Fagan et al. (2026)
- Authors: Cory Donald Fagan, Eleanor Stein, Jane Shearer, Keely A. Shaw
- Institutes: Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
- Publisher: Fatigue: Biomedicine, Health & Behavior
- Link: DOI
Summary
This paper establishes a crucial link between the clinical symptom of post-exertional malaise (PEM) and objective metabolic dysfunction. By providing a framework to translate complex exercise test data into daily pacing strategies, it offers a pathway for safe, harm-reducing rehabilitation. This shift from standard exercise protocols to PEM-informed management is vital for preventing the cycle of symptom exacerbation in Long COVID patients.
What was researched?
The study proposed a physiological decision-making framework for Long COVID that reconceptualizes post-exertional malaise (PEM) as an objective impairment of recovery. It investigated how metrics from specialized exercise testing can be used to guide safe rehabilitation and activity management.
Why was it researched?
Standard rehabilitation protocols often cause harm to patients with Long COVID or ME/CFS due to post-exertional malaise. There is a critical need for objective markers to identify metabolic limits and prevent the ‘push-crash’ cycle common in these conditions.
How was it researched?
The authors synthesized current evidence from serial (2-day) cardiopulmonary exercise testing (CPET) to identify reproducible physiological abnormalities. They developed a framework to translate these metabolic markers into clinical metrics for pacing and activity progression.
What has been found?
The researchers found that PEM can be objectively identified through abnormalities in respiratory and metabolic variables during repeat exercise. These findings allow for the creation of individualized ‘safe zones’ for activity, specifically by identifying the heart rate at the anaerobic threshold. This framework enables clinicians to set intensity limits that minimize the risk of symptom flare-ups.
Discussion
The study highlights the limitation of relying solely on subjective patient reports for managing activity. While the framework provides a robust physiological basis for pacing, it requires clinicians to have access to specialized testing equipment and expertise in interpreting metabolic data.
Conclusion & Future Work
Safe rehabilitation for Long COVID is possible if it is informed by the patient’s individual physiological recovery capacity. The authors recommend using metabolic testing to support functional stability and improve quality of life while strictly avoiding overexertion.