I went to the track at the local high school and ran intervals. My hams and legs felt fine! I think I ran about the same pace as last week.
I ran two splits at 1/2 lap (1/8 mile) each. Then I ran a split at 1/4 mile, and I ended my planned splits with two more at 1/8 mile each. My recovery between splits was 1 1/2 laps or 3/8 mile. I felt fine during the intervals. To reduce the stress on my knees from running a small loop, I reversed my direction after the 3rd split.
I wore my wife's HR monitor. At the end of a 1/8 mile, my HR was only up to 101 68% of max). At the end of the 1/4 mile it was up to 106 (71%). It looks like I'd have to run a much longer lap to get close to 80%. Next week I'll wear my GPA so I'll know the pace I'm using.
The first question that came to me when I saw my HR at the end of the first split was whether the monitor was giving accurate values or not. When I'm sitting quietly, the monitor is within 1 beat of my HR taken manually. Because of this, I assume the monitor was giving good readings. I know I have very good oxygen capacity, and that probably is why my HR didn't go very high at the end of the splits. I was running pretty fast, but I wasn't breathing heavily.
Next week will be my last session for intervals. I want to run hills for three weeks, followed by a 13 mile long run the next week, and then a two-week taper to the race on April 21. The course for the Salt Lake City half-marathon has a 2/3 mile steep descent off the east bench (27th East to 23rd East), as well as a few small hills, and I want to train for them.