Slow-Paced Breathing: Influence of Inhalation/Exhalation Ratio and of Respiratory Pauses on Cardiac Vagal Activity

Abstract

Slow-paced breathing has been shown to enhance the self-regulation abilities of athletes via its influence on cardiac vagal activity. However, the role of certain respiratory parameters (i.e., inhalation/exhalation ratio and presence of a respiratory pause between respiratory phases) still needs to be clarified. The aim of this experiment was to investigate the influence of these respiratory parameters on the effects of slow-paced breathing on cardiac vagal activity. A total of 64 athletes (27 female; Mage = 22, age range = 18–30 years old) participated in a within-subject experimental design. Participants performed six breathing conditions within one session, with a 5 min washout period between each condition. Each condition lasted 5 min, with 30 respiratory cycles, and each respiratory cycle lasted 10 s (six cycles per minute), with inhalation/exhalation ratios of 0.8, 1.0, 1.2; and with or without respiratory pauses (0.4 s) between respiratory phases. Results indicated that the root mean square of successive differences (RMSSD), a marker of cardiac vagal activity, was higher when exhalation was longer than inhalation. The presence of a brief (0.4 s) post-inhalation and post-exhalation respiratory pause did not further influence RMSSD. Athletes practicing slow-paced breathing are recommended to use an inhalation/exhalation ratio in which the exhalation phase is longer than the inhalation phase.

Psychophysiological effects of slow‐paced breathing at six cycles per minute with or without heart rate variability biofeedback

“…The absence of difference in CVA between both conditions may suggest that the participants adjusted adequately their breathing pattern during SPB-NoHRVB even without visualizing the heart rate biofeedback signal. The increase of CVA observed with SPB and its subsequent decrease after completing the SPB task is in line with previous research (e.g., Hoffmann et al, 2019;Laborde, Iskra, et al, 2021;You, Laborde, Salvotti, et al, 2021), illustrating that the short-term effects of SPB on CVA are similar to the action of a "switch-on/switch-off" power switch, with CVA returning to baseline immediately after SPB stops. Nonetheless, preliminary evidence indicates that chronic increases in resting CVA can also be achieved with a longterm SPB-NoHRVB intervention (15 min/day during 30 days) (Laborde et al, 2019).…”

“…Future research may consequently clarify the amount of training necessary to achieve a positive emotional experience with SPB and to which extent the use of biofeedback may contribute to potentially accelerate this process. ( 7) We tested only one modality of SPB and future research could manipulate the characteristics of SPB, such as testing different inhalation/exhalation ratios (Bae et al, 2021;Laborde, Iskra, et al, 2021;Van Diest et al, 2014), and the presence of a respiratory pause between respiratory phases (Laborde, Iskra, et al, 2021;Russell et al, 2017). ( 8) Future research might also consider testing the effects of HRV biofeedback when negative emotions are elicited and initial arousal is not low, for example, in reaction to psychological or physical stressors, as suggested by Szulczewski and Rynkiewicz (2018).…”

“…Specifically, SPB increases RSA amplitude, the peak-to-trough heart rate difference in the breathing cycle (Cooke et al, 1998). In SPB, the inhalation and exhalation periods are controlled ("paced"), with exhalation being longer than inhalation-a pattern that provokes higher increases in the RSA (Bae et al, 2021;Laborde, Iskra, et al, 2021;Van Diest et al, 2014). SPB is usually realized at a pace of around six cycles per minute (cpm), while the spontaneous breathing frequency generally comprises between 12 and 20 cpm (Sherwood, 2006;Tortora & Derrickson, 2014).…”

Single Slow-Paced Breathing Session at Six Cycles per Minute: Investigation of Dose-Response Relationship on Cardiac Vagal Activity

“…Different parameters have been found to differentially influence the effectiveness of SPB, for example, the inhalation/exhalation ratio. A longer exhalation in relation to inhalation was found to trigger more psychophysiological benefits [ 4 , 5 , 6 ]. Another aspect which has not yet received researchers’ attention to date is the dose-response relationship.…”

“…Therefore, in this study, we focus particularly on SPB implemented without biofeedback, in which SPB is practiced without the live display of a biological signal [ 26 ], such as the RF, heart rate or HRV [ 11 , 27 ]. Concerning studies involving a single-session SPB without biofeedback and CVA, durations from 3 [ 28 ], 5 [ 4 , 5 , 29 , 30 ], 15 [ 23 , 31 , 32 ], and up to 30 min [ 33 ] have been used in previous research. Few studies adopted a design including CVA measurement during and after SPB, but existing findings indicate an increase in CVA during SPB with a return to baseline levels upon the cessation of SPB.…”