Originally Posted by
WhyFi
Wait - high HRV is a sign of stress? Or bigger swings in HRV is a sign of stress? I was under the impression that higher HRV was healthier.
When you're saying increases and decreases, you're talking relative to your baseline? Like bad stressors will send you below your baseline and good above it?
Stress is a general term denoting the influence of things, both good (exercise) and bad (sleep disruption), which disturb homeostasis, or the tendency of the system to dwell at, or return to, a particular set point.
As a homeostatic marker, i.e. an indication of what that set point is, more HRV is better because it indicates greater activity of the parasympathetic nervous system relative to sympathetic.
However, as a marker of acute perturbations, i.e., stress, good or bad, it's more complicated. Any swing away from the previous set point is indicative of stress and the system can swing in either direction. As a rule, bad stress causes an acute increase. Good stress, however seems to be able to push HRV in either direction, or at least that's my understanding, not having gone back to the original literature on "good" stress. In vague terms, I think the direction of change after exercise is an indication of how the body is "handling" stress and higher means it's reacting in a healthier way because of increased reserve. That seems to fit with my experience.
A higher day to day variance, measured in my app as the running 7-day coefficient of variation, implies stress because it means the system is being perturbed by some input.
Make sense?
I will look up acute HRV increases in response to exercise and see if there's anything interesting there.