HEART RATE VARIABILITY:
PART 1.

Ever wonder why you’re tired or feeling off and not rested enough? These fitness trackers and HRV monitoring may give you some better and more specific reasons.

What is HRV? 

It’s the variability in the timing between the beats of your heart. If your heart beats 60 times in a minute, it’s not once every second, but sometimes it could be 1.1 seconds, sometimes 0.95, etc. The variability comes from competing inputs from your nervous system.

Sympathetic and Parasympathetic are the two branches of the autonomic nervous system. 

The do stuff, activating part (sympathetic), and the rest/digest, slow down, recover (parasympathetic). 

When both are giving instructions to the heart, it causes variability, which is always going on to different degrees.  When those systems are well balanced, you see a lot of variabilities because they are both signalling and getting their way.  So HRV is a signal of your nervous system being balanced.