polar own cal accuracy?
- Thread starter rockrock513
- Start date
nothing personal, but i don't trust anyone who says "trust me" after a comment like yours. and especially on a forum! LOL!
so if you have the time please share your knowledge with us. i have heard several people say they're inaccuate...but i guess i'm a stickler for data.
thanks, rock
so if you have the time please share your knowledge with us. i have heard several people say they're inaccuate...but i guess i'm a stickler for data.
thanks, rock
Its been a while since I studied physiology, but to get an accurate assessment of how fit you are, you need to be measuring more variables (like oxygen consumption, CO2 output etc.) than just measured HR and perceived effort, and compare that against a standardised measure.rockrock513 said:
So in terms of accuracy, any measure of fitness that relies on guessing from just heart rate is going to be inaccurate. That's not to say its not useful.
Since what it is measuring is going to be done the same way each time, its usefulness is in that you can use it to monitor CHANGES in your fitness.
Improvements in fitness are going to come up as improvements, no matter how you measure them, as long as the yardstick is the same. Likewise for declines.
n
I'm pretty sure it's not accurate but it might not have to be depending on what you're using it for. I record a few things when I train. Using a CS200 to record calories being burned on various set training runs, over time i can clearly see the up and down trends when I've trained hard or eased off. It gives an indication of improvement over time and it also acts as motivator sometimes. For instance if you see your getting close to an all time high on a run it can make you push harder.
Here's how I think my CS200 is overrating the calories I'm burning;
At the moment I'm eating about 1200 to 1500 calories a day(comparing the food I eat with a couple of calorie counters).
My normal rides(almost each day - usually only Fridays off) are telling me I'm burning from 1400 to 2500 calories depending on the rides(from a short 37km hilly ride to 90km less hilly).
Since 19.5.07(or for you in the USA - 05.19.07 !!) until now my weight has gone from(I'm pedantic and weigh myself everyday and chart it) down from 73.4kgs to yesterday(18 days later 06.06.07 or for you in the USA 06.06.07 !!) 70.5Kgs.
If the CS200s calorie counter were really accurate I would've lost a hell of a lot more weight than that!
For example after a 2500 ride I would've burnt off approximately twice what my calorie intake was for that day - two days worth of food taken off from one ride.
I guess I could work it out but we both know that is true.
At the moment I'm eating about 1200 to 1500 calories a day(comparing the food I eat with a couple of calorie counters).
My normal rides(almost each day - usually only Fridays off) are telling me I'm burning from 1400 to 2500 calories depending on the rides(from a short 37km hilly ride to 90km less hilly).
Since 19.5.07(or for you in the USA - 05.19.07 !!) until now my weight has gone from(I'm pedantic and weigh myself everyday and chart it) down from 73.4kgs to yesterday(18 days later 06.06.07 or for you in the USA 06.06.07 !!) 70.5Kgs.
If the CS200s calorie counter were really accurate I would've lost a hell of a lot more weight than that!
For example after a 2500 ride I would've burnt off approximately twice what my calorie intake was for that day - two days worth of food taken off from one ride. I guess I could work it out but we both know that is true.
I thought OwnCal was the Polar 5min fitness test - obiously I am wrong!Bigbananabike said:
I'd question the accuracy of your calorie counters - if you're only getting 1500 kcal in each day, you're only eating enough to sustain a 37.5kg person. Minimum maintenance energy input for a normal healthy person is 40kcal/kg/day (the energy you need for your body to stay alive and perform essential acticities of daily living). I find it hard to believe that you are willfully underfeeding yourself in NZ.
For the days that you're quoting, lets assume you burnt an average of 2000kcal for each day you've ridden, the energy deficit is 500kcal. Now 1g of fat = approx 40kJ = approx 10kcal.
If all the excess energy you'd burnt was fat, that would be 50g that you'd burnt each day, so 18 days = 900g.
Add the energy expended by daily activity that you don't replace:
72 (mean weight of yours between the days) x 40cal/kg / (40kJ/4.18)kcal/g of fat = 300 grams of fat for daily living requirments. So for the 18 days, you've lost 5.4kg by doing what you normally do, which has not been replaced.
So all up, you've theoretically lost 6.3kg for the 18 days. Although there is some variation in how energy is expended throughout exercise (e.g. aerobic vs. anaerobic metabolism), and that we've made a number of assumptions, the numbers clearly don't add up.
That means that either the accuracy of both the Polar meter, or your calorie counters, or both, are in question.
n
If you have too large of a deficit, your body actually stores the remaining fat you have because there will be a false assumption that you are in starvation mode. Your body functions will assume that there won't be any food for it to function so it uses the stored fat as its source. I learned this the hard way when I lowered my calorie intake too low and didn't loose a pound for about 2 months. Once I upped my calorie intake (while keeping a deficit) I started shedding the weight.
==========================================================nerdag said:
Hi.
Thanks for your imput.
Here is what I eat in a typical day;
Breakfast; either vegetable and fish mix with rice or cereal/bran with fresh fruit(kiwifruit or banana)(water on it - not milk).(calories - veges & rice approx 100 calories, cereal and fruit approx 200)
Morning break; muesli bar(840kj, total fat 8.2gms - usually same brand for all muesli bars)(total of the three muesli bars calories = 614)
Lunch; vegetable and fish mix with rice(approx 100 calories)
Bike ride; usually two muesli bars and two sports drinks & one when home for recovery(total of the 3 = 2160kg, 522 calories).
[When I race - most Saturdays in the season(now) I will have 2 or 3 gels and possibly a muesli bar too for a longer race(I don't skimp we racing)]
Dinner; vegetable and fish mix with rice(approx 100 calories)
To find the calories above I've divide the stated calories by 4.1
Calories - veges for breakfast total = 1436
cereal/fruit for breakfast total = 1536
I'm reasonably consistent(boring?!) with my eating.
My CS200 calories used results go from shorter ride 1200 to longer ride 2500.
I think that's way out.
I'm a relief teacher - sometimes I can walk to a school, mostly I have to drive. I'm on my feet a lot in class, sometimes sitting and sometimes on the sports field being reasonably active with kids.
My metabolism is really slow. Although I'm tall and thin(er) my metabolism has always been pretty slow(I eat a lot = it'll stay with me).
I don't want to get into eating more(usually they say protein) in an effort to have "balanced" weight loss as I'm finding what I'm doing is working for me.
We don't eat meat(ok, we have fish) and are moving to a vegan diet.
#When my wife was in her late teens and about to start her nurses training she found she was too fat(her word!!) for the uniforms. She went on a drastic diet of 1000 calories for over 9 months until a few months into her training. She went from a size 18 down to about a 14 and miraculously kept most of it off(with ocasional gains). She's now a 12 top and 10 bottom(after children) and stays that way.
NZers and food = sadly the population has gained an average of 1 pound per year since the 70s. Just like the US there are more and more fast food places etc.
Polynesian people(Auckland where I live, is the biggest Poly city in the world) are often overweight - even with modified BMI etc.
Togan people a new study has found are the fattest people on earth - which must be closely followed by Samoans of whom we have many more of.
Any advice or opinions welcomed.
I'm no dietician, so I don't know how accurate the figures you've quoted are.Bigbananabike said:Any advice or opinions welcomed.
I do know, however, that when you're trying to keep track of somebody's weight (especially if they are very sick), you've got to keep fluid status in mind as well as maintenance energy expenditure, and whatever disease process is going on. Even strictly measuring inouts and outputs, it's difficult to predict somebody's weight without some margin of error.
Unless you're strictly measuring everything that goes in and everything that goes out, there's going to be some disparity somewhere.
n
Compared to the Garmin Edge it is a lot closer. Edge WAY over estimates cals burned because it is based solely on speed. HR isn't even factored in. At least with Polar their formula uses age, weight, and HR. I imagine it is still off quite a bit though. As long as you use the same monitor at least you will have an idea what your burning.
also, did you ever think that you may be packing on some muscle in the process?Bigbananabike said:Here's how I think my CS200 is overrating the calories I'm burning;
At the moment I'm eating about 1200 to 1500 calories a day(comparing the food I eat with a couple of calorie counters).
My normal rides(almost each day - usually only Fridays off) are telling me I'm burning from 1400 to 2500 calories depending on the rides(from a short 37km hilly ride to 90km less hilly).
Since 19.5.07(or for you in the USA - 05.19.07 !!) until now my weight has gone from(I'm pedantic and weigh myself everyday and chart it) down from 73.4kgs to yesterday(18 days later 06.06.07 or for you in the USA 06.06.07 !!) 70.5Kgs.
If the CS200s calorie counter were really accurate I would've lost a hell of a lot more weight than that!
I guess I could work it out but we both know that is true.
============================================================azdroptop said:
You're right - with either there is some consistency and 1 more variable covered with the Polar.
==========================================================impakt said:also, did you ever think that you may be packing on some muscle in the process?
I never "pack" on muscle!
I can get stronger but nothing else.
If the figures were right, that's unlikely. You need to be eating more protein, and a lot more energy than maintenance to do that, since muscle generation is an active process that consumes significant amounts of energy.impakt said:also, did you ever think that you may be packing on some muscle in the process?
n
===========================================================nerdag said:
Hence my post #16.
#15 Didn't seem to notice the low overall rate of calories and the minimal protein.
I'd rather be thinner and healthy(and lighter for cycling) than eat more in the hope (because for some that's all it is) that with weight training etc I could have some muscles that are larger.
My CS200 told me I burned 6650 calories on a recent 101 mile ride; average HR of 154 bpm. I'm 42 and 250lbs.
According to this site:
http://www.active.com/story.cfm?story_id=10767&category=century_challenge&num=0
Aerobic riding burns 0.10-0.14 cals per minutes. So for me 113 kg x 0.13 per minute for 7 hrs, 33 minutes (length of the ride) = 6,654 calories.
If you buy their formula then the Polar is pretty close.
According to this site:
http://www.active.com/story.cfm?story_id=10767&category=century_challenge&num=0
Aerobic riding burns 0.10-0.14 cals per minutes. So for me 113 kg x 0.13 per minute for 7 hrs, 33 minutes (length of the ride) = 6,654 calories.
If you buy their formula then the Polar is pretty close.
That's a bad formula. The standard one is this:Dubbayoo said:
P = (Vg*W*(K1+G) + K2*(Va)^3)/375
Which gives these figures (stolen from wikipedia):
630 calories per hr (174 watt-hrs) for a 200 lb. bike + rider to go 20 mph on the flats
1125 calories per hr (310 watt-hrs) for a 200 lb. bike + rider at 25 mph on the flats
- 585 calories per hr (161 watt-hrs) for a 140 lb. bike + rider to go 20 mph on the flats
- 1070 calories per hr (295 watt-hrs) for a 140 lb. bike + rider at 25 mph on the flats
At 17 - 18 miles/hour you have to count on burning more like 400 - 500 calories. A flat century might only be around 2500.
Anything that tells you that you are burning 1000 calories per hour is either way, way off or you are hauling ass--like a four hour solo century.
All these electronic doodads that give outrageous calorie readings are doing a real diservice to people trying to lose weight. I was talking to a portly fellow on a century last month who told me his Garmin said he had burned 4000 or 5000 cals (I don't remember the exact figure, but it was totally out of line). This was at the 70 mile mark. He did not seem to believe me when I told him that his cal figure was way off. I can easily see him or others pigging out afterward, thinking they earned it and even with the meal they will still have caloric deficit.
