Calories Burnt During Exercise...help!

happy_jax

Hi all,

I have always felt pretty confident that I am accurate with my calories burnt during exercise as I am pretty religious when I comes to wearing my heart rate monitor! I've had my Polar F11 two years now and love keeping tabs on myself!! ...sometimes even wear it washing the car, mowing the lawn etc just to get a better estimate of calories expended, which I know is pretty sad! :blushing:

However, I've noticed recently other people seem to burn a lot less doing things I do... started to make me worry if there was something wrong.

I know I have a very high maximum heart rate...I have super low blood pressure and used to pass out all the time so am on lots of different medication which does various things, including raising my heart rate - so for example, when I'm at the gym just on the cross trainer my heart rate is usually between 170 and 185. So could this be one of the reasons why? And if so, would this still mean I burn more calories or would it give an inaccurate reading? Also when I run (which I hate) my heart rate can reach 205 which should be technically impossible given the 220 - your age (I'm 24) rule...?

I do push myself hard and love to exercise, so don't cut any corners, so perhaps I do naturally burn a little more anyway, but some of the differences in what other people have burnt and what I burn seem too extreme to ignore...unless of course other people guess...and under-estimate to be on the safe side??

I have tried to ask my GP about this recently, but as I'm sure is the case with a lot of GPs, as soon as you mention weight he thinks I am whinging about nothing. As long as I am not unconscious he seems to be happy!! :laugh: But if I am entering into MFP I burnt 1050 calories in 70 minutes at the gym...then happily munching through at least 75% of these 'extra workout calories' then maybe this is why I'm making such slow weight loss progress?

Sorry for such a long and confused/rambling message! I'm just a little concerned....

Please do let me know if anyone has any ideas...or even what you do and what you burn on a typical workout?!

Thanks!!

muppetkeeper

Hi,

I think you are doing the right thing. Eat 75% of the calories you burn, and if you don't lose weight, reduce that slowly to say 65%, and trim to what you know is right for you.

Personally I know walking, even quickly, isn't difficult for me, so I halve those calories, but running is, so I keep all of them!

MK

lisajuly

I am another person that has a freakishly high heart rate, especially when i'm running. I'm 41, and i've seen my hrm go up to 216. (yes, that is not a typo). I know when i'm running, if i see my rate between 180-185, i have to dial it back a bit, but i can run comfortable with my hr around 170.

back in 2005, after i ran my 2nd half marathon, i finally had gotten a garmin that came with a hrm. I nearly gave myself a nervous breakdown during my first run with it, because it was showing my heart rate up around 170. i spoke to my doctor and he checked me out and guess what, i just have a freakishly high heart rate. he told me that w/o getting tested (which i eventually did) a good guide to use was that after 1 minute after stopping running, my heart rate should have dropped at least 10 beats per minute (bpm) and that after 2 minutes it should have dropped 30 bpm. if I was doing that, he wasn't really concerned.

That being said, I'm not giving medical advice. you could get a VO2 max test done to determine your maximum heart rate and then determine your zones from there. (some colleges/universities do this kind of testing). Once you know what your hr max is, you can determine your zones from that. There are some people that the "220-age, then take a percentage" formula does not work for. You could be one of them, I definitely am. You can also request a stress test from your dr. if you believe there is something wrong.

Another way to determine your max HR is to run up a hill (pardon the expression) balls out. check your hr. walk back down the hill. Repeat several times. After 5-6 times, average the high heart rate you get, and that will be pretty close to your max HR. you can then determine your zones from that.

Lisa
PS. i burn approximately 125-130 cals for every mile I run, which is a bit higher than most people. they say the average is @100, but even when i'm at goal weight, i still burn around 122-125.

PureAndHealthy

Is it safe to have a heart rate that high? That sounds a little scary to me. But my medical knowledge is limited... I guess I'd probably check with a doctor to make sure my heart wouldn't explode! lol :embarassed:

Azdak

Assuming there is no underlying medical problem (the "freakish HR comment covers that), there is a high probability that your higher HR is causing your F11 to overestimate your exercise caloric burn.

HRM calorie counts are based on the relationship between heart rate and oxygen uptake (VO2). For example, 70% of max HR equals approx 57% of VO2max. The HRM estimates your VO2 max and it estimates your HR max. If you are working at a certain heart rate, it assumes you are at "X%" of your HR max which corresponds to "Y%" of VO2max. From that extrapolation, it estimates your VO2 for the activity and from that calculates your caloric expenditure.

Example: your VO2 max is 42/ml/kg per minute. Your are working at 70% of HRmax, which translates to about 57% of VO2 max. Your actual exercise intensity is estimated at 24 ml/kg/min (57% of 42). From there, estimating calories is pretty straightforward.

The F11 allows you to manually input both HRmax and VO2max, if you know these numbers. If you don't, it estimates them based on the usual equations (it uses its own proprietary software to estimate VO2max based on the "fitness test" program, if you take the test; otherwise it picks a number--I don't know on what basis).

In your case, or anyone with a high HR, you can see the problem. If your normal HR response to exercise is higher than "average", the Polar now assumes you are working at 90%, 100%, whatever, of your HR max. So--back to our example--instead of calculating calories based on 24 ml/kg/min, it might be assuming you are at 35-40 ml/kg/min, which would make for a substantial overestimation.

Undergoing testing to determine true HR max and VO2max can be expensive and uncomfortable (not to mention that many recreational exercisers cannot push themselves to 100% effort). The best thing to do, if you know your heart rate goes up that high, is just adjust the HR max in your HRM setup. Try putting it up to 220 and see what happens.

Because it would be extremely difficult at your weight to burn 1000+ calories in 70 min. If you are running at 6 mph, for example, at your weight, your calorie burn would be 700 Calories/hour. You can use that as a rough benchmark to try and "calibrate" your HRM.