Last week I was testing my resting heart rate, and it was well under 50. Now, this week while viewing my resting heart rate it has been barely under 60? Any possible reasons why? Thanks.
Last week I was testing my resting heart rate, and it was well under 50. Now, this week while viewing my resting heart rate it has been barely under 60? Any possible reasons why? Thanks.
Bump.
Still recovering from training?
Poor sleep?
Stressed by something else?
Not as relaxed when taking it this time?
Caffeine, etc?
It will often vary by several beats for me on any given morning due to any of the above factors. Recovery, sleep, and stress can definitely explain a 10-point difference for me.
I know its fun to be scientific about these things, but honestly this means very little about fitness.
The heart, if one were to take it out of your chest, would beat on its own. If a healthy heart, it would beat at the rate of the atrial pacemaker cells, the Sinoatrial or SA node, at about 100 beats per minute.
As you gain fitness, the heart muscle increases in size and pumps with stronger force (or stroke volume, the volume pumped with each beat). the pressure sensors in your blood vessels (aorta and carotids) sense the increased pressure, send a signal to your brainstem saying there is a ton of pressure, and then send a signal to your heart saying "well, if you insist on beating so f'ing hard, will you at least beat less often?" to ease the pressure on the blood vessels, and drop your HR.
This is accomplished through a cranial nerve called the vagus nerve, which uses a nuerotransmitter called acetylcholine.
Hence, anytime your heart is beating less than 100 bpm, its because you have increased vagal tone, or increased acetylcholine. when between 60 and 100 bpm, no matter what fitness, it can be from anything, as other posters have mentioned. It is not necessarily, and likely not at all, related to your fitness level if your HR increases 10 bpm above what it was a week ago.
Most of the people who post here would have very high parasympathetic tone and would more then likely go into a Second degree AV block in the middle of the night.
Mine bottoms out around 36-37bpm in the middle of the night.