Bret

AM - Workout - 3 x mile with a 2 min rest - 1.5 mile warm up and about a mile or so cool down.  Did these right at threshold and averaged around 7:10 at the High School.  The first two were entirely in the route we run around the perimeter of the parking lots for the middle school and high school which is almost exactly 1 mile - and pretty flat.  I did part of the last one around the middle school track. It was a good effort - 7:06, 7:14 and 7:13.  Challenging to stay in that sub threshold/threshold zone, I had my Garmin with an alarm at 161 HR (threshold is likely 162 or 163) which would alert me to not to press too much more and ease a little bit, so I was pleased that I did not blowup and was able to maintain.  The first one was probably too aggressive but my HR was not pushed for the first half of that one either.  By the time I was tired - the HR was already up on the second and third reps.  

Couple of observations - Threshold HR for me has been mostly the same for at least the last 13 years or more. I would have thought it would have gone down.   Second observation - my threshold pace although probably age-appropriate is significantly slower than it was 13 years ago - by probably 45 second per mile.  Third observation - I still like doing these workouts.  They challenge me and I feel good that I can still do them.