Mistake #3: Over-Interpreting HR Data
If you train regularly with a heart rate monitor, it is important to keep in mind that heart rate has significant limitations as an indicator of exercise intensity. There are many other physiological factors involved as well. An easy way to see this is to compare heart rates in outdoor versus treadmill running. Most runners have a lower heart rate when running on a treadmill than they do running outdoors at the same pace. You might think this means that running on a treadmill is easier, and that you can run faster on a treadmill. In fact, just the opposite is true. Studies have shown that runners feel better and can run faster outdoors, even though their heart rates are higher. Why? Because heart rate does not tell the whole story of exercise intensity.
Athletes who assume heart rate does tell the story often encounter problems where there really are none. They find themselves asking questions like, “Why can’t I get my heart rate up on the bike like I do when running?” and, “Why is my heart rate always higher than my friend’s even though we have the same race times?”
These are not real problems. The only real problems in training are 1) performing poorly and 2) feeling bad. If you’re performing to expectations and feeling good, or at least normal, then nothing your heart rate monitor tells you is bad.[sig:MattFitzgerald]