Towards an understanding of physical activity-induced post-exertional malaise: Insights into microvascular alterations and immunometabolic interactions in post-COVID condition and myalgic encephalomyelitis/chronic fatigue syndrome.
Haunhorst, Simon, Dudziak, Diana, Scheibenbogen, Carmen et al. · Infection · 2025 · DOI
Quick Summary
This review examines why people with ME/CFS and long COVID feel much worse after physical activity—a condition called post-exertional malaise. The researchers found that when these patients exercise, their bodies struggle to use oxygen properly and produce energy efficiently, likely due to problems with tiny blood vessels and lingering immune activation. This causes a buildup of harmful substances like lactate and triggers further inflammation and exhaustion.
Why It Matters
Understanding the biological mechanisms behind post-exertional malaise is crucial because it affects most ME/CFS patients profoundly and remains poorly understood. This comprehensive review connects multiple organ systems—circulation, energy production, and immunity—suggesting that PEM is not simply deconditioning or psychological, which validates patient experiences. The findings may guide development of targeted treatments and inform safer activity management strategies for affected patients.
Observed Findings
- Patients with PCC and ME/CFS exhibit reduced systemic oxygen extraction and decreased oxidative phosphorylation capacity during physical activity.
- Mitochondrial dysfunction and microcirculatory impairments are evident in both conditions and appear maintained by latent immune activation.
- Physical exertion triggers accumulation of metabolites including lactate, reactive oxygen species, and prostaglandins that activate immune responses.
- Patients frequently experience tachycardia, dyspnea, and early activity cessation during exertional episodes.
- Metabolic dysfunction appears coupled with ionic disturbances in muscle and modulation of central nervous system function.
Inferred Conclusions
- Post-exertional malaise arises from interconnected deficits in tissue perfusion, oxygen utilization, and bioenergetic flexibility triggered by physical activity.
- Latent immune activation perpetuates both mitochondrial and microvascular dysfunction, creating a self-sustaining cycle of reduced energy production.
- Accumulation of metabolic byproducts and reactive oxygen species intensifies immune activation and symptom exacerbation during and after exertion.
- The pathophysiology involves multiple organ systems (muscular, vascular, immune, neurological) in a coordinated dysregulation rather than a single primary defect.
Remaining Questions
- Which specific microvascular alterations are primary drivers of reduced oxygen extraction versus compensatory responses?
- What distinguishes latent immune activation in PCC/ME/CFS from normal post-viral immune states, and what maintains its persistence?
- Can biomarkers of mitochondrial dysfunction or microcirculatory impairment reliably predict or stratify PEM severity?
- What interventions effectively break the cycle of immune activation and bioenergetic inflexibility without worsening symptoms?
What This Study Does Not Prove
This review does not prove causation or establish which mechanism is primary versus secondary; the relationships described may be bidirectional or interdependent. It does not validate any specific treatment or provide clinical trial evidence for interventions. The review synthesizes existing evidence but does not introduce new experimental data that definitively confirms the proposed mechanistic model in human subjects.
Topics
Tags
Metadata
- DOI
- 10.1007/s15010-024-02386-8
- PMID
- 39240417
- Review status
- Editor reviewed
- Evidence level
- Established evidence from major reviews, guidelines, or evidence maps
- Last updated
- 7 April 2026