The Boom-Bust Cycle: Why Good Days Can Be Pacing's Biggest Trap

A day when the brain fog lifts, the legs carry you again, thoughts feel clearer – for people with ME/CFS, long Covid or POTS, this often feels like a gift. Yet exactly at this moment lies one of the most common and treacherous traps of pacing: the so-called boom-bust cycle. Anyone who uses a good day to catch up on everything that has piled up risks a crash that follows days or even weeks later. This article takes a closer look at this mechanism – and what can help against it.

What the boom-bust cycle actually is

The term describes a recurring pattern: a day with comparatively more energy ("boom") is followed by a phase of severe decline and markedly reduced capacity ("bust"). It is often described like this: on some days you feel reasonably well and hurriedly get a lot done – the "boom" period. Experts classify this pattern as a direct consequence of overexertion: the cycle of overactivity and collapse typically occurs when those affected try to ignore their symptoms and push through. The tricky part: the link between exertion and crash is rarely visible right away. As described in our article on recognising delayed exhaustion after exertion, post-exertional malaise (PEM) often only appears with a delay of one or several days. This is precisely what makes it so difficult to recognise your own limit in time – in the moment, a good day simply doesn't feel like a danger.

Why good days in particular are so risky

From the perspective of many affected people, this is paradoxical: it is precisely when things are going better that the strongest urge arises to tackle tasks that have piled up – laundry, errands, meeting friends, work that's been left undone. The desire to catch up on "normal" days is humanly understandable. Yet this very catching-up often unnoticeably crosses the individual exertion limit, also described as an "energy envelope" or energy budget. It's important to understand: a crash after overexertion is not a matter of willpower or lack of fitness, but is classified as a measurable response to disturbed energy processing – not as a character flaw or a sign of deconditioning. This applies to physical exertion just as much as to mental and emotional exertion: concentration, processing of stimuli, or emotional strain also count towards the personal energy budget, not just movement.

Pacing is not the same as total rest

Out of fear of the next crash, some affected people fall into a second, equally understandable beginner's mistake: the assumption that pacing means doing as little as possible on good days in order to rule out all risk. This falls short. Rest can be used pre-emptively – for example before an appointment or an exertion – to prevent a crash, with the explicit note that resting doesn't mean being "lazy" but is a deliberate measure to prevent PEM. Pacing therefore doesn't aim at inactivity, but at a conscious, planned balance between activity and recovery – tailored individually to one's own limits. This fundamentally distinguishes it from concepts such as gradual training build-up, as our article Pacing is not a training programme explains in more detail. Anyone who, out of fear of the bust, falls into a permanent state of over-caution merely replaces one boom-bust cycle with constant uncertainty – without addressing the actual cause, the repeated crossing of the exertion limit.

Ways out of the cycle: what can help in practice

According to the US Centers for Disease Control and Prevention (CDC), a key building block for breaking the boom-bust cycle is knowing your own individual limits for mental and physical activity and balancing activity and rest in a way that avoids PEM flare-ups. In practice, this often means:

• Breaking tasks down into smaller units and firmly scheduling rest periods, instead of getting everything done at once on good days.
• Recognising triggers for overexertion as early as possible, instead of only reacting once the crash has already set in.
• Consciously limiting activity even on good days – not because you're "not allowed" to do anything, but because feeling good doesn't automatically shift your exertion limit.

Those still at the beginning will find a good introduction to the underlying logic of this approach in our article Pacing basics: what pacing is and why it helps with PEM. Some people also find it helpful to track activity, rest and symptoms over a longer period of time, in order to make their own pattern visible in the first place – because the link between "too much" on Monday and a crash on Wednesday is very hard to reconstruct from memory alone.

A final note

How pronounced the boom-bust cycle is, and what an appropriate individual exertion limit looks like, differs considerably from person to person and can change over the course of the illness. mypacing.app is not a medical device and does not replace medical diagnosis or treatment. If symptoms persist or worsen, it is important to consult a medical professional or a specialised care team in order to assess the individual situation.

Sources

• Manage ME/CFS
• Managing Post-Exertional Malaise (PEM) Toolkit
• Boom and bust activity cycle
• Boom and bust, another ME/CFS myth?
• Post Exertional Malaise (PEM) and Rest
• Understanding Post-Exertional Malaise: Why Activity Makes You Crash