Fatigability in patients with Long COVID syndrome: Investigation of physiological and perceptual mechanisms

• Grant number: 23/04814-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: October 01, 2023
• End date: July 31, 2024
• Field of knowledge: Biological Sciences - Physiology
• Principal Investigator: Bruno Moreira Silva
• Grantee: Eduardo Lourenço Cilli
• Host Institution: Escola Paulista de Medicina (EPM). Universidade Federal de São Paulo (UNIFESP). Campus São Paulo. São Paulo , SP, Brazil

Abstract

Chronic Fatigue Syndrome (CFS) is a complex disease, also known as myalgic encephalomyelitis, responsible for causing persistent mental and physical fatigue resulting in the inability to perform daily tasks, negatively impacting the quality of life. This disease still has its etiology and pathophysiology unknown, and it is a great challenge to make its diagnosis due to the variety of nonspecific symptoms, lack of a biomarker, and lack of a specific clinical analysis method. This leads to false diagnoses of depression or burnout, difficulting the correct treatment and generating false data on the prevalence of CFS. During the pandemic of COVID-19, CFS was highlighted in the clinical and research sphere, because part of the patients with long COVID-19 reported muscle fatigue, even without cardiorespiratory diseases and with mild cases of the disease in its acute phase. Thus, the current hypothesis, not yet confirmed, is that the virus crosses the blood-brain barrier (BHE) and reaches brain regions responsible for the sensation of effort and fatigue causing dysfunction or death of neurons, weakening this region and generating an exacerbated sensation of effort and fatigue when performing physical and mental activities. However, no objective tests have been done to analyze the presence of this disease in patients with long COVID. There is one technique that objectively analyzes the presence of CFS, the handgrip strength test. However, although it has been tested, it has not been done in patients with long COVID but with other diseases such as cancer and other viral infections. Furthermore, there has been no description of perceptual, neural and cardiovascular responses that could help clarify mechanisms underlying the generation of fatigue in CFS. With this, the present study, aims to perform a comparative analysis of measures of perceived exertion and fatigue, blood pressure response, heart rate, muscle oxygenation, strength and muscle electrical activity between healthy people and people with COVID Long without cardiorespiratory diseases in order to obtain clues about mechanisms of fatigue generation and parameters to interpret physiological and perceptual responses in patients with COVID Long who have CFS.