I use a HRM and am 68 with a minor heart condition. I will look at the results after a ride on map my ride. My heart Dr said that the medication I was taking regulated the heart rate more than the activity level so I tend to get some strange results sometimes. overall I think it is a good tool but I would not obsess over the numbers. I am using the MIO Fuse and if it is withing a few beats that is good enough for me. With the cheaper chest strap/watch units I had problems with them reading at all even using the gel etc.