183W like a good boy, and did my lactate test. I figured it would be high since I felt pretty tired and sweaty. It was…2.4mmol/l. too high. Definitely need to retreat back to 180.
So, I did that for the second 20′ piece. For some reason, probably because I was concentrating pretty hard to maintain my posture, I was really tired at the end of it.
I had a false start on piece #3. I briefly thought about just quitting, but that seemed like a wimpy thing to do. So I decided to do change it up a little bit. I bumped up the stroke rate to 22. If I was trying to maintain constant SPI, I would have been aiming for 200W, I instead aimed for about a 190, so it was a lighter stroke. It was easier to maintain better posture at this slightly higher rate, and even though my HR was higher, it felt more comfortable. The HR plateaued in the mid-150s in the last few minutes of the the piece. 
