When I purchased my heart rate monitor almost three years ago, it was an impulse buy. Look! A heart rate monitor! I want it! I NEED it!

That's how I come across many things in life. My car. My cats. My bike. The year 2005 in its entirety.

I hear it's called impulsive. I like to call it spontaneous. I sleep better that way.

And so I bought my Polar heart rate monitor. And it sat stagnant in a drawer for approximately an entire spring, summer and fall.

What? You mean I have to use it? Oh. Intriguing. Tell me more.

I finally picked it up in 2006 and read the directions after having spent six months training for my first marathon. Obviously I didn't need it for my marathon. I needed it after. I began using it religiously after that, even charting my average and maximum heart rates during each training run.

It was so cool, all of those numbers and all of that scientific information!

I will admit, though, that while I utilized my trusty heart rate monitor each and every time I laced up my shoes, I still wasn't quite sure the point.

Sure, I can now see that once my heart rate reaches somewhere around 194, I'm going to die, but that's all I've accomplished.

And since I snagged the Garmin, I've given up on the heart rate monitor. Too much technology strapped to my body. But over the weekend, we were discussing lactic thresholds and training according to heart rate zones and it piqued my interest.

You mean, it serves a purpose? Ooooooh. Continue.

Only problem is, what the hell is a lactic threshold, and how to I measure it accurately? I feel highly inadequate in my knowledge of heart rates. All I know is that I have one, and it's still beating.

These are the questions I need answered: What are my zones? How do I determine them? What do they mean? How do I improve my lactic threshold? Can I borrow $50?

Thanks in advance for your cooperation.

(XT4, IM Able, Erin - I'm looking at YOU).