How accurate is a HRM?

[Colby]

  I posted this in another section, but wanted to make sure I got responses from everyone...plus it seems that those who comment under "The Science of Running" seem to know A LOT about it. I use a Garmin 305 with heart rate monitor and this morning on a run where I picked up the pace for about 3 miles in the middle of the run I hit a 205 BPM. I am not sure exactly where on the run it happened, but it showed that as my max for the run when I went back on the Garmin to check it out. I am not trying to be a heart rate runner, but I am just curious how accurate these things are. I am a 26 year old male and even according to all the formulas I should be somewhere below the 200 BPM range. I have never actually checked my max heart rate, so I have no idea. My question is really how accurate these things are and if 205 could be close to what my max is?

[Mike Davis]

I get very consistent results with my Garmin 305 and they are right in line with what the machines at the YMCA tell me with the built in HRM hand grips or my Polar chest strap. I think my true max is also 205 although I haven't seen over 195 in a long time.

[Eric Day]

True Max HR is different from person to person. The only way to measure this is through a medical test where they do all kind of test on you while you run on a treadmill and measure tons of stuff.
The formula of 220-age, is just a round figure. You should never measure based on this, but it is a starting point.
About accuracy of the Garmin, they are quite accurate, just as long as the belt is placed properly and has not moved. I also had a HR of about 225 once, but knew it was a fluke (was I having a heart attack in the middle of my run?).

[Colby]

I know that the standard 220-your age  is pretty suspect, but I figured it was a place to start. 205 BPM just seems awfully high for someone my age.

[Kam]

I would be very surprised if that was a correct reading.  Keep using the thing, and see if the number crops up again.