Methods to Calculate Fat-Burning Heart Rate Zone
Written by Yasar Shahzad Wednesday, 07 July 2010 19:26
Methods to Calculate Fat-Burning Heart Rate Zone
There are two methods to determine your target heart zone for fat burning. If you don't know your resting heart rate, you can use the "age-predicted" method. This formula takes your estimated maximum heart rate and multiplies it directly by the intensity you want to work at. If you know your resting heart rate, an even more accurate method is the Karvonnen formula. This method accurately predicts your training zone by factoring in your resting heart rate.
Method 1: The Karvonnen method (Use this formula if you know your resting heart rate)
Step 1: Determine your resting heart rate. Your resting heart rate is determined by counting your pulse (at your wrist or the side of your neck) for a full 60 seconds. A true resting heart rate should be measured in the morning as soon as you wake up and before engaging in any activity or consuming any stimulants (coffee, etc). Your resting heart rate is a fairly accurate indicator of your cardiovascular fitness level. The better your level of cardiovascular fitness, the lower your resting heart rate will be. The average resting heart rate is 72 beats per minute (bpm). If your heart rate is substantially higher than the average (80-90 bpm) it may be a sign of poor cardiovascular fitness. A resting heart rate higher than usual can also be a sign of overtraining. Low resting heart rates are usually an indicator of excellent cardiovascular fitness. Some marathon runners have resting heart rates as low as 40 bpm or less!
Step 2: Determine your estimated maximum heart rate (EMHR) Your EMHR is an estimate of how fast your heart can beat while exercising. The formula below is only an estimate of your maximum heart rate. The only way for you to know for sure what your EMHR is would be to experience a graded treadmill test. (Where they hook you up to a bunch of monitors and gradually run you faster and steeper until you literally drop from exhaustion)
The formula for estimated maximum heart rate is 220 - your age
Example: you are 30, 220 - 30 = 190 your EMHR is 190 beats per minute
Step 3: Determine your heart rate reserve (HRR) by subtracting your RHR from your EMHR
Example: your RHR is 58 bpm your MHR is 190 190 - 58 = 132 your HRR is 132 bpm
Step 4: Select an intensity range to work at based on your goals and on your personal fitness level. The target zone is between 60% and 80%
% of MHR Difficulty
60-65% moderate 65-70% somewhat hard 70-75% moderately hard 75-80% hard
Step 5: Multiply your HRR by your desired intensity range
example you are a beginner select the moderate intensity range of 60-65% multiply your HRR by 60-65% 132 X .60% = 79 132 X .65% = 86
Step 6: Add your RHR to your HRR to determine your target heart rate
79 (HRR) + 58 (RHR) = 137 (THR at 60%) 86 (HRR)+ 58 (RHR) = 144 (THR at 65%) Your target zone is 137 - 144 beats per minute
Method 2: The Age-Predicted Method
This is the simplest method of determining your target heart rate and this should be used if you don’t know your resting heart rate.
Step 1: determine your estimated maximum heart rate (MHR) The formula for maximum heart rate is 220 - your age
Example: you are 30, 220 - 30 = 190 your EMHR is 190 beats per minute
Step 2: Select an intensity range to work in based on your goals and on your personal fitness level. The target zone for the age-predicted method is 70-85% of your estimated maximum heart rate
% of MHR Difficulty
70-75% moderate (beginner) 75-80% somewhat hard (intermediate) 80-85% hard (advanced)
Step 3: Multiply your MHR by your desired intensity range Example: You are a beginner Select the moderate intensity range of 70-75% Multiply your MHR by 70-75% 190 X .70% = 133 190 X .75% = 142
An Important Note about Target Heart Rates
Regardless of which method you use, it’s important to understand that target heart rates are only guidelines – they are estimates. Heart rate estimates are usually accurate for about 70% of the population. That’s why you need to use good judgment about how the exercise feels and how your body is responding. Use common sense; if you’re working in your target heart range and it feels ridiculously easy, then don't be afraid to increase the intensity. On the other hand, if it feels incredibly difficult, don’t hesitate to decrease your intensity. After you’ve been working out for a while, you should start to develop a intuitive sense for how it feels to be in your target zone and you can use subjective measures of your intensity such as your rating of perceived exertion.
If you’ve been completely sedentary, if you’re overweight or if you’re in poor physical condition, you may need to start at an intensity level lower than your minimum target heart rate. Again, use your judgment, start slowly, and gradually increase the intensity of your workouts as you become more fit until you’re eventually in the ideal target zone.
Method 3: Perceived Exertion
Perceived exertion means that you "guess" at the intensity of your workout based on a scale of 1 to 10. According to the American College of Sports Medicine (ACSM), perceived exertion is a reliable indicator of your level of physical exertion during steady-state exercise and can therefore be used as a substitute for target heart rates. Basically, if you think your workout is “hard,” it probably is.
The scale of perceived exertion below provides you with a subjective way to quantify the intensity of your workout without having to take your pulse. Your goal is to work at a level you perceive as moderate to hard, but not extremely hard. The scale goes from 0 to 10 with zero being no work (such as sitting) and 10 being maximal (such as a 50-yard all-out sprint). Based on this scale a rating of 4 to 8 would be the ideal range for steady sustained aerobic activity for fat burning.
Rating of Perceived Exertion
0 Nothing (no work: sitting or lying)
1 very, very light
2 very light
3 light
4 moderate
5 somewhat hard
6 moderately hard
7 hard
8 very hard
9 very, very hard
10 Maximal (all out sprint)
Breathing as a measure of exercise intensity
Believe it or not, breathing is actually a very good way to estimate whether you’re working out in your target fat burning zone. If you’re in the target zone, generally, you’ll be breathing much heavier than normal, but not so heavily that you’re hyperventilating or gasping for air. You should be able to speak full sentences comfortably without having to stop and catch your breath. If you’re so out of breath that you can’t hold a conversation, or complete a sentence, then you’re probably working out of your target zone (this is known as the “talk test”). Generally, the harder you’re breathing, the higher the intensity and the more fat you'll burn, provided you can sustain the activity for the required amount of time. If you’re not breathing hard, you’re not working out hard
How to measure your heart rate during a workout
During an exercise session, you should periodically check you pulse at your wrist or neck to see if you’re within your target range. If you’re below your target heart rate, you should increase the intensity by increasing resistance, speed or incline (if applicable). If you’re above your target zone, you can decrease your intensity. Taking a full 60 second count would be impractical because it would interrupt your workout too much (You may have to stop moving to check your HR, depending on the type of activity you are doing). The solution is to use 10-second pulse counts. Simply divide your target heart rate in beats per minute by 6 to find your 10 second count:
Example: Your target heart zone is 133 - 143 Divide 133 by 6 to for your low end of range 10-second count: = 22 Divide 142 by 6 to for your high end of range 10-second count: = 24
If you want to make the $100- $150 investment, a polar heart rate monitor is the ultimate way to measure your heart rate during exercise (www.polarusa.com). A chest strap transmits your heart rate to a wrist monitor via telemetry. This allows you to workout continuously without the interruption of pausing every few minutes to take your heart rate. Most commercial quality exercise equipment is now polar compatible so the heart rate signal will be transmitted directly to the machine and you can read your heart rate on the console's readout.
