An RBR reader writes: “I have been trying to calculate my heart rate for different training zones. I’m confused. Some authorities say to base the percentages on max heart rate while others suggest calculating from lactate threshold. One book says I should get a lab test to truly find my max HR. Can you simplify this mess?”
True confession: all these heart rate formulas confuse me, too. If there were a "perfect" range for training and recovery rides, it seems like the experts would agree. In fact, no such ideal heart rate exists. That's because heart rate for a given power output varies from day to day depending on your state of hydration, mental condition, whether you're overtrained or fresh, and environmental conditions such as heat and humidity.
There’s nothing wrong with using a heart rate monitor if you understand its limitations. But, ideally, it should be used in combination with perceived exertion and a power meter. A power meter can be invaluable for hard training because it provides an objective look at how hard you’re truly going.
Base exercise zones on your lactate threshold rather than on your max heart rate. LT corresponds to the highest average heart rate you can maintain for an hour. You can find it without going to your painful maximum, but medical supervision is still suggested.
Here’s one way to find your LT. Ride a 10-mile loop at a hard pace. Use a heart monitor that averages heart rate for the distance or just check it occasionally to see where HR settles. You'll quickly find that you can maintain a given HR fairly easily, but if you go a few beats higher you'll start panting and be unable to control your breathing.
For example, I can time trial (at an elevation of 6,000 feet) at a HR of 160-163 bpm. But if I go to 165 I blow up pretty quickly. Trial and error will reveal the HR you can maintain.
Three simple exercise zones based on your LT heart rate are sufficient. Recovery takes place about 40 beats below LT, endurance is built on rides about 25 beats below, and "breakthrough" training should be done from 10 beats below to about 5 beats above. These are rough guidelines, but they seem to work for most riders.
The real key to determining training intensity is to rely on your perceived exertion. For instance, easy rides should be so easy that you don't feel much pressure on the pedals through your feet. They should be, in the words of cycling coach Skip Hamilton (and you’ve surely heard me use this phrase before) "guilt-producingly slow." The idea is to take a walk on the bike.
Hard efforts, such as intervals and climbing, should be at the limit separating steady-but-labored breathing from panting and gasping. Experiment to find that boundary.