I know the dogma about HR diminishing with age doesn't hold for everybody, but have any of you experienced a MHR that has increased with age?

My measure of MHR is admittedly unscientific - it's really just the HR I've noted during repeated maximal efforts.

I discovered cycling when I was 49 (I'm 56 now), and though I had no HRM on my bike, in the winter I rode a stationary recumbent bike in the gym and on that I found that the MHR I would see was 175 BPM. Repeatedly over the course of my first two winters, when I did repeated hard intervals, I would get up to 175 BPM, and never one BPM higher I figured that my MHR had to be close to that.

About 2 years into my life as a cyclist, I got a HRM for my Garmin. The highest HR I saw in those days, getting dropped while climbing hills with people younger and stronger than me was 178 BPM. Again, I saw that number repeatedly over a period of maybe 2 years, when I was at my apparent limit, but never saw anything 1 BPM greater. I figured that my MHR was maybe a little above that limit, and that the difference between that value and the value I saw in the gym was a difference in the measurement devices or that I pushed myself a little harder on a real bike.

A couple of years later, that value crept up to 180. Again, it's a value I saw repeatedly over a period of time, but not higher.

Last year, for the first time, I saw values above 180. Not very much, but on several occasions I saw up to 183.

Today, on a ride with some younger people, pulling at 25 MPH for a stretch, it seems I hit 185 BPM. I am surprised by this, because I was definitely working hard, but didn't have that awful feeling that sometimes accompanies maxing out.

So - unscientific measurement practices and my MHR has always been the same or even decreasing? Instrumental drift? Or is my MHR increasing?