[Scott Johnston]

Great question!  It’s hard to keep in the HR zone 2 when you’re trying to stay close to the top of it.  Short bumps up into Z3 during your aerobic base runs will not have a negative effect on the aerobic base you are building.  I’m glad you are seeing gains. Don’t lose sleep over this.  Now if you spent a continuous 15-30min in Z3 that’d probably have some negative effect.  From the sounds of your note it sounds to me like you’re doing this very well.    Keep it up and retest your AeT after 6-8 weeks and see if your AeT hasn’t moved up 5-10 bpm as well as your pace.

Scott