Accuracy of the F6 or F11 heart monitor

I have the F6 heart rate monitor by Polar. I am questioning the accuracy of it. I know the accuracy is "supposed" to be very good, but, I'm not sure if mine is correct. Does it lose accuracy as the battery gets low? That doesn't seem reasonable.  I burn about 700 calories doing tae bo and 600 when I walk on the tread mill each for about 50 minutes. Is this high?  I've worn it all day many times and have reported as much as 5000 calories burned. That seems like a lot considering I'm not running all day long. Help?

Well it wont give you an accurate number if worn all day because it is not designed for this. So that 5000 is wrong.

My f6 says I burn 300 calories in 30 minutes at moderate pace. Seems accurate.

I've questioned the accuracy of mine as well for the exact same reason.  According to my F6, I burn approximately 800 calories for a hours worth of ellipitical, stair climber and/or running (usually 30 minutes of two of those activities).  So, it seem like ours is relatively similar.

I think they give pretty accurate work out numbers, but they are definitely not meant for tracking a whole day. It's only meant to work when you are exercising and elevating your heart rate.

Go to one of the many sites that tell you what the expected Cal/hr of an individual exercise is, and rate it.  My rs200 underestimates based on what I should be burning.  It gives a number based on your input weight, your estimated fitness level, and your heart rate.  Unless your heart rate is way high really quick, you should probably have an underestimate. 

I have been using polar HRM's for over 10 years.  They are definitely the most accurate HR monitor you can buy.  Calories burned any machine is going to suck at... including the polar.

I have an F6 also.  It gave me readings similar to

i_will_lose_it's figures until my trainer set it for me.  I would check your settings.  They may just need to be tweaked a bit.

 

I have an F4 and I think it is giving me consistently low readings. Generally less than half the calories burned using CC's figures or the machines figures. However, I take beta blockers and other BP drugs and that has to be affecting the readings.

For instance this morning it said I burned 155 calories for 35 minutes effort on an elliptical. The machine said almost 400 and CC's light elliptical says 368. Using the exertion scale I was actually working out at a moderate level and had to have burned more than 155 calories. I've tried adjusting the age upward in hopes that the F4 will generate a higher calorie burn to no avail. If it went up it wasn't much.

I guess the only way to really calibrate my HRM is to monitor weight loss versus calorie burn. If it says I only burned 2000 calories per week for two or three weeks and I lose 5 or 6 lbs in that time frame then I'll really be convinced that it is way off and go back to using CC's numbers.

When you use heart rate monitors, the amount of calories burned is all dependent on how high you get your heart rate up.  If you get it up higher and keep it there, you will burn more calories in a shorter amount of time.  So really, it's all dependent on YOU and YOUR OWN personal rate.  If you and I were the same age/height/weight etc and worked out side by side doing the exact same exercise for the same amount of time, that doesnt mean we will burn the exact same amount of calories.  It all depends on who's heart rate overall average was higher.  That person will have burned more calories.

Hope that made sense LOL

~H~

I was thinking that for a given heart rate, say 110 someone who was 30 years old would burn fewer calories than someone who was say 90. Since the 90 year old would be working harder, e.g. over the 80% heart rate, while the 30 year old was loafing along at 60% of max HR. Am I wrong in thinking that?

This morning I was working in the moderate to high exertion rate for me. My max heart rate as measured by my cardiologist was 137 before he gave me a stronger beta blocker. Using the charts 85% of a normal 61 year old is equal to my max HR. I would think I would have to be burning more calories to get my heart rate that high.

Bobev- Depending on your medicine, it is possible that your heart rate is being regulated to help control your BP.  if this is the case your HR won't get as high as it normally would without hte medicine.  I would ask your doctor about that one though : ) BUT!

If you have the information, you can use the MET values achieved during your workout to calculate the cals burned (i'm not sure if your machine tracks the METs). 

If you can get the Metabolic Equivalent values (MET) you can use this equation to figure out how many calories you are really burning, even though your HRM doesn't pick up on it because of your [possible] HR ceiling:

Calories burned for oneminute = (METs*3.5*[weight in Kg]*5)/1000

One MET is the same as the amount of calories you burn at rest just living/breathing (in case you didn't know :)

This is often how they calculate everything from cals burned washing a car to cals burnt in pro triathletes.  If you're not sure about the METs (i know Lifecycle bicycles display METs) you can find estimates online. 

Good luck!

Thanks ilovewater! The machines I use do have METs I never knew how to utilize them. Will give it a shot in the morning and see how it compares.

thanks!

Well I gave the METs calculation a shot. The Elliptical machine I use display's METs during the workout but does not display an average METs so I have to guess it.

With age =90 and weight= 177, the F4 yielded 48 minutes, 245 calories, avg hr 98, max hr 112. This included 10 minutes of stretching & roll down/ups after 38 minutes on the elliptical.

Exertion scale was about 6-7 for most of the workout. I was talking to someone right at the end and that wasn't easy.

The Life Fitness Elliptical using manual workout where you enter just a weight was just about 380 calories (I stopped when the F4 hit 200 calories). The METs values displayed during the workout ranged from 6.1-6.8. So  I used an estimated average of 6.3. Using a weight (with clothing) of 177, 48 minutes duration the average Calorie/min = 8.9 and total calories = 337 for the 38 minutes on the elliptical.

So it does look like the F4 reads low, even trying to play with the age to get it to increase calorie burn. I don't work out on Sat's but Sunday I will try using the Fat Burn or Cardio settings on the Elliptical with age = 90 to see how that matches up with the F4 and the METs calculation.

The true values will show up on the scale. If I lose more than the calorie burn for the week shows then I'll need to adjust what I input. I don't want to overestimate calorie burn because that could lead to overeating!

good! I'm glad to know it was within reason!

I love doing work out experiments to see how the body works : )

Original Post by ilovewater:

good! I'm glad to know it was within reason!

I love doing work out experiments to see how the body works : )

that's why Doctors "practice"! Couldn't resist. Being an Engineer that is the way I figure things out as well. Besides we know our own bodies best and need to be our own advocates. More to come on Sunday and when I weigh in for the Wed J4C Challenge

Well I took another set of measurements this morning.

Using a Life Fitness Elliptical set for fat burn, age 90, weight 177 the METs value varied between 5.3 and 6.8 with peaks over 8 during high intensity interval periods. When I finished after 38 minutes (stopped at 200 cal on the F4) it read 390 calories burned. Their was still a METs display but I don't think it was an average since it was so low - 4.5. I think it was just frozen there because I had frozen the METs display so I could get a feel for the average values. No more than 10 minutes was it below 10.

So the F4 is still reading low and other than increasing the weight value by 50% or so I won't really know what to do until I see a week or two of weight loss and can calculate F4 calorie deficit versus weight lost. If there is a big discrepanciy than I'll either just adjust it when inputting or increase the weight value by the amount needed to give a more accurate result.

I actually think I was burning calories at an 85% of max HR for most of the time on the elliptical. Using the 1-10 exertion scale I really felt I was working at a 7 most of the time, especially after the second interval that I did. The CC Elliptical, Moderate intensity is almost 800 cal/hour! That would be almost twice what the machine showed and three times what the F4 showed!

Looks like I'll just have to wait and see... sigh

well, it looks like you're making progress figuring out the HRM : )

Just keep in mind that because you take Beta blockers its highly likely that your HR will not get up to the age-predicted HR max (probably will max out at about 120?).  That is why the calories burned on your F4 seem so low. 

Aah it feels so good to make your own "scientific" discoveries!!

"Suggestions for further research include changing changing the age on the HRM  This would create a HR range that lies within the capabilities of the individual.  This potentially could create a more accurate caloric expenditure estimation for individuals using heart rate altering medications such as beta blockers."  : )   I was going to post this on Sunday but I got wrapped up in studying for physiology.  Funny to know we were thinking along the same lines!

I will put the LOSER stamp on my head now....

It looks like I'll need a longer time period to really calibrate my F4. Being an old fart I burn fewer calories as it is. Combine that with the beta blockers and other drugs I am on now really skew things. Based on the last weeks results, I'm beginning to believe that the F4 is more accurate than the machines or other calculations I've been making. A one week weight loss comparison to calculated calorie deficit shows a higher calculated calorie deficit using the F4 than what the weight loss indicates. That means I was either entering what I ate incorrectly or that the F4 was actually high in its readings. I think it will take a month of carefully weighing and evaluating everything I eat to get a better calorie deficit comparison.

Kind of frustrating. I bust a butt and still can't get the pounds off. It was easier to lose weight when I was younger. Wish I had kept it off. But 20-20 hind sight is always perfect and one shouldn't "shoulda, woulda, coulda" on ourselves!

Well, I have more data and now firmly believe that my F4 is yielding fewer calories than I am burning. I attribute it to the drugs I am taking that keep my heart rate low for a given exertion effort. I base that on two things, one is that I can feel my bp dropping during a workout and have measured drops of 20 points in systolic and 10 in diastolic pressure - without taking any drugs! That's they way they behave. The second reason is the comparison of predicted versus actual weight loss. Using the month of July to date I compared total calories consumed versus calories burned (I adjusted activity calories by deducting sedentary cal/min since that's in base number) and found it 100% lower than actuals for the last two weeks. I used the last two weeks since they were more controlled and didn't involved travel. Predicted weight loss was 1.2 lbs and actual was 2.8!

That would seem to make sense when I compare my measured burn rates to calculations like the http://www.braydenwm.com/calburn.htm equations, or the calorie king web site calculation, http://www.calorieking.com/tools/exercise_cal ories.php. This morning I did heavy calisthenics for 50 minutes, plus 15 minutes of heavy work on an arc trainer. The F4 yielded 260 cal burned. CC and CalorieKing give ~450 cal. The F4 burn rate/min is a little over 4, the brayden-williams algorithim for an average hr of 89, and age 61 is 11! that is even higher!

So my conclusion is - if yer on the kind of drugs I take you can't trust the calorie burn of an hrm. If used your actual calorie deficit is higher than measured. If not careful it could lead to unintentionally dropping into starvation mode.

The good news for me is that because of my age and lower bmr, as long as I eat 1500 cal/day I am not likely to exceed a 1000 cal/day deficit. That may not be the case for others.

"I have an F6 also.  It gave me readings similar to i_will_lose_it's figures until my trainer set it for me.  I would check your settings.  They may just need to be tweaked a bit."

Any idea on what your trainer tweaked?  I'm waiting for my F6 to arrive in the mail.

The F4 has fewer settings than an F6. Not as much to get wrong. My challenge is the drug regimen I am on. My heart rate response is restricted, even when I exercise, so the F4 doesn't calculate calorie burn accurately for me. It should for "normal" folks.