Have a Heart - Page 2
In a nutshell, you want to train at varying levels of intensity to accomplish different things. You can gauge these intensity levels using your own feedback and experience (trainers use the term Perceived Level of Exertion), or gauge intensity by monitoring your heart rate, which gives you the advantage of precision and eliminates a lot of subjectivity.
How do you monitor your heart rate?
Ever see someone at the trailhead after a run with two fingers held up to the carotid artery taking their pulse? Well, that's one way. I can churn my own butter too, but I'm not Amish so I'll kick it up a notch technologically speaking.
To get started, purchase a heart-rate monitor. Several manufacturers offer them, including Polar, Timex, Suunto and Nike. Monitors have two pieces, a strap you wear around your chest to capture your heart rate and a receiver, typically a watch. You can get all kinds of bells and whistles, e.g. altimeter, calories burned, PC-synch capabilities, compass and barometric pressure, but all you need is one that displays your heart rate and the time.
Now, let's splash some water on our faces and learn how to use this new toy. During HRT you will target various intensity training zones, sometimes keeping your heart rate within a certain zone to build aerobic capacity, other times seeking a more vigorous zone to build speed. These zones can be calculated using two main methods: maximum heart rate and lactate threshold.
Maximum heart rate
You may have heard that to find your maximum heart rate you subtract your age from 220. Actually, this method is a wild guess, like estimating your shoe size is the same distance from your elbow to your wrist. The equation was uncovered in the 1930s by finding the maximum heart rate of a variety of individuals, some smokers, some trained, some sick and so forth, and then a line was drawn down the middle to find an average of the general population. Purge that equation from your memory.
The most reliable way to determine your absolute maximum heart rate is to run till you have a heart attack, but since that ruins the weekend, we're going to approximate it using a far more accurate method called lactate threshold (LT). Put a cool washcloth on your head, this gets more involved than the 220-minus-age estimate.
So what is lactate threshold? Well, it all has to do with something you may have heard of: lactic acid. During low-intensity exercise, your muscles produce lactate (commonly referred to as lactic acid, although chemically different, close enough for our discussions), and your body absorbs it back, keeping the overall concentration in the blood low. As your exercise intensity increases, your muscles produce more lactate than your body can absorb and the concentration in your blood goes up.
This point where the body can't keep up with the lactate production is called the lactate threshold and is the highest exercise intensity that a person can maintain for about 30 minutes. The more time you train above this point, the greater the imbalance between what your body can absorb and what your muscles are producing, and eventually it will cause you to slow or stop.