When I do my HIIT routine, I wear a heart rate monitor with a calorie counter. I programmed the watch with my weight, age, and sex. My heart is monitored with a chest strap.
How accurate is this thing? The reason I ask is that the treadmill (which links wirelessly to my chest strap, and asks only my weight) reads out 488 calories…the watch (that came with the chest strap) reads out 838 calories.
Any ideas?
HRM is better then the treadmill but neither are really giving you a true picture because the beauty of HIIT is in the afterburn.
833 sounds really high for a short HIIT session, and if its not short then its not HIIT. Unless of course you are 300lbs then I’m an ass.
[quote]pushpulljunkie wrote:
HRM is better then the treadmill but neither are really giving you a true picture because the beauty of HIIT is in the afterburn.
833 sounds really high for a short HIIT session, and if its not short then its not HIIT. Unless of course you are 300lbs then I’m an ass.[/quote]
Actually, I’m a semi-soft 250lbs. The example I gave you was of a test run of the new HRM. And yes, I mispoke. The test run I did was 30mins of hard cardio at 85% of my max.
I would say the watch would not be too accurate. It may be useful to compare one workout with another. For instance if the watch estimates 800 calories for one workout and 300 calories for another, it is probably safe to assume you burned a lot more calories in the 800 calorie workout. In other words it is probably a fairly good indicator in comparing yourself to yourself.
When it comes to the exact calories it would be really hard to estimate based on just age, weight, and heart rate. There are a lot of variables that vary from each individual. If you took 2 people (one a 220 pound 35 year old couch potato and the other a 220 pound 35 year old NFL quarterback) I can pretty much guarentee they will be burning different calories at the same heart rate. Even with the same age, weight, and heart rate it would not be comparing apples with apples.
Using heart rate in the formula also throws things off. Each person’s heart has a different stroke volume. That is the amount of blood the heart pumps with each stroke. Each person also has a different maximum heart rate. When oxygen demands (whether from aerobic exercise or by the oxygen debt created by anaerobic exercise) is high, the heart has to pump more blood. One person’s heart may speed up significantly. Another person’s may speed up less but squeeze more forcefully. I have heard the analogy that some people have a Yamaha heart. Like a motorcycle engine it revs high to meet increasing demands. Some people have a diesel heart. It does not rev high, but still creates enough power to meet demands. You could easily have two athletes of the same age and weight. One may have a maximum heart rate of 220; the other may have a maximum of 170. The watch would estimate both as burning the same calories at a heart rate of 160, but the guy with the higher maximum heart rate would probably be burning a lot less calories. The guy with the lower maximum heart rate could easily be working a lot harder and burning a lot more calories. His heart has a much higher stroke volume to compensate for the lower maximum heart rate.
For these reasons I would say the estimates are not accurate, but are useful as a point of comparison between one workout and the next. I personally have been on workout equipment where I have hit around 2000 estimated calories in 40 minutes. If those estimates were accurate, I could get down to 1/2% bodyfat in about 2 weeks!
I don’t think any calorie counter can be accurate since your metabolism depends on genetics, muscle mass, conditioning, and a host of other variables that you can’t enter in to your heart rate monitor. The company that made your heart rate monitor probably tested groups of men and women in certain age groups to come up with average calorie expenditures for sex/weight/heart-rate.