HR zonesIf you’re just using “220-age” as the only variable in finding out what your heart rate should be during exercise, there’s a good likelihood you’re missing the mark – big time.  By adding a few more variables to the equation, you can ensure you’re working out in a more accurate target zone!

The Karvonen Formula:  Finding your target heart rate!

Target Heart Rate = ((max HR − resting HR) × %Intensity) + resting HR 

Oh no!  It’s math!!  Although it might look complicated at first glance, here’s a key to finding the numbers in the equation and then let you can the calculator do the rest!!

  • “Max HR” refers to maximum heart rate and is most often found with the 220-age formula.  A more accurate formula is 208 – (0.7 x age).
  • “Resting HR” is your heart rate at rest – most accurately taken first thing in the morning before rising from bed or after a prolonged period of rest and without the influence of variables like a recent meal, exercise, smoking, caffeine or stress.

Here’s how to take your heart rate:

Radial Pulse (wrist) – place your index and middle fingers together on the opposite wrist, about 1/2 inch to the inside of the joint, in line with the index finger. Once you find a pulse, count the number of beats you feel within a one minute period.

Carotid Pulse (neck) – place your index and third fingers on either side of the neck.  You’ll find it close to the middle of the neck about 2″ below the jawline. Count the number of beats for a minute.

Here’s the final number for the equation, also dependent on you and your goals…

  • “% Intensity” refers to the percentage of maximum (100%) intensity you will work in during exercise.  Selecting a bottom and top end of your target intensity can give you a heart rate “zone” to stay within during the session (75-80% as an example).

Let’s try out the Karvonen Formula using a 45 year old with a resting heart rate of 62 who has a target intensity of 80-85%…

Here’s the formula again!  

Target Heart Rate = ((max HR − resting HR) × %Intensity) + resting HR

First, we need to find the Max HR for this 45 year old:  208 – (0.7 – 45) = 176.5

Target HR for 80% intensity = ((176.5-62) x .8) + 62 = 153.6 or 154 beats/min

Target HR for 85% intensity = ((176.5-62) x .85) + 62 = 159 beats/min

We now know that the zone for this person is 154-159!  

Now, just out of curiosity, what would the old 220-age formula multiplied by .8 and .85 for intenisty give us for this 45 year old??  140-149 beats/min!  Very different!

Find your resting heart rate and then use the Karvonen Formula to determine your target cardio training zones!  Have you been training on target?!   The photo above is my age, resting HR and target HR zones using the free app “HR Zones – Target Heart Rate Zone” just in case you’re interested!