I am healthy, 37 years old, and have always been an athlete (competitive swimmer growing up, have run several marathons, etc.). I was diagnosed with attention deficit disorder
3+ years ago and in the last 6 months, I notice a huge fluctuation in my heart rate when running. It seems to "get stuck" at about 84 beats per minute and then "stuck" over 190. For each, if I stop running, it jolts my heart back to normal pretty quickly.