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Re: [RC] accuracy of hand helt heart rate monitors - Truman Prevatt

One final comment on accuracy. They are extremely accurate. The pulses are received by the watch. The watch uses a crystal time standard (quartz) to calculate the time between beats and then uses that the calculate the heart rate. The accuracy is as good as that of the quartz crystal - which is quite accurate (much more than a human watching a watch).

It's not the accuracy that is the question but the artifacts generated.

Truman

Truman Prevatt wrote:

When it is showing a "double beat" it is actually all the beats - if you listen closely in a stethoscope you will hear the four parts of the beat. The HRM is designed to only count two - on the assumption that the current flow from the other two parts of the beat are too small to be detected by the sensors. This is true in humans and these units are modified from those designed for humans. If the current flow associated with all four parts of the bear are strong enough to trigger the sensor - you get double the heart rate.

I've taken a lot of pulses at rides and have seen it a couple of times. Interestingly enough it has always been on non-Arabs, both Morgans and walking horses. One time a walking horse comes in. He was calm, alert looked in great shape but his heart rate read 110 off the monitor. I put a stethoscope on him and the 110 had to be 55 since by the time I got a count on the stethoscope it was 52.

My old walking horse mare had a strong heart beat and my monitor would pick up all four parts of the beat.
You can usually eliminate this with your own monitor by placement of the electrodes or changing the polarity of the connection of the electrodes to the transmitter. The transmitters have a positive (red) side and an ground (black side). The connectors one the transmitter normally reflect this. Sometimes by reversing the which electrode goes to which connectors will solve the problem.


With my mare I solved it by switching the girth electrode to her right side and the under saddle electrode to the left side (opposite of the recommended position). That solved the problem. If I rode with both electrodes under the saddle it also solved it.

More horses - but not many - have the opposite problem. The hand helds can't detect the heart beat. That can be an issue more it seems on slab sided horses. You can normally solve that by holding the hand held monitor lower than you normally would. I've won quite a few bets when people walk into the box, I put it on and they start tell me you have to use a stethoscope on this horse, yadyad......... By the time the third yada comes out - I have the pulse, call their number and send them on :-) .

Truman





--

"A mathematician is a device for turning coffee into theorems."

- Paul Erdos (1913-1996)




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Replies
[RC] accuracy of hand helt heart rate monitors, LAWRENCEC BENNASCONI
Re: [RC] accuracy of hand helt heart rate monitors, Truman Prevatt