Heart rate training

First blog of 2011! I'm massively behind, I only wish that i blogged as often as I think about blogging, because if I did then this blog would be EPIC!
I'm not going to do that whole random catching up thing, I'm trying to work more topically and go on fewer whimsical rants this year.
So, today I started experimenting with HR zone training. Santa brought me my very first heart rate monitor (it's a polar RS 300x) and it became quite apparent that while my times mean I am not racing blisteringly fast, my heart sure is. On an average (even a slower than average) run my heart was doing around 165-169 bpm, or even higher! That's around 85% of my maximum heart rate (I haven't had any fancy tests, I'm really just working that back from a few formulas based on age and gender) and 85% is basically, going pretty bloody hard. I don't feel super uncomfortable at that rate, but it puts me squarely in what's called the anaerobic zone, which is a hard effort, and where (depending on who you ask) my body is using stored glycogen or, failing that, lean muscle tissue. I run very early in the morning, so I probably don't have much stored glycogen, and I worked very hard to get my muscle, so I'd rather my body didn't eat it, thank you very much.
So, I want to be working at around 70% of my max, in the aerobic zone, so for me the golden number is 150bpm. I am so far letting myself go five beats either way, so basically am trying to stay within 145-155bpm.
This is slllloooooowwwwwwwwww. Ten minute kilometres slow. Walking to get it down, and super, super gently jogging between walk breaks ( Actually, I need to have a chat about walk breaks, but I'm still in the info gathering stage there, so it's another story). Painfully, crazy slow.
The goal of this type of training is that, eventually, my heart will get bigger and stronger. My body will use fat for fuel at this lower heart range (which is awesome, because this is the year that I'm going to bmi 25, people!) and slowly, gradually, I'll be able to go faster at that same, 145-155bpm rate of effort.
So, go slow now, go fast later.
It all sounds suitably science-y. I will admit to being a little sceptical.
Right now, however, this type of training is perfect for me. Summer is peaking here in Melbourne (currently the humidity is 95% or higher EVERY DAY, having to be super careful with hydration)and it's hot and yucky. I'm having a few persistent niggly pseudo-injuries, and this type of training is an in-built check rein to prevent me going too fast or too hard. I also feel a lot fresher after this type of workout, because I haven't completely flogged myself. I do worry that I'm not working hard enough, but I'm going to just have to get over that.
So, this is the beginning of the experiment, and I'm really looking forward to testing the science behind this theory.