Elliptical Machine Question - are the calories accurate?

[AgaBoogaBoo]

I do the elliptical machine for 30-60 minutes 4 days a week (Monday through Thursday) and burn 350-700 calories according to the machine depending on the time I spend (all variables being same except time, manual mode)

Is the number of calories it tells me accurate at all? Within 20%? If so, that's great, but it's just hard to believe I'm going through this many.

I've been doing the elliptical and some other things for about a month now, and love it. I find this easier than running simply because I don't have to lift my feet from the surface and have them hit the ground again, not laziness, just personal preference.

Also, is it ok to keep my heart rate around 165-170 when I work out? If I work out at a very high RPM, it can go as high as 200, but I can't maintain it for very long so I don't do that. I am out of shape a bit and so that heart rate might be higher than most.

Cliffs:
1. Are elliptical machines accurate with the calories burned? It seems to use my weight and intensity level to calculate this. When I say accurate, if it's within 20%, I'm happy, just want to be sure these aren't completely off.
2. Is maintaining a heart rate around 165-170 ok when working out? I am on the elliptical for 30 minutes or 60 minutes depending on the day (use some machines the other days) without taking a break.

By the way, this forum has been a lot of help, I've been losing weight and watching what I eat quite a bit more in the past. I've found that working out keeps me motivated to not eat badly because of the effort I'm putting in.

 

[gramboh]

I've read some reports that say they are decently accurate at constant tension/pace, but for things like intervals they are not accurate. It's estimated based on some standard formula for calories burned at a certain weight, so it's not accurate for all people who have diff burn rates.

165-170 is probably fine depending on your age, weight and health. I did some intervals on the elliptical today, 30min of 1min 8mph at 17/20 tension 1min of 5mph at probably 10/20 tension, it said I burned 650 cals including a 4min cooldown after. Seems way high, HR was 180-185 during the sprints and down to probably 160ish at the end of the rest minute, 27 y/o 201lbs male.

 

[RagingBITCH]

What gramboh said - it's based off some formula (hence you putting in your age, weight). It'll never be 100% accurate as you can't take into account metabolism, etc. I'd use it as a general basis/guideline as to how many calories you're burning, give or take a certain %. (Standard of error)