Low-frequency heart rate variability is related to the breath-to-breath variability in the respiratory pattern.

HEART beat; RESPIRATION; ATTENTION; MENTAL work; PSYCHOPHYSIOLOGY; PSYCHOLOGICAL research

Changes in heart rate variability ( HRV) at 'respiratory' frequencies (0.15-0.5 Hz) may result from changes in respiration rather than autonomic control. We now investigate if the differences in HRV power in the low-frequency ( LF) band (0.05-0.15 Hz, HRVLF) can also be predicted by respiration variability, quantified by the fraction of tidal volume power in the LF ( VLF,n). Three experimental protocols were considered: paced breathing, mental effort tasks, and a repeated attentional task. Significant intra- and interindividual correlations were found between changes in HRVLF and VLF,n despite all subjects having a respiratory frequency above the LF band. Respiratory parameters (respiratory period, tidal volume, and VLF,n) could predict up to 79% of HRVLF differences in some cases. This suggests that respiratory variability is another mechanism of HRVLF generation, which should be always monitored, assessed, and considered in the interpretation of HRV changes. [ABSTRACT FROM AUTHOR]

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