I've seen the same thing. I'm a middle aged guy, endurance athlete, was competitive nationally at the NCAA level way-back-when. I learned a lot about nutritio

I've seen the same thing. I'm a middle aged guy, endurance athlete, was competitive nationally at the NCAA level way-back-when. I learned a lot about nutrition and physiology as part of my sport. Back then the conventional wisdom (not universally accepted) was that max heart rate was "220 minus age". Well, if you do that math on me, the peak -- not sustained -- rate that I reach now is outrageous, in a good way. Granted, I've learned to push through and perform at high levels of exertion and exhaustion, it didn't happen from one day to the next. Anyway, there were times ~3 years ago where I'd be tearing up a workout, Fitbit would read 130, I knew it was f*Ing wrong. Bought a chest strap and saw what was really going on. Low 190s. Thanks FitBit!! I would have been happier if the FitBit just put up "??? WHAT THE HELL ARE YOU DOING OLD MAN???"