Post-COVID-19 syndrome: Impact of fatigue and dyspnea on functional capacity and quality of life

Abstract

Introduction: Post-COVID-19 syndrome can present persistent manifestations that impact various dimensions of health and functionality. Fatigue and dyspnea are notable among the symptoms investigated; they may be associated with exercise intolerance, reduced exercise capacity, altered pulmonary function, and impaired quality of life, making it important to understand their medium- and long-term effects. Objective: To analyze scientific evidence regarding the impact of fatigue and dyspnea on the functional capacity and quality of life of individuals with post-COVID-19 syndrome, considering their effects on exercise tolerance, pulmonary function, mobility, and physical performance. Methods: This is a qualitative and descriptive integrative literature review. Searches were conducted in the PubMed/MEDLINE, SciELO, and BVS databases using descriptors and keywords related to post-COVID-19 syndrome, long COVID, fatigue, dyspnea, functional capacity, exercise tolerance, and quality of life, combined using the Boolean operators AND and OR. Results: Initially, 110 records were identified; 40 were removed due to duplication, leaving 70 for screening. Subsequently, 40 articles were evaluated for eligibility, and ultimately, 11 studies met the established criteria and comprised the final sample. The analysis was descriptive and qualitative, considering the study designs, objectives, and main outcomes of the selected studies. The 11 analyzed studies demonstrated that fatigue and dyspnea are significant manifestations of post-COVID-19 syndrome and are associated with alterations in exercise capacity, exertion tolerance, pulmonary function, mobility, functional performance, and quality of life. Various mechanisms related to functional limitation were identified, including deconditioning, ventilatory abnormalities, circulatory and peripheral limitations, impaired oxygen extraction, and dysfunctional breathing. Studies utilizing cardiopulmonary exercise testing highlighted the importance of assessing parameters such as peak VO₂, ventilation, gas exchange, and circulatory response in understanding persistent exercise intolerance. Impacts persisting into medium- and long-term follow-ups were also observed. Evidence regarding rehabilitation suggested potential benefits for symptoms, physical function, physical activity, and quality of life, although study heterogeneity limits the determination of the magnitude and consistency of these effects. Conclusion: Fatigue and dyspnea are associated with significant impacts on the functional capacity and quality of life of individuals with post-COVID-19 syndrome. The identified limitations are multifactorial in nature, underscoring the need for multidimensional assessment, individualized follow-up, and rehabilitation strategies tailored to each patient's functional needs. Further studies with greater methodological standardization and longitudinal follow-up are required to enhance our understanding of the progression of these manifestations and their functional consequences.