Unfortunately with me me that would be a problem. I have high blood pressure and am on medication (Toprol) to control it. So unfortunately also controls heart rate very well. It is a real bummer at the gym, when I test my heart rate on those pad thingies and eventhough I am working pretty hard, my heart rate doesn't rise very much...only a point or two at the most.
I hope it works for others though! Its a good idea!