This investigation introduced 2 software programs, which compose a method (“sliding” method) for finding heart rate variability (HRV) resonance frequency (RF). The ‘Breath Pacer’ paces a small, fixed change in per-breath duration. The ‘HRVisualizer’ calculates RF in time domain by peak-trough amplitude (Gibson Research Corporation, California). The control was a widely accepted method (“jumped method”) that tests windows of stationary breath pacing (Lehrer, 2013) to meet guidelines for Fast Fourier Transform (FFT) analysis. Jumped pacing was guided by NeXus’ BioTrace+ (Mind Media, NL). FFT analysis was performed by Kubios HRV (University of Finland).

An RF value was obtained by each method for 14 participants, order counterbalanced. The jumped method tested 3-minutes of stationary pacing at 6.5, 6.0, 5.5, 5.0 and 4.5 breaths per minute (5 paces), with interbeat interval (IBI) data analyzed in Kubios HRV. The proposed method tested a 15-minute session at a fixed 0.0338 second increase in per-breath duration beginning at 6.75 and ending at 4.25 breaths per minute (78 paces). HR and breathing data were analyzed by the HRVisualizer which locates the point of maximum HR amplitude within a 60-second region of similar amplitude, and then measures exact breathing pace at that maximal location. Results of the accepted method were then compared in the HRVisualizer. Results of the proposed method were then verified in Biotrace+ as well as by visual inspection of Kubios HRV’s time-varying function. Tests of difference and correlation suggest equivalence of the methods (Z = 1.664, p = 0.096; rs(13) = 0.30227, p = 0.29354) as do the small to medium effect size (Hedges’ g = 0.433) (Ellis, 2009).

Two sets of 5-minute validation sessions were then guided by the Breath Pacer, and analyzed by FFT in Kubios HRV for LF power amplitude. Equivalence of the methods was shown (t(27) = 0.328, p < 0.746, 95% CI [−0.054, 0.074]; W(27) = 246, p = 0.339; F(27) = 2.161, p = 0.837; (r(27) = .947, p < 0.0001). Effect size was small (d = 0.216110).

Based on a 5-criteria Likert survey, participants preferred the method and design of the Breath Pacer over the BioTrace+ pacer (X²(13) = 7.0359, p = 0.008).