Acute Effect of a Submaximal Capacity Functional Test on Endothelial Function in Post-COVID Patients: A Cross-Sectional Observational Study.

• Grant number: 24/22713-3
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: April 01, 2025
• End date: March 31, 2026
• Field of knowledge: Health Sciences - Physiotherapy and Occupational Therapy
• Principal Investigator: Audrey Borghi Silva
• Grantee: Bárbara Rocha de Oliveira Garcia
• Host Institution: Centro de Ciências Biológicas e da Saúde (CCBS). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil

Abstract

Introduction: The six-minute step test (6MST) has proven to be a useful and low-cost tool for assessing functional capacity as well as cardiovascular and respiratory behavior in response to physical exertion. Moreover, measuring endothelial function before and after the 6MST allows for the addition of more objective parameters to facilitate the early detection of vascular changes. This also helps guide specific interventions aimed at improving functional capacity and preventing adverse events.Objective: To evaluate the acute effect of flow-mediated dilation (FMD) before and after the 6MST in post-COVID patients compared to a healthy control group. Additionally, functional variables, cardiovascular responses, and heart rate recovery after the 6MST will be assessed.Study Design and Methodology: This cross-sectional observational study will include post-COVID individuals with persistent symptoms and apparently healthy individuals. Sample characterization will include: pulmonary function tests, dyspnea sensation assessment, post-COVID functional status scale, physical activity level, functional capacity through the 6MST, chronotropic index, and FMD evaluation via brachial artery ultrasound. Parametric and non-parametric tests will be applied depending on data distribution. To identify predictors of the 6MST, univariate and multivariate linear regressions will be performed. Effect size will be calculated according to data distribution. A significance level of p < 0.05 will be established to detect statistical differences.Expected Results: It is anticipated that differences will be identified between groups in the magnitude of endothelial function response in post-COVID patients before and after the 6MST, thereby highlighting impairments in functional performance and cardiovascular responses, as well as greater intensity of limiting symptoms.