Are all measures created equal? Heart rate variability and respiration - biomed 2009.

There is considerable controversy with regards to which index of heart rate variability (HRV) is the most reliable across multiple situations. Recent evidence from Pentilla and colleagues (2001) suggests that certain indices of HRV appear to be less affected by fluctuations in respiration, and may thus be a more robust indicator of parasympathetic (vagal) influence. In the present investigation, we sought to replicate and extend this report by exploring the relations between, impedance cardiography-derived respiration parameters (rate and amplitude) and time and frequency domain indices of heart rate variability in a multiethnic sample of healthy men and women (n=39; mean age = 20.33 +/- 3.47yrs). Preliminary results support Pentilla et al.'s finding that rMSSD is relatively free of respiratory influences (r = -.06 to .21; ns), and extends this work to a multiethnic sample. In conclusion, some measures of HRV appear to be relatively free of respiratory influences while others appear less so, independent of the subjects' ethnicity.