Based on my experience, max heart rate has been decreasing with age. Back in my 50's I could max out over 200 bpm any time I was putting out an extreme effort.

Now, in my 60's (67) my full on max is in the 175 range. After my fake heart attack my cardiologist told me that 165 should be my max, plus my GP put me on statins so that may be holding my heart back a bit too (but I don't know this to be a fact).

So for me, yes, my max has decreased with age though there may be additional factors too.

Rick / OCRR