[Brian Bauer]

a mistake that it took me a long time to figure out was: Zone 1 means easy all the time, not easy +segments of hard = an easy Z1 avg.  my mistake was constantly thinking “I’ll run the whole way up this hill…a few moments above Z1 doesn’t matter as long as the whole run averages out to Z1″….those moments can stack up and accumulate to ~20% of your Z1 run.   It took a segment of periodization for it to click ” hard means hard, easy means easy”…cheating your easy day impacts your hard day.  as I am mainly a trail runner, on easy Z1 days I now have no problem walking over the crest of hills to ensure that my HR stays Z1.