Contribution of visual feedback to the effectiveness of a diaphragmatic breathing program on anxiety levels in adults

Abstract

Introduction

Anxiety constitutes a profound dysregulation of the Autonomic Nervous System (ANS), manifested by constant sympathetic hyperactivation and a loss of autonomic flexibility or "vagal brake." Conventional relaxation techniques typically lack an immediate feedback mechanism, preventing both the subject and the clinician from having biological certainty regarding the modification of the desired physiological parameters. Sustained by the Neurovisceral Integration Model, this project addresses Respiratory Sinus Arrhythmia (RSA) at a resonance frequency (0.1 Hz) to stimulate the vagal pathway and activate baroreflexes, promoting psychological resilience and emotional self-regulation.

Objective

To evaluate the effectiveness of a diaphragmatic breathing program assisted by continuous visual feedback in an adult population with moderate to high anxiety levels, compared to respiratory training based exclusively on verbal instruction, analyzing a statistically significant decrease in anxiety levels as the primary outcome.

Methodology

A protocol with a repeated-measures experimental design with intent to register before the corresponding committees of the INR LGII. The sample will consist of 30 adult subjects; this size is justified by its nature as a pilot study, oriented towards evaluating the operational feasibility of the digital ecosystem and estimating the variance of the variables for definitive sample size calculation.

Assignment to the study arms (Experimental Group: training with a photoplethysmography [PPG] sensor and visual guide; Control Group: verbal guide only) will be performed via simple automated randomization. To control for confounding biases, the study will implement strict blinding for the data analyst (who will process the biometric and psychometric matrices without knowing the group assignment). The confidentiality of the subjects will be respected according to international ethical guidelines.

Primary variables: anxiety levels (psychological), Heart Rate Variability (HRV, RMSSD index, quantitative physiological), and perceived anxiety level (subjective). The intervention will comprise 1 weekly 30-minute session for 6 weeks. The measurements will be:

• Anxiety: Two measurements will be taken (one baseline and another upon completion of the 6 sessions) using the Beck Anxiety Inventory (BAI).
• HRV (RMSSD): Measured via an optical PPG sensor, recorded during the 6 sessions for each subject throughout the program.
• Perceived anxiety: One measurement will be applied per session (at the end of the therapy, totaling 6 evaluations) using a 0–10 Visual Analog Scale (VAS).

Statistics

Quantitative information will be summarized using measures of central tendency and dispersion. Inferential analysis of temporal changes will be conducted using a repeated-measures ANOVA, depending on the parametric or non-parametric nature of the sample. It will be complemented by the calculation of the effect size (Cohen's d) under the intention-to-treat (ITT) principle.

Conclusions

This digital health pilot project seeks to validate a low-cost, high-precision protocol for autonomic modulation. It is anticipated that visual feedback will mitigate the clinical risks of uncompensated hyperventilation present in traditional verbal instruction, offering a standardized, replicable tool for evidence-based clinical practice.