Statement
Pacing and rest are individualised and essential management techniques for people with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and long COVID. To enhance their pacing practice and minimise post-exertional malaise (PEM), some patients use changes in their heart rate as a guide, to stay within their energy limits. By monitoring their heart rate and avoiding exceeding certain thresholds, individuals aim to prevent overexertion and reduce symptom exacerbation.
Background
People with ME/CFS experience significant energy limitations due to impaired cellular energy production and autonomic dysfunction. A key feature of the condition is post-exertional malaise (PEM), where even minimal exertion can trigger a worsening of symptoms; PEM has also been identified as a symptom of long COVID [1]. Given the unpredictability of PEM, self-management strategies such as pacing are critical for maintaining function and quality of life.
Some individuals use heart rate monitoring as a pacing tool, based on the idea that exceeding an anaerobic threshold (often estimated at 50–60% of their age-predicted maximum heart rate) may trigger PEM.
Monitoring heart rate is thought to assist pacing management by:
- Helping to define safe levels of activity
- Bringing about awareness of energy limits
- Provide warnings to indicate when your heart rate nears your limit
- Encourage modification to methods to ensure the sustainability of day-to-day activities
- Education of self and others of your limits
However, using heart rate as a strict guide for energy management has limitations. Heart rate variability is influenced by numerous factors beyond exertion, including autonomic dysfunction [2], stress, dehydration, medications, and environmental conditions. Furthermore, heart rate thresholds may not be universally applicable across all individuals with ME/CFS, as severity and physiological responses vary. Therefore, while some patients find heart rate monitoring helpful, it should be used alongside other self-monitoring techniques rather than as a sole determinant of activity limits.
Using heart rate monitoring as a pacing tool assumes that metabolic dysfunction in ME/CFS makes energy production less efficient, leading to a reliance on anaerobic pathways at lower-than-expected exertion levels.
Evidence
Research on heart rate-based pacing in ME/CFS remains limited but, provides some support for its use. The largest 2-day CPET study of ME/CFS substantiated impaired recovery in ME/CFS and confirmed that individuals with ME/CFS reach their anaerobic threshold at significantly lower workloads than healthy controls, suggesting that exertion beyond this point could contribute to PEM [3]. Additionally, Davenport et al. (2019) proposed heart rate monitoring as a tool to prevent excessive physiological strain in ME/CFS patients [4]. Anecdotal evidence and patient-reported experiences indicate that some individuals successfully use heart rate monitoring to fine-tune their pacing strategies [5]. However, no large-scale, controlled studies have confirmed its effectiveness or established optimal heart rate thresholds for energy management in ME/CFS. More research is needed to validate this approach and determine its long-term impact on symptom stability and quality of life. In conclusion, while heart rate monitoring can be a useful tool for some, it should be considered as part of a broader pacing strategy rather than a definitive guide for activity management in ME/CFS. Individual responses may vary, and patients should work with healthcare professionals to tailor their approach to their specific needs.
Emerge Australia’s Position
Based on limited clinical and available anecdotal patient experience and some research findings, Emerge Australia recommends the safe practice of pacing to minimise the effects of PEM. Whilst more research is needed, the use of a heart rate monitor may prove to be a useful tool to guide energy management and pacing. Emerge Australia welcomes future studies that elucidate the connection between an ME/CFS patient’s heartbeat, their energy limits and the safe adjustments to physical, cognitive and orthostatic activity load, to reduce the frequency and severity of PEM. More information regarding Pacing can be found on the Emerge Australia website “Pacing and Rest” Position Statement.
Patients and carers can also access our free pacing education via our website here.
References
- Appelman, B. et al. Muscle abnormalities worsen after post-exertional malaise in long COVID. Nat Commun 15, (2024).
- Nelson, M. J., Bahl, J. S., Buckley, J. D., Thomson, R. L. & Davison, K. Evidence of altered cardiac autonomic regulation in myalgic encephalomyelitis/chronic fatigue syndrome: A systematic review and meta-analysis. Medicine 98, e17600 (2019).
- Keller, B. et al. Cardiopulmonary and metabolic responses during a 2-day CPET in myalgic encephalomyelitis/chronic fatigue syndrome: translating reduced oxygen consumption to impairment status to treatment considerations. J Transl Med 22, 627 (2024).
- Davenport, T. E. et al. Chronotropic Intolerance: An Overlooked Determinant of Symptoms and Activity Limitation in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome? Front Pediatr 7, 82 (2019).
- Clague-Baker, N. et al. An international survey of experiences and attitudes towards pacing using a heart rate monitor for people with myalgic encephalomyelitis/chronic fatigue syndrome. Work 74, 1225–1234 (2023).
