Is my heart rate monitor broken? Did I really burn 3300 calories?

Factual Questions
1

I got this nifty gift for Christmas, the Nike C6 Heart Rate Monitor.

I am first alarmed that doing anything other than sitting on my couch and playing video games causes my heart rate to spike to the low 100s. That seems awfully fast. Sitting on the couch and playing video games brings my heart rate down to 72 (the one at the supermarket says 60, but arguably my arms are bigger than the largest suggested size for the cuff.)

I go to this “boot camp” style work out class (heavy calisthenics, but with the inclusion of weights), anerobic and I have an unofficial calorie expenditure of 586 calories for the hour. It’s unofficial b/c I didn’t know the calorie counter thing was on.

The next day, I read the manual and set it at the start of my “spin extreme” class. I am a little disappointed that I burn only 1116 calories for the hour :eek: ! I show this to one of the personal trainers and while equally shocked, they are also equally impressed by this. From their reactions, it apperas that this is not out of ordinary.

For the next 5 hours, I drive home, change, make dinner, watch USC stomp on OU, and win $64 playing poker on-line. I forgot that my heart rate monitor was still going (I was betting on OU and wanted to see how my heart rate changed throught the game, it didn’t really, hovering around 97-101). Playing poker brought my heart rate down to ~92. I check the calorie counter, and I have then burned 3364 calories when I took it off 5.5 hours later.

Is this right? Can I really be burning this many calories? While not fat, I’m not exactly cut either? Is my HRM broken?

2

If the monitor is right, you won’t be ‘not fat but not exactly cut’ for long. If the monitor is right, you’re achieving infomercial-quality calorie burning, and will lose around 4 or 5 pounds per day.

But it’s probably not right. It’s possible that the figure you got is somewhat larger than what you’d get just by adding up calories burned in deliberate exercise, because it seems to include your base metabolism by measuring your heart rate at rest. Still, it’s unrealistically high. The algorithm it uses to calculate calories burned from heart rate may be incorrect, or it may be measuring your heart rate incorrectly. Try checking your heart rate manually and see how it compares.

Are you sure it wasn’t set to kilojoules? 1116 kJ (266.6 Calories) is less than an hour of spinning is supposed to be, but 3364 kJ (803.5 Calories) seems like a realistic figure for 5.5 hours.

3

A marathon only takes about 6000 or so calories, so it seems pretty unlikely.

4

These values seem reasonable to me. When I do an orthostatic test (using a Polar 625x), I have a initial resting value of c.40, a peak on standing of c.85, and a static-standing value of c.50. This pattern agrees with the pattern you found reasonably well.

In order: No. No. I have no idea. No

The calorie expenditure formula is just a heuristic, it might be correct for you, or it might not - in your case the resting expenditure is ridiculous, so it’s wrong! The exercise-related values are more plausible, but still too high, IMO; don’t know how ‘extreme’ your spin class is, but I would be surprised if you actually expended >700kcal/hour. One problem with your resting kcal value is that I doubt the formula used by the gadget is really designed for measuring resting expenditure.

When running, it’s quite possible to expend 1000kcal/hour. I imagine you could also achieve this on an ergo. Unlikely on a bike though.

Re. ultrafilter: 6000kcal for a marathon is absurdly high. 3000 is more in the ballpark. 100kcal/mile is the usual rule of big toe, and this varies little according to running speed.

5

Sounds off to me. I used to exercise with a heart rate monitor all the time until it broke, and my results were very different than yours. Easy exercise (walking, etc.) was about 400 cals/hour, hard exercise (biking, spin classes) were more like 600 cals/hour. Just wearing the thing all day while I sat at the computer was hardly anything - like 350 calories for the day. I assume the monitor only measure exertion, so basic body functions like digestion and breathing don’t show up on it.

My WAG is that as you wore it, the watch lost contact with the transmitter and it went haywire. I remember mine would do that. The chest transmitter relies on sweat or water to keep it in contact with your skin; when you just wear it without exercising (and thus, not sweating), it loses contact pretty easily. When that happened, the watch part of it sometimes started recording abnormally high heart rates - like 200 or 300 beats a minute. If yours did the same, that may be the reason you recorded such a high calorie expendature.

For the record, I had a Polar heart rate monitor.

6

My avg heart rate was ~158, because the instructor was a speed maniac that day. I can mostly keep pace with her, but I forget that she teaches another clas right before this one. She did put it some ultra heavy cycles, but it was mostly speed. My high rate was 182, and my low was 136 (mostly between sets). When I showed her my rate, she was impressed and not too shocked. She said that guys burn more calories for the same amount of work.

When I was marathon training, I remember in the winter doing 1.5 hour runs on the treadmill (ugh - long sluggish runs for maintenance). Of course, I was 5 years younger and 30 pounds lighter (though not nearly as strong as I am now). I think my highest caloric expenditure was around 1400. I’ll have to dig up my old logs if I haven’t thrown then away already.

Should I return my HRM? It seems defective. I want an accurate calorie counter!

7

Well, your HR values are sensible.

Your heart rate values seem fine, so the HRM is almost certainly fine. It may be that the equation used by the watch to calculate calories does not work for you - I think these equations can be off by tens of % for a given individual. Or Athena’s explanation is also quite possible. Also, did you input your personal biodata (i.e., sex, weight, etc.)?

8

Yep, it’s all in there. I had my boot camp class yesterday and for 1:12:45 I burned 1256 cals. This workout was highlighted by wind sprints (ladders) and about 200 push-up type movements. ~147 avg heartbeat. Then I ran for 15 mins at a shuffle pace (14 min mile).

9

Not quite. One pound of body fat is equivalent to 3500 calories.

Hey look, I even have a site:

http://www.annecollins.com/calories-weight-loss.htm

At this rate, you would be lucky to lose a pound a day, and that would be if you pretty much didn’t eat anything.

Look at it this way, your average adult burns 2000 calories a day. Add an hour long cycle class for an additional 1000 calories, and I could totally see you burning 3000-4000 in the day, depending on what else you do.

I run marathons and I run at a rate of 1200 calories and hour, so on a day I run 20 miles (in about 3.5 hours) I burn about 2700 running + 2000 for normal daily activities, for a total of about 4700 calories.

10

Oh and one more note. I very carfully watch what I eat and for periods of weeks I have kept track of every calorie I have eaten. I did this in an effort to find out how many calories I need to maintain weight. By doing this, I found that the figure of 1200 calories an hour for intense excercise (running for me) was pretty acurate, but this is obviously going to depend on your weight, age, experience and such. I also verified that ~3500 calories deficit led to one pound lost weight, and FYI I burn about 2250 calories in normal day to day activities.

11

I think you’ve slightly misread the OP’s posting. He allegedly burned ~3500kcal in 5.5 hours of doing nothing. At this rate, he’d be burning c. 15,000kcal/day, before you add in any actual activities! The guy would be practically glowing with metabolic loveliness.

And thus you see the problem with the OP’s derived values!

Another possibility for the OP, to check Athena’s suggestion: Download your 5.5hours of heart rate values from when you were doing nothing much, and see if they include lots of spurious high readings.

12

Counting calories by heartrate would not be very accurate. It would be like trying to calculate gas consumption of your car by the RPMs. If you’re in neutral and rev the car to 5000 RPM’s, you’re using less gas than if you’re driving up a hill at 5000 RPM’s. For example, if your heartrate goes to 150 because you drank a cup of coffee, you’re not burning the same number of calories as if you were riding a bike to get your heartrate to 150.

Most people who are very athletic have low resting heartrates. It could be that the watch is tuned for those people.

I think the best use of the heartrate calorie meters is as a guage of how hard you are working out. So if you burn 600 calories in one session and then 800 calories in the next, you can say that you worked out 30% harder. However, I don’t know that you can say you actually burned 800 calories. The watch doesn’t know if had a higher heartrate because you were really spinning that much faster or because you were focused on the attractive person in front of you.

13

Well, I’m sitting around in my office and after 1:40:39, I have burned 308 calories. My heart rate does fluctuate from as 68 to 85.

In the last 1:40 I have had a heated negotiation with one of my clients, I had to go open and close the door a couple of times, and I went downstairs to get some coffee. As I type this now, I’m at ~73 bpm (+/- 2).

I ran yesterday for 30 mins (at a slow pace ~14/min mi - to burn these last few percentage points of fat), and the machine said I burned 336 cals, while my HRM says I burned 691 (iirc, I erased the data before making note of it). The personal trainer/manager said that more muscular people will burn more calories than non-muscular people, even if the same weight.

Perhaps, my calorie counter is correct?

14

That rate of calorie consumption still seems implausibly high, unless you are a very big chap, with arms like barrage balloons (you’re looking at 4500kcal/day just sitting around, based on that sample).

Again, I would not trust a value of almost 700kcal for less than 3 miles of running. The treadmill value is more plausible.

Note that unless the HRM asks you how muscular you are, this will not be contributing to its energy expenditure calculation. So, if you are built like Mr Concrete, I would expect the HRM to underestimate your calorie use, rather than overestimate it.

I’m sure that your HRM is working as it was designed to. I would be wary of trusting the calorie values though. Had a bit of a trawl thru’ some Sport Sci literature, and from Schutz et al. (2001) [Obesity Res 9: 368-379], we have:

“HR is not a good predictor of EE at low levels of physical activity (Livingstone 1997, Br J Nutr 78: 869-871)”.

and

“Perhaps the major limitation of assessing physical activity based on HR data is the lack of established relationships between HR and energy cost of the wide variety of activities encountered in daily living.”

The calorie calculator’s heuristic is almost certainly tuned for standard exercises. Basically, I would forget about using the HRM to measure resting energy expenditure and I would be a little cynical about the values you are getting during exercise.

You could try to find out what equation the HRM uses. Or, as a matter of interest, you could borrow another model of HRM and see if it gives you comparable values to your Nike confection.

Or you could just fling the thing out a the nearest window, and have a doughnut instead (my choice of choice).