Before you start doing any calculations, you first need to determine your baseline: Resting Heart Rate. You’ll want to do this while seated or even lying down. You want to be as relaxed as possible because we’re figuring out your heart rate at rest. Once you’re relaxed, find your pulse. I recommend taking your radial pulse. It tends to be the most convenient (and safest). You’ll find your radial pulse on the front of your wrist near the base of your thumb. See the picture below for example.
You will notice in the picture that they’re using two fingers to find the pulse. Use as many fingers as you like, but don’t use your thumb.
Once you’ve located your pulse you’ll want to count the beats per minute (BPM). When taken at rest, your BPM is your Resting Heart Rate. An alternative to counting your pulse for a minute is to take it for just 30 seconds and multiply the number by two to get your BPM.
Now that you know your Resting Heart Rate, it’s time to calculate your Max.
Max HR is most often calculated: 220 – age. This method is highly accurate regardless of fitness level, assuming you’re a man between the ages of 25 and 55. For women we prefer to use: 216 – (1.09 × age) to estimate Max HR.
Heart Rate Training Zones (HRTZ) are used to set the goal intensity of a particular exercise or circuit. The HRTZ is written as a percentage of Max HR. To convert that percentage to a usable number (beats per minute) we use the Karvonen Formula: ((HRmax − HRrest) × % intensity) + HRrest
Here’s an example of how we use the Karvonen Formula: Today’s workout includes some very short intervals and the HRTZ is 80-85%. The calculation for a 40yr old man with a Resting HR of 60 would look like this: (((220 – 40) − 60) × .80) + 60 for the minimum and (((220 – 40) − 60) × .85) + 60 for the maximum of the range. The calculation for a 40yr old woman with a Resting HR of 60 would look like this: ((216 – (1.09 x 40) − 60) × .80) + 60 for the minimum and ((216 – (1.09 x 40) − 60) × .85) + 60 for the maximum of the range.
The woman in our example would try to maintain 150-156bpm. The man in our example would try to maintain 156-162bpm.