New Running Plateau

OK, I'm braggin a little here....  But I want to illustrate what a run-focus can do...

I've been 100% focused on running since my last triathlon (70.3 on 8/2/08), putting in 35-40 miles on 5 runs per week, preparing for a marathon on 11/1.  Most of the miles (80%+) are Z1/Z2, but have included weekly tempo runs (Z3/Z4) of various lengths (3-5mi) and typically in the 7:15-7:30 range.  Oh, and of course I've been doing 3 long runs per month.

Last night I embarked on my tempo run intending on 2x3mi with 0.5mi jog between. I was a little tired and had some nagging stiffness in my legs.  The warm-up mile was uncomfortable (aren't they always!?).  I was thinking of shortening or bagging the tempo session altogether and just take it easy for a few miles.  Anyways, I did decide to start it at least and see how it went.  Well.... the 3-mile sets were done at 6:51 w/AHR of 164 bpm (LTHR = 171).  This is about 25-30 seconds per mile faster and a few beats per minute slower than my "typical" tempo runs...

I'd say this is a step change in my running performance.  Earlier season open run races include a 1:36 1/2M and a 21:23 5k.  Perhaps these PR's are soft given my fitness today.