calorie burned - accurate?

[urowgirl]

Hi,
I have been using my new D since the middle of January. Still working on technique and endurance. I can row for about 40 minutes (a TV episode of Alias season 3) and get about 7600 meters. I use a 2 and a half damper with a C Breaze on. (Don't ask about my DF because I have no idea what you are talking about.) My calories burned is around 412. Is this an accurate/reliable number? Just wondering if I can rely on the C2 information.
Thanks

[Bob S.]

Hi,
I have been using my new D since the middle of January. Still working on technique and endurance. I can row for about 40 minutes (a TV episode of Alias season 3) and get about 7600 meters. I use a 2 and a half damper with a C Breaze on. (Don't ask about my DF because I have no idea what you are talking about.) My calories burned is around 412. Is this an accurate/reliable number? Just wondering if I can rely on the C2 information.
Thanks

In my view, it doesn't mean a damn thing. Part of it is real, being based on the actual work (ergs) done. Being an ergometer, that is what it was designed to do and there is a direct ratio of ergs and calories. But the value displayed on the monitor includes a bugger factor that is supposed to account for work that you do other than just blowing air with the wheel. These extra calories have been chosen rather haphazardly and I think that they are unrealistically high.

Bob S.

[Ducatista]

These extra calories have been chosen rather haphazardly and I think that they are unrealistically high.

Depends on your weight and fitness level. As I posted in another thread:

I check Cals on my PM2 at the end of each session, and the value is remarkably close to the number I get from my Polar F4 heart rate monitor, often within 1 or 2%. That's just luck, of course; as my weight and fitness level change, the values should grow further apart.

Interestingly, the PM2 usually gives me a lower value than the HRM in the morning, and a higher value than the HRM in the evening. Apparently the PM2 isn't sophisticated enough to sense just how inefficient my body is before 6am.

Not that the HRM is gospel, either...

[urowgirl]

Thanks for the replies; though both seem to be at odds with each other. The calories burned does seem to be high; but the comparison to the HRM seems to be on an equal parr. I think I will go on the "it does rate them accurate" side because that makes me happier.
Thanks

[c2jonw]

UROW,
This from our website:

A Word About Calories:
Due to the differences in body weight and efficiency, calories on the PM are only an approximation of calories burned by the person rowing. The formula used in the PM2 is as follows:
Calories = (4x ave. watts/1.1639) + 300 cal/hour x time rowed (in hours).
This formula assumes a person of 175 pounds (80 kg.) and a base rate of 300 cal/hour to move your body through the rowing motion at 30 strokes/minute.

And here's a weight conversion formula to get a better approximation of the calories you are burning:

wt-adjusted cal/hr = cal/hr - 300 + (1.714 x weight in lbs.)
(This formula corrects for the effect of moving a heavier or lighter body back and forth on the seat during the rowing motion.)

The only way we know of accurately measuring actual calories burned by a given person during exercise is through Expired Gas Analysis, which is an involved process that utilizes some fairly sophisticated machinery.

Hope this is of help......C2JonW

[Bob S.]

UROW,
This from our website:

A Word About Calories:
Due to the differences in body weight and efficiency, calories on the PM are only an approximation of calories burned by the person rowing. The formula used in the PM2 is as follows:
Calories = (4x ave. watts/1.1639) + 300 cal/hour x time rowed (in hours).
This formula assumes a person of 175 pounds (80 kg.) and a base rate of 300 cal/hour to move your body through the rowing motion at 30 strokes/minute.

And here's a weight conversion formula to get a better approximation of the calories you are burning:

wt-adjusted cal/hr = cal/hr - 300 + (1.714 x weight in lbs.)
(This formula corrects for the effect of moving a heavier or lighter body back and forth on the seat during the rowing motion.)

The only way we know of accurately measuring actual calories burned by a given person during exercise is through Expired Gas Analysis, which is an involved process that utilizes some fairly sophisticated machinery.

Hope this is of help......C2JonW

Jon,

Thanks for contributing this. I had only a vague memory of the details and was to lazy to look them up. I did remember something about the 300 Cal/hr., since there were comments about this being 7200 Cal/day — 4 or 5 times the basal metabolism rate. That's what suggested to me that the formula was too high. But I suppose that 24 hours of accelerating and decelerating 175 pounds back and forth on the rail at a rate of 30 spm might burn that much, especially for someone who has long legs.

Bob S.

[urowgirl]

Jon,
Thanks for the formula. After plugging in my numbers, adjusted calorie burned is about 90 calories less than the PM.

As to the more sophisticated process, I don't think I am up for that, as I am expiring a lot of gas as it is!

Thanks

[c2jonw]

Bob- No problem. Calories burned is an often touted and frequently misunderstood measurement. The 300 cal factor was arrived at by measuring expired gasses (that's breath expirations) of a number of athletes at different paces. Again I'll remind all that the calories burned as indicated on the monitor (and on virtually any fitness machine or HR monitor) is an approximation of actual calories burned by an individual. C2JonW

[michaelb]

what I don't really understand is why the calories burned on the C2 varies by pace; or how that adjustment makes sense. I can see how I burn more calories when I work harder, and so increasing calories by pace that way makes sense to me.

But say we compare two athletes, one rowing what for them is an easy pace at 2:00 and another working as hard as they can but only rowing a 2:30 pace. The person at the 2:00 pace is "burning" a lot more calories according to the PM display even though they may be "working" (relative to each of them, and in part can be measured by HR) much less hard.

Intuitively to me, I would think someone out of shape and working really hard (high HR) may be burning more calories than someone in much better shape who happens to be rowing a faster pace but to them is rowing "easy" with a low HR.

[c2jonw]

Michael,

Intuitively to me, I would think someone out of shape and working really hard (high HR) may be burning more calories than someone in much better shape who happens to be rowing a faster pace but to them is rowing "easy" with a low HR.

Which is fundamentally why a calories burned function on any exercise equipment is going to be an approximation at best. Efficiency varies between people and even for a given person from day to day. Presumably as one gets more fit and more efficient their capacity to work increases and they can burn more calories, but they may have to "work" harder or longer to burn the same calories as when they were fat and out of shape. C2JonW

[jamesg]

So use good technique and get fit. I wonder which is more important.

[iain]

what I don't really understand is why the calories burned on the C2 varies by pace; or how that adjustment makes sense. I can see how I burn more calories when I work harder, and so increasing calories by pace that way makes sense to me.

But say we compare two athletes, one rowing what for them is an easy pace at 2:00 and another working as hard as they can but only rowing a 2:30 pace. The person at the 2:00 pace is "burning" a lot more calories according to the PM display even though they may be "working" (relative to each of them, and in part can be measured by HR) much less hard.

Intuitively to me, I would think someone out of shape and working really hard (high HR) may be burning more calories than someone in much better shape who happens to be rowing a faster pace but to them is rowing "easy" with a low HR.

Clearly someone rowing at a lower rating and HR is indeed using fewer calories. However, the majority of the calories of a competent rower who has more than minimal strength are burned through accelerating the fan. Someone who is stronger has the capacity to burn more calories. Think of it as a car with a larger engine. Similarly, someone who is fitter will be able to maintain that use of energy for longer. Unfortunately perceived effort is not always a good comparison. The good news is that we can all get fitter and burn more calories in the future!

Regards

Iain

[TabbRows]

Eddir Flectcher's Marathon Training Guide avaialbe on his site http://www.fletchersportscience.co.uk uses watts and BMR to calculate a Physical Activity Ratio and then determine the calories expended per training session. His table and formulas are on pages 15 and 16.

But let use my own stats for a run through.

I'm 58, weigh 75kgs(as of last night), so my BMR is 11.5*75+873 = 1,735.
That's how many calories a day I need to stay at 75kgs if I'm just a desk jockey and couch potato. Now let's say I row 2x30 minute sessions at 2:05 pace. That's around 179 watts average. Eddie says the PAR for that pace and wattage is 12.5.

So I divide 1735 by 24 to get my hourly BMR of 72.31. Then I multiply 72.31 by 12.5 to get my caloric expenditure for the hour row. 904 calories. So erging one hour burned 832 calories more than I would have burned if I had simply sat through an hour of Seinfield reruns.

So watts/power output relative to one's basal metabolic rate may be a more reasonable way of determining how many calories you burn.

But IMHO, I think we should be paying less attention to the caloric numbers and more attention to the intensity and duration of our workouts and portion control, sensibility in eating habits. Unless we've planning on pigging out on Ben and Jerry's and want to know how much we have to "suffer" for that pleasurable few minutes, why even try to crunch the numbers?







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[Kate]

If you don't want to have your gasses measured or do a lot of math, you can concentrate on the fact that when you exercise, it speeds up your metabolism for hours. The way I see it, if I work out this morning, I'll still be burning more calories this evening than I would otherwise. Even if the C2 calorie count is low, who cares? It doesn't take into account the extra calories you'll be burning hours from now once you're off the rower.

[iain]

Jon,
Thanks for the formula. After plugging in my numbers, adjusted calorie burned is about 90 calories less than the PM...

I assume that that is an adjustment/hour rowed. If it were for 40mins, I make you 96lbs! If this is the number per hour, you only need to deduct 60/hr from the monitor.

Kate, I agree that you shouldn't obsess with cals burned, but many people find it useful to motivate them as regular long workouts can allow you to lose weight while eating the same you would need to maintain your weight without. So a general appreciation helps. As for the extra cals the rest of the day, I think I read a paper which explained that this effect is only large where the exercise included high intensity, long UT2's don't make much difference after an hour or so, while after exercising flat out it can still be having an effect 37 hours later.