So THAT'S 650 Calories of cardio. Jeez. I haven't had much luck tuning my Polar F55, so I did my elliptical work yesterday afternoon using the calculated burn amounts based on steps per minute, weight and difficulty level.

Longer ... and Much More Difficult
Kind of interesting - I was on the machine for 53 minutes instead of my usual forty something. According to my watch, I burned 775 calories, but the calculations (and the elliptical machine, by the way) said I burned 650. As best I can tell, my watch calories are as many as 150 calories off in a 45 minute workout. That makes a HUGE difference when calculated over the course of a week.

It means that instead of a 22% calorie deficit, I've probably been at something closer to 10% on average... which would explain the shallow weight loss curve.

Getting the F55 On Track
I really have to find a way to "dial my watch in". If my BMR were off, I could make a simple adjustment to compensate, but when you have a tool for measuring calorie expenditure that is returning a (very) optimistic burn rate, the error is exponential.

I did some research on the internet and learned that the F55 calculates calories burned by using the VO2 Max (oxygen consumption) measurement. I haven't set the VO2Max on the watch, so little wonder it is way off!

Estimating VO2 Max
Usually a VO2 test involves running as hard and as fast as you can for a certain duration. The documentation for the watch says it can estimate VO2 without exertion, but I think I want to crossreference its results with more traditional tests.

I found a page with info and links to several different tests that look promising.

http://www.brianmac.co.uk/vo2max.htm

Polar F55
Here is the watch I'm using, by the way


The calorie drift I'm complaining about is a configuration problem on my part. All in all I'd say it is a fantastic investment if for no other reason than the new comfortable heart strap Polar has developed.

If you have used Polar watches in the past, you are probably familiar with this old style large plastic strap.

Old Polar Strap


The early versions of this strap used very rigid plastic. If you cinched it tight, it would slide down as you ran causing incorrect readings. If you kept the strap loose, it would bounce causing incorrect readings. There didn't seem to be any middle ground. Newer versions of this design used more flexible plastic, which helped, but not much.

The newer Polar strap is made of flexible material that holds really well. You just wet the contact pads with tap water before wearing and you've got a reliable monitor! I'm REALLY impressed with it.

New Polar Strap - with unique ID


I have yet to see this strap slide, move or bounce. The heartbeat readings are very regular, and the strap is extremely comfortable.

Another problem that this version resolved was that of too many polars in the area. When my wife and I would run beside each other, my older heart strap would often interfere with her monitor. The new version of the strap and watch use special encoding (called "Wearlink" so the watch knows to only pay attention to my strap, not others. (You can still use polar enabled gym equipment )


More Later!
B