Our muscles use different energy sources under different intensities of effort. When you really stress your body and reach the limit of your aerobic fitness, your muscles start using anaerobic sources (this usually starts happening when your heart starts beating at round about 82-83% of your max heart rate), which leads to lactic acid build-up (the burning sensation in your legs), causing damage to the muscles and other side effects.
When you know where these limits are, then it's easier to know when to slow down and when to push. The higher your aerobic fitness level, the more you can push and still use aerobic energy.
The secret to improving your cycling condition is to balance your overload training and rest and recovery i.e knowing when to train hard and when to rest and recover. The only accurate way to do this is to use a heart rate monitor to plot your condition.
A decade ago no one in cycling had ever heard of them. Now bike racers around the world, from Lance Armstrong to local hotshots and time trialists, consider them indispensable for training and competition.
And no wonder. Heart rate monitors precisely measure the intensity of your activity and thus help you to avoid expending too much - or too little - energy.
The strength of your heart is the most important reason to maintain fitness; fortunately, it is one of the easiest fitness goals to achieve. The heart is a muscle. The heart is always functioning and, therefore, maintaining itself, unfortunately at a relativly low level in many people. But, like any muscle, when periods of exercise are applied regularly, its capacity will gradually increase so that it can deal with new tasks without strain.
If you work regularly at certain levels of intensity as measured by your heart rate, certain improvements in your fitness levels will occur - from toning muscles or losing weight to building a stronger heart or developing peak performance. These levels of effort are called Target Heart Rate Zones. Here's what they look like on a chart:
Target Heart Rate Zone
Percentage of Maximum Heart Rate
50 - 60 % ---------- Moderate Activity Zone
60 - 70 % ---------- Weight Management Zone
70 - 80 % ---------- Aerobic Training Zone
80 - 100 % -------- Competitive Training Zone
You must determine your indvidual Target Heart Rate Zone first before you start training. To determine your maximum heart rate, you can do it in one of two ways.
1. Having it tested at a lab or gym that have the facilities.
2. The easiest option is to estimate your maximum heart rate based on a formula (note that this is not your true max. heart rate) which has been established, take the number 220, and subtract your age in years. eg. If you're 45 then it's 220 - 45 = 175. So your max. heart rate is 175 bpm (beats per min.)
So Nicholas, training with a heart rate monitor has many advantages. It's going to help you train properly. You will be able to establish your diferent fitness levels. You will be able to train at certain intensities without guessing. This means that if you want to improve your endurance levels, for example, you can set upper and lower limits on your monitor and train within those limits. Your two hour training session gains much more meaning now.
There are many good monitors out there that are not so expensive, and offer many of the features of more expensive models.
(Part of this post was taken from the cyclelab.com website and sacycling mag. Thanks to Andrew McLean and Gary Beneke)