Autonomic dysfunction and exercise intolerance in post-COVID-19 - An as yet underestimated organ system?

Grigor

Senior Member (Voting Rights)
Schwendinger a 1, V.N. Looser b 1, M. Gerber b 2, A. Schmidt-Trucksäss Dvision of Sports and Exercise Medicine.

Abstract:

Individuals recovering from COVID-19 often present with persistent symptoms, particularly exercise intolerance and low cardiorespiratory fitness. Put simply, the Wasserman gear system describes the interdependence of heart, lungs, and musculature as determinants of cardiorespiratory fitness.

Based on this system, recent findings indicate a contribution of peripheral, cardiovascular, and lung diffusion limitations to persistent symptoms of exercise intolerance and low cardiorespiratory fitness. The autonomic nervous system as an organ system involved in the pathophysiology of exercise intolerance and low cardiorespiratory fitness, has received only little attention as of yet.

Hence, our article discusses contribution of the autonomic nervous system through four potential pathways, namely alterations in (1) cerebral hemodynamics, (2) afferent and efferent signaling, (3) central hypersensitivity, and (4) appraisal and engagement in physical activity.
These pathways are summarized in a model.

Consequently, this article encourages a shift in perspective by examining the state of the pulmonary and cardiovascular system, the periphery, and auxiliary, the autonomic nervous system as potential underlying mechanisms for exercise intolerance and low cardiorespiratory fitness in patients with post-COVID-19."

https://www.sciencedirect.com/science/article/pii/S1697260023000650?via=ihub
 
Their logic seems, as exercise specialists, to look for why people with Long Covid experience exercise intolerance. They are accustomed to looking to the lungs, heart and muscles for explanations, and diagnosing deconditioning.
In Long Covid, they find these don't provide adequate explanation, so they are looking for BPS style psychological or psychobiological explanations and decided that HPA axis stress responses and brainfog/psychological responses are the problem. It's not clear whether they have decided whether this is under voluntary control or not.

I haven't read every word, but I only saw one mention in passing of PEM. They don't seem to have understood that at all.
 
Gotta love the "*may also occur in the brain".

The ANS is proposed to use two sensations to regulate exercise performance, namely feedback on physical strain and psychological effort required to sustain a task (Swart et al., 2012). Considering the high psychological burden imposed on patients with post-COVID-19 (Han et al., 2022; Schaeffer et al., 2022; Shanbehzadeh et al., 2021), it seems plausible that changes in central regulations might lead to an exacerbation of psychological effort during high-intensity exercise – herein referred to as central hypersensitivity.

Central hypersensitivity might be mediated through fatigue (Schaeffer et al., 2022; Swart et al., 2012). Physiological factors such as systemic inflammation, immune activation, and mitochondrial damage have been shown to worsen fatigue and as a result may amplify the experienced psychological effort (Morris et al., 2015). This has been demonstrated in patients with post-COVID-19 (Ajčević et al., 2023; Qin et al., 2021) and patients with ME/CFS (Boissoneault et al., 2019; van Campen et al., 2021). The ceiling of maximum tolerable physical and psychological effort might thus be reached earlier, i.e. at a lower exercise intensity compared to healthy individuals with similar CRF (see Fig. 1). For some individuals, this might even be the case during activities of daily life. Quantifying physical and psychological effort separately during CPET (i.e. Borg scale for physical and Task Effort and Awareness scale for psychological effort) (Swart et al., 2012) in both patients with post-COVID-19 and healthy matched controls might, therefore, be beneficial.


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Psychological effort? For exercise? This is ridiculous and doesn't make any pathophysiological sense. PEM experienced after standing upright or overdoing ADL is not psychological in origin. I can safely say that my psychological capacity frustratingly and consistently always far exceeds my exercise capacity. There is also incorrect use of the term central hypersensitivity. Sorry, I can't bring myself to read the whole paper it sounds so much like more make-uppy pseudoscience.
 
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