How could the level heart rate variability be an indicator of the level of sympathetic or vagal control?

It is. Our regular heart rate which is slower than the intrinsic rate is the balance between the sympathetic and vagal inputs to the sinus node at any time with the latter dominating.This causes beat to beat variation specially noticeable during respiration Parasympathetic activity is represented by reduced variation in time domain and dominance of hi frequency oscillations in the spectral analysis.

Related Questions

Is heart rate variability a good way to measure stress and are there at-home devices/software for doing it? (maybe chest strap-app combos)?

No. Heart rate variability is actually a sign of a healthy heart, not stress. Your heart rate should vary throughout the day, in response to a multitude of factors. Commercial heart rate monitors do measure HR accurately, and can be used to track your fitness level over time. Hope this helps! Read more...

My heart rate variability at rest is extremely high (RMSSD >300), can that be a cause of concern?

YES. Please immediately go to a cardiologist or ER to have your rate checked on a monitor and you will need and EKG and echocardiogram as well as medication to control your rate. Read more...

Does heart rate variability predict death?

Define 'VARIABILITY" You must fill in the details and indicate the reason for this peculiar question. Read more...

Biofeedback - which is more accurate for generalized anxiety, galvanic skin response or heart rate variability?

HRV. I can speak for heart rate variability and say that it is an accurate and powerful way to assess biofeedback. We have used hrv based devices in our clinic with good response. Read more...
Individual matter. Biofeedback can be very effective for some, but not at all for other people. Similarly, gsr & hrv variations of biofeedback vary in effectiveness depending upon the individual, and to some extent, the clinician. You will need to see which, if either, gives you worthwhile protection from anxiety. Read more...
Combination. The best form of biofeedback is using as much information as possible which would include both galvanic skin response and heart rate variability. Read more...