Psychophysiologic effects of slow-paced breathing at six cycles per minute with or without heart rate variability biofeedback Author: Sylvain Laborde1,2, Mark S Allen3, Uirassu Borges1,4, Maša Iskra1, Nina Zammit1, Min You5, Thomas Hosang6, Emma Mosley7, Fabrice Dosseville8,9 Affiliation: <sup>1</sup> Department of Performance Psychology, Institute of Psychology, German Sport University Cologne, Cologne, Germany. <sup>2</sup> Normandie Université, UFR STAPS, EA 4260 CESAMS, Caen, France. <sup>3</sup> School of Psychology, University of Wollongong, Wollongong, New South Wales, Australia. <sup>4</sup> Department of Health &amp; Social Psychology, Institute of Psychology, German Sport University Cologne, Cologne, Germany. <sup>5</sup> Normandie Université, UFR Psychologie, EA3918 CERREV, Caen, France. <sup>6</sup> Experimental Psychology Unit, Helmut Schmidt University/University of the Federal Armed Forces, Hamburg, Germany. <sup>7</sup> Department of Sport Science and Performance, School of Sport, Health and Social Science, Solent University Southampton, Southampton, UK. <sup>8</sup> Normandie Université, UMR-S 1075 COMETE, Caen, France. <sup>9</sup> INSERM, UMR-S 1075 COMETE, Caen, France. Conference/Journal: Psychophysiology Date published: 2021 Oct 11 Other: Special Notes: doi: 10.1111/psyp.13952. , Word Count: 230 Heart rate variability (HRV) biofeedback, referring to slow-paced breathing (SPB) realized while visualizing a heart rate, HRV, and/or respiratory signal, has become an adjunct treatment for a large range of psychologic and medical conditions. However, the underlying mechanisms explaining the effectiveness of HRV biofeedback still need to be uncovered. This study aimed to disentangle the specific effects of HRV biofeedback from the effects of SPB realized alone. In total, 112 participants took part in the study. The parameters assessed were emotional (valence, arousal, and control) and perceived stress intensity as self-report variables and the root mean square of the successive differences (RMSSD) as a physiologic variable. A main effect of condition was found for emotional valence only, valence being more positive overall in the SPB-HRVB condition. A main effect of time was observed for all dependent variables. However, no main effects for the condition or time x condition interaction effects were observed. Results showed that for PRE and POST comparisons (referring, respectively, to before and after SPB), both SPB-HRVB and SPB-NoHRVB conditions resulted in a more negative emotional valence, lower emotional arousal, higher emotional control, and higher RMSSD. Future research might investigate psychophysiological differences between SPB-HRVB and SPB-NoHRVB across different time periods (e.g., long-term interventions), and in response to diverse psychophysiological stressors. Keywords: RMSSD; abdominal breathing; cardiac coherence; deep breathing; diaphragmatic breathing; heart rate variability; respiration. PMID: 34633670 DOI: 10.1111/psyp.13952