You should know some basic rules when you start to use a Polar heart rate monitor.
First of all, it is essential to know that your heart rate is affected by several internal and external parameters. It takes months (if not years) to get enough experience to understand how the heart rate reacts.
Your Polar heart rate monitor works best for pacing at aerobic cycling since there is a slight delay in the pulse frequency. If you accelerate the bike to a new steady-state pace, you will reach the steady-state pulse a few minutes later.
That is important to know, and I guess that is why many riders push too hard at the beginning of intervals because they try to get their heart rate up in the target zones. But, on the other hand, using a power meter helps you maintain the correct intensity during the interval.
In short intervals with a length of fewer than 2 minutes, I will recommend that you don’t use your heart rate monitor for pacing.
How do you determine your target heart rate?
Several formulas can calculate target heart rate zones. I have seen procedures with more than six different target zones, but I usually prefer fewer.
You can easily define your target zones when you use the Karvonen formula. Remember that several factors influence the pulse, so don’t make the intervals too short.
Karvonen’s formula: Target HR = Intensity% x (Max.HR minus Min.HR) + Min-HR
Example: Calculation of Target Heart Rate
Intensity=75%, Max.HR=190, Min.HR=54
T-HR = 75% x (190 – 54) + 54
T-HR = 156