Correlation between different linear and nonlinear analysis methods in the assessment of cardiac autonomic modulation in healthy men and women with different levels of cardiorespiratory fitness.

• Grant number: 25/07895-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: August 01, 2025
• End date: July 31, 2026
• Field of knowledge: Health Sciences - Physiotherapy and Occupational Therapy
• Principal Investigator: Hugo Celso Dutra de Souza
• Grantee: Annick Beatriz Oliveira Dias de Macedo
• Host Institution: Faculdade de Medicina de Ribeirão Preto (FMRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

This study investigates the correlation between linear and nonlinear methods in the analysis of heart rate variability (HRV) in 172 healthy individuals, stratified according to cardiorespiratory fitness, based on maximum oxygen consumption (VO¿ max). It is evident that HRV is a physiological marker widely used to assess autonomic modulation of the heart, investigating the dynamic interaction between both the sympathetic and parasympathetic components of the autonomic nervous system (ANS) with respect to the sinoatrial node. Therefore, specialized software such as CardioSeries v2.4 and Kubios HRV Standard 3.4.3 will be used to analyze cardiac signals, enabling the extraction of parameters in the time domain (SDNN, RMSSD, pNN50) and in the frequency domain, through the Fast Fourier Transform (FFT), which decomposes the electrocardiographic signals into their spectral components, enabling the quantification of sympathetic and parasympathetic activity through the low (LF) and high frequency (HF) bands. In parallel, nonlinear approaches, including the Poincaré plot, symbolic analysis and entropy (ApEn and SampEn), will be used to characterize complex patterns of autonomic modulation. In summary, the integration of these methodologies seeks to improve the accuracy in the assessment of cardiovascular homeostasis, providing support for the identification of predictive biomarkers and optimization of both clinical and scientific applications aimed at cardiovascular rehabilitation and the prescription of individualized exercises.