Good afternoon, I wrote an article on this issue. if you are interested in looking "Physiological interpretation of heart rate variability

spectral analysis data"

N.A. Chizh

I agree that HRV has limitations. However, the ratio of HF to LF does give a very good indication of sympathetic-parasympathetic balance particularly as you say you have baseline and provocative measures.

Thank you so much for the comments. After reviewing several articles, I am becoming more aware of the limitations of HRV. Based on one of the articles I came across, I am using RMSSD (low values) as indicative of increased stress during the stress procedure.

Devi Jayan

There is some debate as to whether LF/HF ratio is actually a good indication of sympa./thera. balance.

I'd also review:

1. Pinna, G., et al., The accuracy of power-spectrum analysis of heart-rate variability from annotated RR lists generated by Holter systems. Physiological measurement, 1994. 15(2): p. 163.

2. Moak, J.P., et al., Supine low-frequency power of heart rate variability reflects baroreflex function, not cardiac sympathetic innervation. Heart Rhythm, 2007. 4(12): p. 1523-1529.

3. Koenig, J., et al., Body mass index is related to autonomic nervous system activity as measured by heart rate variability—a replication using short term measurements. The journal of nutrition, health & aging, 2014. 18(3): p. 300-302.

4. Goldstein, D.S., et al., Low‐frequency power of heart rate variability is not a measure of cardiac sympathetic tone but may be a measure of modulation of cardiac autonomic outflows by baroreflexes. Experimental physiology, 2011. 96(12): p. 1255-1261.