Exercise Intolerance in Long Covid After 24 Months From Severe Acute Disease: is There Room for Improvement?

Introduction: Long COVID is a complex and multisystemic condition, where dyspnea, fatigue, post-exertional malaise, cognitive impairment, decreased functional capacity, and deterioration in quality of life are the most incident clinical features. Few studies have reported cardiopulmonary alterations 24 months after severe COVID-19 infection. Objective: to evaluate the functional capacity of individuals with persistent symptoms after severe COVID-19 infection compared to control individuals without symptomatic COVID or mild COVID after 24 months. Methods: This is a case-control study assessing 34 individuals divided into 2 groups (severe COVID-19 with long COVID and a control group consisting of asymptomatic/mild acute COVID-19 with no long COVID) regarding functional capacity by 6-minute walk test (6MWT) associated with gas analysis, spirometry, respiratory muscle strength and quality of life. Results: During the 6MWT, an important lower heart rate (HR) was observed for the COVID group, with greater exertional perception, a significant decrease in the distance covered, and a low value of O ₂ uptake ( V̇ O ₂ ) and minute ventilation, in addition to very low quality of life scores, especially in aspects of functional capacity and physical limitations. Conclusion: individuals who have severe COVID-19 and persist with symptoms have low functional capacity, low V̇ O ₂ , low HR behavior, and low quality of life.