Calculating Target Heart Rate

First and foremost!!! I'm not a doctor...(Please try to refrain from inappropriate comments), just an information provider! Always consult your physician prior to beginning an exercise program! Okay, now that the disclaimer is out of the way...let's proceed!

So last week I touched base regarding the myth of the "Fat Burning Zone." The take home message was to realize that you need a mixture of cardio at various intensities and low intensity training is not the magic formula to fat loss.

Great! So now what?

First we need to know how to calculate our target heart rate. Our two options are the "Age Based Formula" and the "Karvonen Formula."

The Age Based Formula is rather simple. Subtract your age from 220 which give us an estimated maximum heart rate (MHR). Next, multiply the estimated MHR by 60 to 80%.

Hypothetically, let's say a 20 year old female wants to know 70% of her target heart rate. Here's how the calculation would look:

220 - 20 x .7 = 140 beats per minute (bpm)

While the Age Based Formula is simple, the level of intensity is often underestimated with this approach. The more common and accurate method used is the "Karvonen Formula."

The Karvonen Formula involves a 2 step process. The key distinction is the use of "Heart Rate Reserve (HRR) in the calculation." To find our HRR, subtract your age and resting heart rate (RHR) from 220:

Step 1: 220 - age - RHR = HRR

Now, using our 20 year old female, let's say her RHR is 60 bpm. This would give her a HRR of 140 bpm:

Step 1: 220 - 20 - 60 = 140 bpm

For step 2, we multiply 70% to the HRR then add her resting heart rate back in:

Step 2: HRR x Target % + RHR = Target HR

140 x .7 + 60 = 158 bpm

See the difference? With the age based formula, 70% of her target heart rate would be 140 bpm compared to 158 bpm using the Karvonen Formula. This makes a difference of 18 bpm. Plus, 140 bpm would only be 58% of target HR with the Karvonen Formula...pretty significant!

For quick reference, here's both steps of Karvonen Formula together:

Step 1: 220 - age - RHR = HRR

Step 2: HRR x Target % + RHR = Target HR

Now that we know how to calculate our target heart rate, next time we will discuss training at different zones and how to implement various intensities into your weekly cardio routine.

Stay Tuned!