I agree 100% with the previous answer. I'm in acceptable shape but not great (running 5ks in 26-27 minutes) - my heart rate now, at work, after three cups of coffee today, is 52.
The heart rate cannot go so low that the heart simply stops. It doesn't work that way. Slow heart rate is caused by high vagal activity (the "brake" part of your autonomic nerve system) - but even if those nerves did slow your heart rate down to zero (which is impossible), other parts of the heart not controlled by that nerve system would take over as "pacemakers" and would make your heart rate stay in the 30-40s. This is, of course, completely irrelevant in your case, but just so you know, hearts doesn't stop because the heart rate gets too slow.
And I agree - measuring heart rate is stupid obsessive behaviour. I would encourage every healthy (and anxious) person to sell or throw away heart rate monitors, blood pressure monitors, EKG apps and equipment, pulse ox monitors, everything that monitor the heart, pulse or blood pressure. I've done my share of obsessing about heart rhythm and blood pressure and it doesn't do any good.
I would go back and tell them it has dropped even more. It likely still isn't anything to worry about but since it has dropped just see what they have to say. Do you recall when you had the holter if you had the symptoms of being light headed and short of breath? If not they may not have caught it when it was at its lowest and will tell you all if fine. It's good you had an echo and they didn't see any valve problems but anxiety would likely increase your heart rate not lower it. It is possible your workouts are too much if it is giving you troubling symptoms. Maybe ease up a bit and see if that helps. But go back and ask for a 30 day monitor to try and catch the times when you become short of breath and light headed. It would be good to get that documented and see what is going on. Best of luck. Sometimes these things can take a few times to get properly diagnosed. I will forewarn you though, the treatment for low heart rate is essentially to get a pacemaker so if you need to adjust your lifestyle to help the situation that may be better. If your slow rate is a super bother then you may have to give up hard cardio for a less aggressive form of exercise. Odds are the doctors won't put a pacemaker in though unless you are passing out but just want you to know there really isn't a cure for slow heart rate like there is for someone whose heart rate gets caught in a fast loop. Best of luck getting it sorted and keep us posted on how you are doing.
I'm 48, workout but not at elite level. My resting will be mid 40s, usually in between meals. It's usually higher if I've just eaten.
I never thought much about that. I don't have any symptoms from it. When I need it, the rate goes up normally.
I can remember once using a stupid pulse OX I had just bought. My resting was like 45. I'm thinking, wow, that a low a rate. Then I heard my son fall out of bed. I don't think my feet hit the floor as I jumped up and flew up the stairs to make sure he was OK. not a second thought about that, but when you think about it, that is a healthy heart in action.
The reason I think the pulse OX is stupid? because hyper monitoring your heart rate is a useless and obsessive behaviour. I learned the hard way not to do that. I think HRMs are stupid. Last year I went from out-of-shape to running 5ks in 20 minutes. I did it without monitoring my dumb pulse, and paid attention to stuff I can control.
Anyways, for asymptomatic (no symptoms) low heart rate for someone your age who stays fit, don't worry yourself about it.