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Target Heart Rate - Please Help

I have been up and down many websites, and used the search for old threads, and would love to have an accuarte answer for:

1 - If I am 37 years old what is my target heart rate to burn fat? Is it safe to use 220 - 37 = 183, and I must be at 80% - 90% of target for duration of exercise which makes it 146 - 164.

2 - How long should I exercise during that range to get maximum fat burning potential?

3 - What happens if I get my heart rate up to 170 will I still be as efficient at burning fat? or better ? or worse ?

I would really appreciate your guidance !!!!

Thu. Feb 7, 7:18pm

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I'm not convinced you did much research if you're under the impression that 80-90% is the fat-burning zone. There are charts all over the gym and every piece of cardio equipment that give you the answer.

1 - your fat-burning zone is NOT 80-90% - that's about when we go anaerobic, which is the opposite of fat-burning. You want to be at 55-65%, so about 100-120bpm.

2 - the first 100 calories (approx 15 minutes) comes mostly from your glycogen stores and then it kicks over to fat.

3 - see answer to #1.

There's a test called the VO2 Max (VO2 = volume of oxygen), where your oxygen output is measured on a treadmill in correlation to your heartrate. It'll show your ideal fat-burning zone, including how many total calories you burn and how many of those are from fat v. other sources. Really good gyms (not ordinary chains) offer this sort of service and it costs $100-200 depending on where you live.

Thursday, February 07, 2008, 7:31 PM

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OP here this is why there is confusion.

Thanks pp but this is one of the examples that I had used in calculating. Then further to this I read that it is 80% - 90%. I have also see at the gym on the machines you are making reference to as being at the 50% range.
This is one formula for target heart rate that I used:

In the previous step, you used the Karvonen Formula to calculate the lower end of your THR zone. Now you'll use the same formula to calculate the higher end. Once again, all you need is your age and your resting heart rate:

220 - (your age) = Max Heart Rate (MaxHR)
MaxHR - (resting heart rate) = Heart Rate Reserve (HRR)
HRR x 85% = training range %
training range % + RHR = high end of your THR zone

The following example shows the high end of a THR for a 35 year old person with a resting heart rate of 60 bpm:

220 - 35 = 185
185 - 60 = 125
125 x 85%= 106.25
106.25 + 60 = 166 beats per minute

You should now have two numbers that will range somewhere between 120-180 beats per minute, depending on your age and resting heart rate.

This is the other formula:

To determine your fat burning heart rate zone you will first need to find your resting heart rate, or RHR. Your resting heart rate is actually an indicator of your overall fitness level. To find your RHR, simply take your pulse for 1 full minute. Count each heartbeat for your total Beats Per Minute or BPM. To find your pulse, take your index and middle finger and place them directly under your ear. Simply slide your fingers down and over to your jawbone. Directly under your jawbone, you will feel your pulse. Now count each beat for one full minute. A normal resting heart rate should be between 60-100 beats per minute. If your resting heart rate is more than 100 beats per minute, you should schedule a check up with your health care provider.

You can also check your heart rate by placing your index and middle finger under the base of the thumb on the opposite wrist. Again, count each pulse for one full minute. Now, here is the formula used for finding your target heart range.Take the number 220 and subtract from that number your age. For example 220-40= 180. Now, take the answer (in this case 180) and multiply it by .55. In this example the answer is 99. This means that your low target heart rate is 99 beats per minute. Now, take the same number- 180 and multiply it by .85. The result in this example is 157. This means that the maximum number of beats per minute would be 157 to ensure that you are burning fat and staying within your target heart rate.

Knowing your ideal fat burning heart rate will help you lose more fat by making your body burn fat while exercising instead of burning carbohydrates or protein.

Thursday, February 07, 2008, 7:57 PM

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The part of that I really don't understand is burning fat v. carbs v. protein. Your body doesn't take the food straight from your stomach for immediate use. You burn glycogen ("muscle sugar", energy) and stored fat. As your heartrate goes further beyond the 65% mark, your body uses less of your fat stores - something to do with oxidation, I forget exactly. I forget at which point your body starts eating its own muscle mass as it relates to exercise, but that's what resistance training helps with.

I've seen people's VO2 max results. In their fat-burning range, they're maybe using 7 calories per minute and 5.8 of them are from fat. Then you see their heartrate at the top of their range and burning 11 calories per minute, but only about 3.5 of those calories are from fat. That doesn't mean the high intensity stuff isn't worth doing - it increases endurance and capacity, gives a great metabolic boost for an extended period of time, etc. But the long and short of it is that walking is pretty much the best thing you can do to lose weight because it's naturally in the fat-burning range for most people and is a sustainable habit to form.

By the way, I've tried a bunch of formulas and they always produce results within 2bpm of each other. And they were wrong - I've been 5bpm above my official 100% and my heart didn't explode.

Thursday, February 07, 2008, 8:31 PM

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I've done swimming where my heart is in the fat burning age, and never lost an inch. I switched to running, and kept diet the exact same, and lost weight.

You wind up buring more cals than your rmr after stopping anaerobic exercise, than you do with aerobic.

Thursday, February 07, 2008, 11:55 PM

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Op here.
Thank you for the feedback. I am not new to exercising, but have put on about 10lbs due to some life changes over te last year. Before I put on the weight, I was exercising 45 min everyday and doing resistance machines, and was at my ideal weight and BMI and a size 4.
When I started back at the gym 4 months ago (after a 6 month hiatus) I counted every calorie (for a total of 1200 / day), and worked out on tread and elliptical for 1 hr with a hr of between 145 - 170 and lost not 1 lb.

I guess I was pushing myself into the anaerobic side vs fat burning. I never had to actually calculate any of this before, I just exercised and lost weight and then maintained.

Friday, February 08, 2008, 9:20 AM

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Just to throw another monkey wrench in the gears, 220-age isn't all that accurate- it's a good baseline, but some people have a higher or lower max HR than the equation would suggest- I'm 37, and my max HR should be 183, but it's actually 193.

There are ways to test your true max HR- you can search for them online, or you can see if your gym has a personal trainer on staff to help you out.

If you haven't already, you should get yourself an HR monitor- it's so much more convenient than using the hand grips and it gives you much more accurate data about calories burned, etc. I've found the calorie calculator on the treadmill to be off by more than 100 calories.

Friday, February 08, 2008, 9:27 AM

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6:37 Thank you! I too was wondering that after just responding to the other thread about whining..yada yada yada, some people like to just complain!
this was a great informative thread,thanks

Friday, February 08, 2008, 10:13 PM

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Regarding the 7:57 copy/paste info...
Target Heart Rate is not the same as the Fat-Burning Zone. I think that's where all the confusion stems from.

Friday, February 08, 2008, 11:23 PM

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