Review Mechanisms and Severity of Exercise Intolerance Following COVID-19 and Similar Viral Infections: A Comparative Review 2023 Weldon et al

Abstract
Approximately 19% of the population is suffering from “Long COVID”, also known as post-acute sequelae of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (PASC), which often results in exercise intolerance. As COVID infections continue to be common, studying the long-term consequences of coronavirus disease (COVID) on physical function has become increasingly important. This narrative review will aim to summarize the current literature surrounding exercise intolerance following COVID infection in terms of mechanism, current management approaches, and comparison with similar conditions and will aim to define limitations in the current literature.

Multiple organ systems have been implicated in the onset of long-lasting exercise intolerance post-COVID, including cardiac impairment, endothelial dysfunction, decreased VO2 max and oxygen extraction, deconditioning due to bed rest, and fatigue. Treatment modalities for severe COVID have also been shown to cause myopathy and/or worsen deconditioning. Besides COVID-specific pathophysiology, general febrile illness as commonly experienced during infection will cause hypermetabolic muscle catabolism, impaired cooling, and dehydration, which acutely cause exercise intolerance. The mechanisms of exercise intolerance seen with PASC also appear similar to post-infectious fatigue syndrome and infectious mononucleosis. However, the severity and duration of the exercise intolerance seen with PASC is greater than that of any of the isolated mechanisms described above and thus is likely a combination of the proposed mechanisms. Physicians should consider post-infectious fatigue syndrome (PIFS), especially if fatigue persists after six months following COVID recovery. It is important for physicians, patients, and social systems to anticipate exercise intolerance lasting for weeks to months in patients with long COVID.

These findings underscore the importance of long-term management of patients with COVID and the need for ongoing research to identify effective treatments for exercise intolerance in this population. By recognizing and addressing exercise intolerance in patients with long COVID, clinicians can provide proper supportive interventions, such as exercise programs, physical therapy, and mental health counseling, to improve patient outcomes.

Open access, https://www.cureus.com/articles/153...ilar-viral-infections-a-comparative-review#!/

 

What a mess of an article. Just two examples

"Post-Infection Fatigue Syndrome (PIFS)

As discussed above, there is an acute decrease in strength and endurance immediately following a febrile illness. However, in some patients, symptoms may persist and result in chronic exercise intolerance and long-term fatigue, termed post-infection fatigue syndrome (PIFS). When symptoms of fatigue persist for six months or more following infection, a diagnosis of PIFS may be considered [16]. The mechanism behind PIFS is complex and not well understood, but some studies have shown evidence of decreased cerebral oxygen consumption and blood flow as well as a discrepancy between feelings of fatigue and lack of actual muscle weakness [17]. While muscle strength is maintained, muscle recovery has been shown to be impaired during PIFS. This may be due to a lack of blood flow, impairing the delivery of oxygen and removal of waste from the muscles, and thus delayed muscle recovery and low tissue oxygen saturation may be indicative of PIFS. It is important to note that PIFS occurs more frequently with specific infections, namely, infectious mononucleosis caused by the Epstein-Barr virus. PIFS as a component of long COVID, however, is a current topic of interest for researchers, as many patients are reported to experience PIFS for months following COVID infection [16]."

And eventually CFS appears,
"While most cases of EBV will resolve without long-term sequelae, it is possible to develop chronic fatigue syndrome (CFS), characterized by persistent fatigue and sleep problems that can present as exercise intolerance."

 

There is obviously no need for almost any of this if the exertion intolerance is fixed. This is ridiculous. The infinite belief in rehabilitation magically getting sick people back to function is absurd. It's almost like they're treating this as a business opportunity when instead it's a giant resource vacuum.