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Is my heart rate monitor even in the ballpark?



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RHOLICKY
SparkPoints: (9,675)
Fitness Minutes: (10,542)
Posts: 42
1/1/13 8:05 P

Wow....that was an awesome answer! Thanks so much for taking the time to write that. It did clear a lot of things up....I am a veterinarian...so very interested in science and physiology...I like details! I know sometimes I let myself get bogged down and details...and if I can't be "perfect", I just give up or use it as an excuse to let myself slide.

That all does make sense, and I know I should focus more on the food. I definitely have noticed when I spend 45 min to 1 hour on the elliptical I will be so hungry I eat way more...and just "un-do" all the good I did.

Just to clarify..when I am doing my intense cardio I shoot for a heart rate of 144-160 based on recommendations of a personal trainer I worked with for a while. I am 38 years old. That should be a good intensity, right? I figure 127 bpm is 70% of max hr of 182 (using the simple 220- my age) forumula.

I am sorry...more questions come to mind. Besides weight loss I am also interested in improving my overall fitness and endurance...specifically for hiking and biking. These are the activities that are part of my motivation to lose weight...I want to keep up with my sister on hikes! To build endurance you have to actually work out longer sometimes, correct? Is it ok to put one longer workout in a week? Like 1 hour once a week? Of course, losing the weight I am carrying will make the hike that much easier to!

Again, thanks so much for your time and thoughtful answers. I really appreciate it!

Sincerely,
Rachael





SP_COACH_DEAN
SparkPoints: (90,332)
Fitness Minutes: (140,313)
Posts: 15,057
1/1/13 7:33 P

Hi, Rachael

I think that 300/hour is pretty low, and that you'll most likely be in the 500-600/hour range. But I can't guarantee that. I'd recommend using the heart rate monitor mainly to do what it does best--tracking your heart rate--and using that info to follow the improvement in your exercise capacity over time. To improve on your cardio vascular fitness/capacity you need to get your heart rate up over 70% of your estimated max, ideally for at least 10 minutes at a time. Working out at 60% will help maintain your current fitness level, but 70% and above really makes your body adapt to the challenge and getter better at what you're doing. That will deliver the best health and fitness benefits, and also increase your calorie burn, whatever it actually is, because you'll have to keep increasing your workload to keep your heart rate in that target zone as your fitness improves.

In terms of weight loss, the good news is that most of that will usually come from a lower calorie intake. Too much exercise is often associated with slower weight loss, possibly because it could increase appetite and/or overall calorie intake, or maybe because it lowers the amount of non-exercise physical activity you might otherwise do. I think that, for many people, the most effective combination seems to be about 30 minutes of fairly high intensity cardio most days, a good strength training program, and as much extra "normal" activity as possible, like walking and just generally trying not to spend long periods sitting still. You'll actually burn more fat during the day, in most cases, when you minimize your sitting time than if you do an extra 20-30 minutes of formal exercise and then don't have as much energy for the rest of the day (or tell yourself you've "already done" your activity for that day).

The main reason this all gets so confusing is that the relationship between heart rate and calorie burning isn't just mathematical, or a matter of physics. There's a lot of biology involved, too, and that's different for every individual. For example, it's true that, if two people walk the exact same path for a mile in the same amount of time, the one who weighs more will be doing more objective, physical work, simply because they are moving more mass. That's the physics part of the equation. But if that heavier person is more fit and adapted to that particular form of exercise, they might actually burn less than the other, less adapted person. That's because their fitness and/or familiarity with the activity means that it presents less of a demand on their cardiovascular system and other body systems. In essence, they don't have do as much biological work as the less fit but lighter person. That will show up in the form of a lower heart rate increase during the activity, even though more objective work is being done.

And that's what causes the problems and inaccuracies involved in trying to estimate energy expenditure based on heart rate, even with a good quality heart rate monitor like a Polar. There is a direct relationship between heart rate and calorie burning during physical activity. For example, if you know what your heart rate is and how many calories you burn per minute at one running speed, and also what both of those numbers are at a different running speed, you could use that info to predict what your calorie burn would be at any other heart rate while running. But that information is only true for you, not anyone else, and only accurate for that particular activity. If you were swimming or biking a mile instead of running, or doing some activity that you're not very used to, your per minute calorie burn could be quite a bit different even if your heart rate was the same.

Obviously, neither heart rate monitors, exercise machines, nor on-line calorie counters have this personal information for each individual or for every activity any one individual might participate in. So they do the next best thing--they use a formula based on average numbers obtained during studies of groups of people doing standard activities like running, walking, biking and swimming. Heart rate monitors will usually be more accurate than the others because at least they do include your own actual heart rate in the calculation. But how close to reality that calorie number will be also depends on how closely you resemble the people in the study that produced the data base used to create the estimating formula, and how closely your activity resembles the activities that were studied. Most of us are going to be significantly different in some way, and these days, many of the exercise options available don't bear all that much resemblance to the basic activities that have been studied extensively.

So, focusing too much on exercise calorie expenditure can be less helpful than focusing on fitness improvement and overall activity level, especially since there's no easy way to know the "real" numbers anyway, unless you do your exercise in a laboratory hooked up to a machine that can actually measure it. Fortunately, tracking food intake carefully doesn't have quite so many complications.

Hope this helps.

Coach Dean



RHOLICKY
SparkPoints: (9,675)
Fitness Minutes: (10,542)
Posts: 42
1/1/13 4:52 P

Hi Dean,

So you don't think that because I do have a very high percentage of body fat I would burn quite that much less calories than more "average" people?

I did just put in a new battery in both the watch and chest strap, and I have all the settings correct for me. It takes my age, weight, height and max heart rate into account....so it probably calculates my BMI? Is that why it reads so low? Because my fat percentage is high and I am just burning less?

This is confusing, because I thought overweight/out of shape people working out at the same intensity as an in shape person actually burnt MORE calories? But it does make sense that the more lean muscle mass...the higher your metablolism. Wow...this is confusing!

So you don't think I actually only burn 300 calories per hour if I am working at a heart rate about 150 the whole time? Because that is what it tries to tell me on a regular basis. I have had it a couple of years and it has always read that low. It would just be nice to have a better estimate....I can use the ballpark that you gave me at least.

I actually have a handle on the exercise...that has always come easier to me than the eating. That is where i need to focus on counting the calories very accurately, it would just be nice to be able to do it with the exercise and I just dont think this monitor is doing it for me! If you know of a model/brand that does a better job with the calorie counting I would love to hear about it!

Thanks
Rachael



SUSANBEAMON
Posts: 2,665
12/25/12 1:46 A

because changing just one number in that estimate of calories used, most places say to just keep it as an estimate. put too much reliance in it could cause you to eat more than you should. of course, estimates of calories eaten is also just an estimate.



MALASIL
Posts: 66
12/24/12 8:36 P

This is good information. Thank you!



SLYSAM
SparkPoints: (37,035)
Fitness Minutes: (90,826)
Posts: 1,450
12/24/12 1:19 P

I would suggest you double check your settings. My polar (a different model) lets you enter your height, weight, age (actually birthdate/year), gender, and also allows you to enter resting heart rate, maximum heart rate and vo2max (it has a built in test to estimate, not sure how accurate it is). I've found changing any of those numbers can effect the calorie burn estimate (maybe not resting heart rate, but I have observed that with all the other listed settings). The main thing is whether your basic stats are correct, since probably do not know the optional stats. It sounds like it is tracking your heart rate from the numbers you list, so perhaps something is off in the formula or numbers it is using to estimate your calorie burn



CORTNEY-LEE
SparkPoints: (50,053)
Fitness Minutes: (42,944)
Posts: 2,982
12/23/12 8:01 P

how long have you had your HRM?

It might need new batteries if you are getting goofy readings



MOTIVATED@LAST
Posts: 13,909
12/23/12 6:13 P

Spark can produce some very distorted figures for heavier people on the elliptical, so I wouldn't put any reliance on the 317 figure.

That said, 81 calories does sound a little low for 15 mins at that heart rate.

I fed those figures into the calculator at www.shapesense.com/fitness-exercise/calcul
ators/heart-rate-based-calorie-burn-ca
lculator.aspx
and came up with 119 calories.

Of course, 15 minutes is a relatively short workout, and is never going to produce a huge number.

M@L



SP_COACH_DEAN
SparkPoints: (90,332)
Fitness Minutes: (140,313)
Posts: 15,057
12/23/12 6:12 P

Hi, R

It sounds to me like both of those numbers could be off by quite a bit, in opposite directions. There are lots of factors that affect your calorie expenditure, and another whole set that affect how accurate any estimate you get from heart rate monitors, exercise machines and on-line calculators might be. As Britomart said, the more closely you resemble the average college student in size and fitness level, and the more closely your exercise activity resembles one of those most studied (walking, running, cycling, swimming), the closer to your personal reality the estimate you get from a machine or on-line estimator is likely to be. Heart rate monitors tend to be more accurate in general, just because they use your heart rate and may include a basic fitness assessment, but they still have problems if your size, general fitness level, and degree of familiarity with the particular exercise you're doing is significantly different from the average. For example, a 300 pound professional weightlifter with a bodyfat percentage of 10% is going to burn a lot more calories on the elliptical machine than a 300 pound person with a bodyfat percentage of 40%, because fat doesn't burn nearly as many calories as muscle. But it's all the same to the program doing the estimates.

It would be very unusual for anyone to burn calories at the rate of 1268 per hour for moderate cardio exercise, and also very unusual for anyone to burn only 324 calories per hour for exercise at the heart rate and resistance/speed levels you mentioned.

You could figure that cardio exercise that gets you breathing and sweating pretty hard for most of your workout, your calorie burn should be in the 600-800 calories/hour range, or 150-200 for 15 minutes (not including warm-up and cool down). Anytime you see an estimate that's quite a bit off from that, you should be suspicious.

So, if you've checked the settings on your hrm and it still gives you that low number, you could use the manual calorie burn feature on your tracker to put in something a little higher, like 150 or so.

Hope this helps.

Coach Dean

Edited by: SP_COACH_DEAN at: 12/23/2012 (18:18)


BRITOMART
Posts: 7,359
12/23/12 1:44 P

I have an earlier polar, so I don't know if this applies to your situation...the default generally is for a fit male person of ~25, 150#. If you haven't programmed it with your own stats, that could be what causes the discrepancy. Generally, hrm's are better than SP calculations, because they measure what you are actually achieving, but they have to be 'introduced' to you first.

Hope that helps...or at least suggests a direction. If nothing works I'd contact Polar, because even at my weight/age/height, I would get more than double what your monitor offers, but I'm older, fatter, and not fit.

Edited by: BRITOMART at: 12/23/2012 (13:49)


RHOLICKY
SparkPoints: (9,675)
Fitness Minutes: (10,542)
Posts: 42
12/23/12 1:34 P

I have a polar ft 7. It has always read low for calories. Depressingly low! I put in my weight and age, and the heart rate works great.

But here is an example: Today I spent 15 minutes on the elliptical. I weigh 300lbs, am 5 foot 5, and am 38 years old. My average heart rate for the 15 minutes was 152, my max was 168. My monitor said I burned 81 calories. I was sweating and working fairly hard for me at a intensity of 5 at a speed of about 5 (mph?).

If I put that into the spark calculator, it says 317 calories. Holy crap! 81 versus 317...That is not a small difference! I think my heart rate monitor should be more accurate, but it is really low. If that seems right, I can accept it, I would just like to get it in the ballpark when figuring out my input and output for calories.



 
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