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The utility of low frequency heart rate variability as an index of sympathetic cardiac tone: A review with emphasis on a reanalysis of previous studies


  • The compilation of this review was supported by a grant from the Spanish Ministry of Science and Innovation co-financed by FEDER funds (Proyect-n°: PSI2012-33509). Data for the pharmacological blockade study were collected at the Department of Internal Medicine at the University of Bonn (Germany) in collaboration with the University of Groningen (Netherlands). This research was supported by a grant from the Commission of the European Communities Medical and Health Research Program (Concerted Action: Quantification of Parameters for the Study of Breakdown in Human Adaptation).

Address correspondence to: Gustavo A. Reyes del Paso, Departamento de Psicología, Universidad de Jaén, 23071 Jaén, Spain. E-mail:


This article evaluates the suitability of low frequency (LF) heart rate variability (HRV) as an index of sympathetic cardiac control and the LF/high frequency (HF) ratio as an index of autonomic balance. It includes a comprehensive literature review and a reanalysis of some previous studies on autonomic cardiovascular regulation. The following sources of evidence are addressed: effects of manipulations affecting sympathetic and vagal activity on HRV, predictions of group differences in cardiac autonomic regulation from HRV, relationships between HRV and other cardiac parameters, and the theoretical and mathematical bases of the concept of autonomic balance. Available data challenge the interpretation of the LF and LF/HF ratio as indices of sympathetic cardiac control and autonomic balance, respectively, and suggest that the HRV power spectrum, including its LF component, is mainly determined by the parasympathetic system.