A fellow runner recently suggested that I purchase one of those fancy heart rate monitor wrist watches, to help me train for a Spring marathon. How can such a gadget help me run better, faster and stronger? - Bah-Bumping in San Fran
You have come to the right place for an answer to this question, in fact, I consider myself uniquely capable to respond based on two significant qualities that I possess.
First, I am a "gadget head". I access the Internet regularly through my digital cell phone; I wear a computer watch which links to both my personal information manager software on my handheld palmtop computer and the latest news and weather on the Internet. My car has all the buttons, knobs and readouts of a 767-cockpit dashboard. If it's a high-tech gadget, I've probably got it, and that includes my heart rate monitor which I use every day that I run.
The second quality, which gives me authoritative rights, as a professional respondent to your query, is less technical: I have a heart. That slightly bulbous excessively bloody ever contracting organ that beats continuously in my abdomen is the thing we have in common, that I monitor, thanks to the electric energy coursing through my body and detected by my HRM (heart rate monitor).
The simple answer to "How does monitoring a fist-sized muscle improve my running performance?" is thus: The less your heart has to squirt oxygen around your tubing, the more efficient a runner you are and the better, faster and stronger you'll run.
So, by ensuring that most of your training runs are done within a certain zone, let's call it the "aerobic target zone" (for lack of a better term), then the lower your resting heart rate will be and the more efficient a distance runner you'll become.
Now, if you agree with my logic, you'll come to understand how your age and current maximum heart rate (the number of beats per minute your heart can pump without exploding) relates to what your "aerobic target zone" should be. For example, at 40 years of age, and with a maximum recorded heart rate of 195 beats per minute, my "target zone" for my typical non-speed training days is between 70% and 85% of my maximum, that is: 136 to 165 beats per minute.
So, with heart rate monitor firmly in place, I run my daily five to eight miles below 165 and above 136 beats per minute, and my heart is conditioned to deal with the excesses of long duration runs, for sustained periods at a higher pace.
All of which is an extraordinary long-winded way of saying that a heart rate monitor is to your heart what free-weights are to your upper body muscles. It's a tool for training your cardiovascular system to pump blood more efficiently through your body, which in turn can help you to be a better runner.
Of course, the same can be achieved if you just "listen to your body" when you run, but speaking as an official "gadget head", it's kinda cool to keep track of your effort as you strengthen your heart.
Run long and taper.