Wichtige Begriffe rund um Long COVID, ME/CFS und POTS verständlich erklärt

Key Terms Around Long COVID, ME/CFS and POTS Explained Simply

PEM, pacing, POTS, dysautonomia, MCAS, crash and baseline explained simply – a glossary for Long COVID and ME/CFS based on established sources.

Illustration: ein aufgeschlagenes Buch mit sanft leuchtenden Begriffen auf einem Holztisch

Anyone exploring Long COVID, ME/CFS (Myalgic Encephalomyelitis/Chronic Fatigue Syndrome) or POTS quickly runs into terms that are unfamiliar in everyday life. This glossary explains the most important terms briefly and clearly, so that patients, family members and anyone interested can share a common vocabulary. This text does not replace an individual clinical assessment; it offers general orientation based on established sources.

PEM – Post-Exertional Malaise

PEM refers to a marked worsening of symptoms that typically appears with a delay of hours up to a day or two after physical, cognitive, emotional or sensory exertion. Affected areas can include fatigue, pain, difficulty concentrating or sleep disturbances, and recovery can take days to weeks. The US Centers for Disease Control and Prevention (CDC) describes PEM as one of the core features of ME/CFS and notes that even everyday activities can trigger such a setback.

Pacing

Pacing is an approach to managing one's own energy deliberately: activity, rest and recovery are balanced so that an individual's exertion threshold is not exceeded whenever possible. The goal is to reduce how often, or how severely, PEM episodes occur. Organizations such as Action for ME describe pacing as a method of observing one's own energy, recognizing patterns and planning activities accordingly – not as a rigid set of rules, but as an individual, continuously adapting process.

Energy Envelope and Spoon Theory

The energy envelope is a visual concept describing the range of available energy within which activity is possible without triggering a crash. Exceeding this range increases the risk of PEM. A well-known illustration of this idea is the so-called Spoon Theory, which represents the energy available on a given day as a limited number of "spoons" that get "spent" on individual tasks. Both concepts help make an often fluctuating capacity for activity more tangible and support more deliberate decisions about activity.

POTS – Postural Orthostatic Tachycardia Syndrome

POTS is a form of dysautonomia in which heart rate increases unusually sharply when moving from lying or sitting to standing, often accompanied by dizziness, heart palpitations, lightheadedness or fatigue. According to Dysautonomia International, it is a disorder of the autonomic nervous system that affects the regulation of circulation and heart rate during changes in posture. POTS occurs both on its own and frequently alongside Long COVID or ME/CFS.

Dysautonomia

Dysautonomia is an umbrella term for dysfunction of the autonomic nervous system, which regulates heart rate, blood pressure, digestion, temperature regulation and circulatory adjustment, among other functions. POTS is one of the best-known forms of dysautonomia, but not the only one. The range of possible signs is broad, spanning circulatory issues, digestive complaints and temperature-regulation disturbances, which is why dysautonomia is often described as a complex condition that varies considerably from person to person.

MCAS – Mast Cell Activation Syndrome

MCAS describes a condition in which mast cells – cells of the immune system – repeatedly and inappropriately release chemical mediators, which can lead to a wide range of possible signs affecting the skin, gastrointestinal tract, circulation or airways. According to the US National Institutes of Health's Genetic and Rare Diseases Information Center (GARD), this is a complex condition that is not yet fully understood and whose presentation varies considerably from person to person. MCAS is sometimes observed alongside Long COVID, ME/CFS or POTS. This section describes the concept purely for informational purposes, without making statements about individual assessment or management pathways.

Crash

"Crash" is a commonly used term for an acute, often sudden worsening of one's condition – essentially the lived experience behind the clinical term PEM. A crash can be triggered by physical, cognitive or emotional exertion, but also by stimuli such as light, noise or stress, and it is frequently accompanied by a marked drop in functioning.

Baseline

Baseline describes an individual's relatively stable underlying level of symptoms and capacity, which serves as a reference point for daily life. It differs from person to person and can change over time. Aligning one's activity level with this baseline, rather than overextending on better days, is considered a central building block of pacing approaches.

Conclusion

These terms describe interconnected aspects of a complex condition: a baseline marks the starting point, an energy envelope marks the available margin, PEM and crash describe the consequences of exceeding it, and pacing offers a way to use that margin more deliberately. POTS, dysautonomia and MCAS describe possible accompanying physical mechanisms. Knowing these terms can make it easier to make sense of one's own experience and to communicate more precisely with healthcare professionals. For an individual assessment of one's own situation, consulting qualified healthcare professionals remains essential.

Sources

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