In my last post, I went over why I started training using heart rate zones based on maximum heart rate. I wanted to build a good solid “base” so I could continue to improve throughout the year and long term. I also wanted to be very efficient at burning fat. In 2013, for both the bike and run, I trained almost exclusively in Zone 2. I was in the process of becoming fat adapted so I did very little speed work. However, looking back, I should have done some interval or speed work.
So what the heck is training zones anyway?