Cycling UK Forum

I used to get similar spikes, with the same maximum heart rate, with my Polar HR monitor, but realised they were under power cables and at a couple of other particular locations with no obvious sign of high voltage cables. I didn't have any physical sense of a high heart rate and it came down to normal very rapidly. For various reasons I changed to Garmin HR monitors 7 years ago and, having used 3 different Garmins, I haven't had any problems with my heart rate since then! Obviously, don't ignore medical advice, but it might not be your heart that is the problem.