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TOPIC: Heart Rate Monitors- How accurate are the calories burned?

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August 31, 2011 10:32 AM
QUOTE:

QUOTE:

The HRM Is definately More accurate than the Machines. the machines don't take into account your fitness level. they base it on the average person, which in todays society isn't very fit.


Fitness level has little or no effect on the calories burned at any comparable intensity level.

If a 60 yr old who weighs 150 lbs and an Olympic runner who weighs 150lb run at 6 mph, they will both burn roughly the same number of calories. It will feel much easier to one than the other, but it's the "absolute" intensity that determines calorie burn, not the "relative" intensity.


Not true, your level of fitness will determine your level of effort. In your example a fit olympic runner could likely run at an easy pace 6MPH for an hour at less that 50% of his Maximum HR. While a 60 year old that is out of shape performing the same exercise might exceed 80-90% of his/her Maximum HR.

Had you said that the two people in your example both worked for the same amount of time at the same level of physical effort which would mean that their average heart rate over that time was equal then you would be correct.
  10207017
August 31, 2011 10:37 AM
QUOTE:

QUOTE:

If you have properly setup your HR Zones on your HR Monitor then it should be much more accurate than the machine. Like it's already been stated, the machine does not account for Genetics, Fitness Level, etc.


Heart rate "zones" do not play any role in how many calories you burn--other than the fact that working harder burns more calories.

Genetics--at least not for the average person-- and fitness level don't really factor in either.


HR Zones absolutely play a role in how many calories you burn. My Max HR is roughly 185 which is about 8 BPM higher than what most machines would have posted on them. For me to workout at 75% of my max to burn roughly 14 calories per minute I need to maintain a HR above 139BPM. At 50% of my Max and burning roughly half the number of calories per minute my average HR needs to be around 93BPM for the duration of the workout.

If I used the charts on most machines my max HR is 175 which means 88BPM to maintain 50% or 131 for 75%.

Google is your friend here...

ETA: To get to my point. If your HR zones are setup wrong because you did not properly calculate your Max HR then you will not be able to accuratly calculate your caloric burn per minute based on average HR. Genetics role in this is that not everyone's Max HR can be calculated based on 220-Age. Some people, for whatever reason, just have a higher or lower max than others and it has everything to do with genetics.
Edited by batlou On August 31, 2011 10:39 AM
  10207017
August 31, 2011 10:48 AM
QUOTE:

it is really frustrating to put that much effort and intensity into an hour of my life, and only get 400 extra calories from it. grr!!!!explode


Totally agreed. I had one TKD class where I was drenched with sweat, panting and my face was absolutely purple, and I almost threw my HRM across the room when I checked it and it read only 235 calories! AUGHHHHHH!!!
August 31, 2011 3:12 PM
QUOTE:

QUOTE:

QUOTE:

The HRM Is definately More accurate than the Machines. the machines don't take into account your fitness level. they base it on the average person, which in todays society isn't very fit.


Fitness level has little or no effect on the calories burned at any comparable intensity level.

If a 60 yr old who weighs 150 lbs and an Olympic runner who weighs 150lb run at 6 mph, they will both burn roughly the same number of calories. It will feel much easier to one than the other, but it's the "absolute" intensity that determines calorie burn, not the "relative" intensity.


Not true, your level of fitness will determine your level of effort. In your example a fit olympic runner could likely run at an easy pace 6MPH for an hour at less that 50% of his Maximum HR. While a 60 year old that is out of shape performing the same exercise might exceed 80-90% of his/her Maximum HR.

Had you said that the two people in your example both worked for the same amount of time at the same level of physical effort which would mean that their average heart rate over that time was equal then you would be correct.


I am referring to absolute intensity, i.e. oxygen uptake, not relative intensity, which is percentage of maximum. Relative intensity means little when calculating rate of caloric expenditure (obviously it will affect total calories burned during a workout if one can maintain a lower intensity much longer than a very high intensity).

Caloric expenditure is based primarily on oxygen uptake and the oxygen demands for steady-state aerobic exercise are relatively constant--by that I mean that the energy cost for our example speed of 6.0 mph is roughly 10 METs. Doesn't make any difference who is doing it or their fitness level. 10 METs might be an easy effort for someone highly conditioned, with a VO2max of say 20 METS and a very difficult effort for someone with a VO2 Max of 12 METs, but the energy cost is still 10 METs. Heart rate does not make any difference in calories burned for an activity with a fixed energy cost. In the example we are using, the elite athlete might have a heart rate of 110, or 50% of HRR, the other person a heart rate of 140, or 85% of HRR. However, both are still working at 10 METs. Since the rate of calories burned is METs x body weight, if they weigh the same they will burn calories at roughly the same rate.

The ACSM metabolic equations, which are the accepted standard for this sort of thing, do not use height, age, gender, fitness level, or heart rate as factors.
August 31, 2011 3:22 PM
QUOTE:

QUOTE:

QUOTE:

If you have properly setup your HR Zones on your HR Monitor then it should be much more accurate than the machine. Like it's already been stated, the machine does not account for Genetics, Fitness Level, etc.


Heart rate "zones" do not play any role in how many calories you burn--other than the fact that working harder burns more calories.

Genetics--at least not for the average person-- and fitness level don't really factor in either.


HR Zones absolutely play a role in how many calories you burn. My Max HR is roughly 185 which is about 8 BPM higher than what most machines would have posted on them. For me to workout at 75% of my max to burn roughly 14 calories per minute I need to maintain a HR above 139BPM. At 50% of my Max and burning roughly half the number of calories per minute my average HR needs to be around 93BPM for the duration of the workout.

If I used the charts on most machines my max HR is 175 which means 88BPM to maintain 50% or 131 for 75%.

Google is your friend here...

ETA: To get to my point. If your HR zones are setup wrong because you did not properly calculate your Max HR then you will not be able to accuratly calculate your caloric burn per minute based on average HR. Genetics role in this is that not everyone's Max HR can be calculated based on 220-Age. Some people, for whatever reason, just have a higher or lower max than others and it has everything to do with genetics.


You seem to be consistently confusing relative intensity vs absolute intensity. As well as confusing the artificial construct of caloric estimation using an HRM vs the reality of determining real intensity using a metabolic cart.

HR Zones, max HR, etc are only necessary when setting up a heart rate monitor. When it comes to estimating calories, a HRM is a mathematical model that attempts to describe reality, it is not the reality itself. It's accuracy depends on whether the activity you are performing actually matches the assumptions underlying the programming of the HRM--as well as how accurately you program the variables contained in the algorithms.

Which doesn't have anything to do with my comments.

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