Abstract
Persistent symptoms and vascular impairment are common among individuals recovering from COVID-19, yet little is known about acute interventions capable of improving endothelial function in this group. Submaximal functional tests, such as the six-minute step test (6MST), provoke marked cardiovascular activation and may provide a brief stimulus for vascular adaptation. This study examined whether performing a single 6MST session could trigger an immediate enhancement in brachial artery endothelial function in adults with long COVID. Forty-seven participants, symptomatic long COVID individuals and healthy controls, underwent evaluations of respiratory function, fatigue, dyspnoea, habitual physical activity, and functional capacity. Cardiorespiratory responses during the 6MST were measured with a portable metabolic system, and flow-mediated dilation (FMD) of the brachial artery was assessed before exercise and 10–15 min afterward. At baseline, the long COVID group demonstrated greater adiposity, a higher burden of comorbidities, reduced functional capacity, lower peak V̇O2, and attenuated FMD relative to controls. A single bout of submaximal test acutely improves brachial artery endothelial function in individuals with persistent symptoms following COVID-19. These participants also displayed reduced functional capacity and peak VO2, greater diastolic blood pressure response, and increased lower limb fatigue during the test. Although VO2 peak showed a modest association with the FMD% response in univariate analysis, this relationship did not persist after adjustment for confounders, indicating that the acute vascular improvement was not independently determined by cardiorespiratory fitness.
Data availability
The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.
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Acknowledgements
To the Coordination for the Improvement of Higher Education Personnel (CAPES), National Council for Scientific and Technological Development (CNPq), and São Paulo Research Foundation (FAPESP). To the University Hospital of Federal University of São Carlos - SP-Brazil (HU-UFSCar) Brazilian Company of Hospital Services (EBSERH). Professor Ph.D. Audrey Borghi-Silva is CNPq Research Productivity Scholarship - Level 1B. Professor Daniela Bassi-Dibai is currently a recipient of the Research Productivity Grant from the Foundation for Support of Research and Development in Science and Technology of Maranhão (FAPEMA).
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This study was supported by an undergraduate research scholarship from São Paulo Research Foudation (FAPESP – process number: 24/22713-3), which had no role in study design, data collection, analysis, or publication decisions.
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Conceptualization: ADS, BROG, DB, NFSJ, PAR, PFC, KTMM, SAP, RA, AB; Data curation: ADS, AB; Formal Analysis: ADS, AB; Validation: ADS, BROG, DB, NFSJ, PAR, PFC, KTMM, SAP, RA, AB; Visualization: ADS, BROG, DB, NFSJ, PAR, PFC, KTMM, SAP, RA, AB; Writing – original draft: ADS, BROG, DB, NFSJ, PAR, PFC, KTMM, AB; Writing – review & editing: ADS, BROG, DB, NFSJ, PAR, PFC, KTMM, SAP, RA, AB.
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Santos-de-Araújo, A.D., de Oliveira Garcia, B.R., Bassi-Dibai, D. et al. A single bout of submaximal aerobic functional capacity test acutely promotes endothelial function in long COVID patients. Sci Rep (2026). https://doi.org/10.1038/s41598-026-41182-2
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DOI: https://doi.org/10.1038/s41598-026-41182-2
