Saturday, June 25, 2011

Determining Your Maximum Heart Rate, Cardio Zone, and Fat Burning Zone

The following formula is for determining the rough estimate of your maximum heart rate. While exercising, you should try not to exceed this number, as it puts too much stress on your heart

Max. HR = 220 - your age

For example: A 34 year old's maximum heart rate is: 220 - 34 = 186 bpm
If that 34 year old wants to work out in the cardio zone (70-85% max. hr), meaning her body uses glycogen as the majority percentage of fuel, she would use the following formulas:
  • The low end of the cardio zone means that the heart is beating at 70% of it's max.
    • (220 - your age) x 0.7 = low end of cardio zone
  • The high end of the cardio zone means that the heart is beating at 85% of it's max.
    • (220 - your age) x 0.85 = high end of cardio zone
For our 34 year old, the formulas would yield the following results:
  • Low end: 186 bpm x 0.7 = 130.2 bpm
  • High end: 186 bpm x 0.85 = 158.1 bpm
If our 34 year old wants to exercise in the cardio zone, she should keep her heart rate between 130 and 158 beats per minute.

If our 34 year old want to work out in the fat-burning zone (55-70% max. hr), meaning her body uses fat as the majority percentage of fuel, she would use the following formulas:
  • The low end of the fat burning zone means that her heart is beating at 55% of it's max.
    • (220 - her age) x 0.55 = low end of fat burning zone
  • The high end of the fat burning zone means that her heart is beating at 70% of it's max.
    • (220 - her age) x 0.70 = high end of fat burning zone
For our 34 year old, the formulas would yield the following results:
  • Low end: 186 bpm x 0.55 = 102.3 bpm
  • High end: 186 bpm x 0.7 = 130.2 bpm
If our 34 year old wants to exercise in the fat burning zone, she should keep her heart rate between 102 and 130 bpm.

You might have noticed that the upper end of the fat burning zone and the lower end of the cardio zone are the exact same number. Maximum heart rate and exercise zones are estimates. They outline a general range that identifies what our bodies do during different intensities of work. When our 34 year old exercises and keeps her heart rate at the upper end of fat burning and lower end of cardio, her body uses nearly equal amounts fat and glycogen as fuel.

Source: Fitness: The Complete Guide.  Fredrick C. Hatfield, Ph.D.  International Sports Science Association, Carpinteria, CA.  2010

Edited by Natalie at 4:08 PM

7 comments:

Wade said...

220 - your age is a reasonable starting point, but it's just a general average. People who are not fit, have health problems or have other risk factors may have a max HR less than this formula indicates. Conversely fit individuals have higher max rates. For instance, I am a 52YO active male; my tested and verified max rate is 178, resting rate is 42.

Tiffany said...

This is a great post showing the math, but unfortunately the newest research is that the "fat burning zone" is a myth. Not trying to be rude or argumentative, but the "newest theory" is that high intensity interval training is the best way to burn fat...at least this is what I've been reading. Maybe a post on the benefits of high intensity? I myself am redefining my own workouts to include less traditional cardio and more interval training to boost my fat loss.
There are lots of articles out there, here is one though that gives some good info...
http://www.active.com/triathlon/Articles/The-Myth-of-the-Fat-burning-Zone.htm

Again, I'm not trying to be argumentative, just trying to put a thought out there....

Tiffany said...

One other thing, this is a good guide to give you a general idea of where you should be while training, I just think the "fat burning zone" is confusing to the average person who is just getting into exercising...

Kaitlin said...
This comment has been removed by the author.
Kaitlin said...

Thank you for this detailed post! This just confirms results that have ACTUALLY happened for me by following your advice! It's nice to shed this weight!

Julia said...

my resting heart rate is 45, which makes it challenging to increase it to the fat and cardio zones (I am 52 and active female) How do I account for that?

Natalie said...

Hi Julia! Great question. The above formula is, as I said, a general formula. A more accurate range can be found using the Karvonen Formula, which takes your resting heart rate into account. Someone with a low resting heart rate has more room to increase their heart rate than someone with a higher resting heart rate. You can go here to find your range based on your age and resting HR.
http://www.briancalkins.com/HeartRate.htm