How many kcal burned during a workout?

[Pharm_Fed]

So I have been using my Polar heart rate monitor for months now and I'm curious as to how accurate these things are. Under set up it asks for me age, gender, height and weight. I assume there is a formula that uses those inputs with my heart rate to calculate kcal burned over a period of time.

During a typical 1-hour workout, not including cardio, my average heart rate is usually around 145 or so, and I burn around 800-900 kcal. This seems like a lot to me. Then when I do 20 minutes of low intensity cardio, keeping my heart rate around 135-140 I burn another 250-300 calories. With lifting + cardio it's not unusual for me to burn 1200 calories at the gym according to my watch. Does that sound right to you guys?

A while ago I wore it for an entire day and over 24 hours it said I burned close to 4000 calories. This also raises suspicion because I was gaining weight steadily and was eating only 4500-4600 calories a day. Also, now I'm only eating a measly 2800-2900 calories a day trying to lean up and it's not happening very quickly. If my body burns through nearly 4000 a day, I would think the fat would just fall off.

Opinions?

 

[Get_Swole]

I think its probably a little high. I think most heavy weight training sessions fall around 500 or 600 cals' i could most certainly be wrong though. Burning 1000 cals in a weight training session just doesnt really add up. LIke you said my cals are a little even lower then yours and i should be shrinking like a cotton shirt in the dryer if im burning that many calories.

also remember to take it slowly 1.5 to 2 ilbs a week is plenty.

 

[cinsam]

This is my understanding of kcal's and how they are burned and calculated. A kcal is simply a unit measure of energy so every time your body does any activity you burn a certain amount of them. The amount burned can vary greatly depending on the intensity, length of workout, type of activity and especially your weight and muscle mass. <?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>
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If you have a good way to measure your activity such as the Polar unit they are typically pretty accurate. The only thing you are missing is type of activity. Weight lifting will burn fewer calories than say running or cycling will.
I am an avid Triathlete so calories and weight are always being monitored. I have a Garmin GPS that you enter weight, age, height, gender AND activity such as running. It tracks your heart rate, distance and so on. I typically burn up to 1000 kcal per hour and even more during an event at race pace.
Most weight lifters have not only a higher overall weight but an increased muscle mass that contributes to more kcal burned during activity. For instance one of my teammates is only 160lbs so he burns typically 30-40% less kcal to cover the same distance as I do and my wife (110 lbs) even less simply because it takes their bodies less energy (not effort) to do the same amount of work.
There is a pretty good website www.caloriesperhour.com that has nearly every activity you can imagine and it is fairly accurate at determining your expected kcal expenditure based on the info you enter.
Hope this helps!