How to Track a Post-Exertional Crash and Find Your Limit
Crashes are easy to describe and hard to demonstrate. By the time the payback lands, the effort that caused it is a day or two in the past and rarely comes to mind during a ten-minute appointment. A dated record turns a vague account of being wiped out into a sequence a clinician can actually read: what you did, how wide the gap was, how deep the dip went, how many days recovery took. That sequence is also the raw material for every pacing decision you make afterward.
What to write down for each crash
Log two things, not one: the exertion and the consequence. For the exertion, note what it was (walking, a shower, a work call, a difficult conversation), roughly how long it lasted, and how much of it was spent upright. For the crash, record the date and time symptoms turned, which gives you the delay in hours, then rate it mild, moderate or severe. Mild might mean you cut activities but stay up; moderate, mostly housebound for the day; severe, unable to leave bed or tolerate light and sound. Keep logging daily until you are back to your usual baseline so the record shows recovery length, not just onset. Alongside it, mark the symptoms that traveled with it: fatigue, brain fog, muscle aches, sore throat or tender glands, headache, palpitations, joint pain, and whether sleep left you unrefreshed. Note anything that shortened the episode, such as lying flat, fluids or a dark room.
Triggers and patterns worth watching for
Six factors are worth logging every day, whether or not you crash: physical activity, cognitive effort, rest and pacing, sleep quality, stress and time spent standing. In Trace Health these sit on the same timeline as your symptom entries, so a crash on Thursday can be read backward against Tuesday's errands and Wednesday's poor night. Patterns rarely appear in a week. Over four to six weeks you may see that crashes cluster after a specific dose, for example more than twenty minutes on your feet or two hours of screen-based concentration, and that the delay is consistent for you, often twenty-four to forty-eight hours. You may also see stacking, where three moderate days with no rest produce a crash that a single hard day would not. That personal ceiling is your energy envelope, and staying under it is easier once the numbers are visible rather than remembered.
When to bring this to a doctor
Seek prompt care for chest pain, fainting, breathlessness at rest, new focal weakness or numbness, drooping eyelids or double vision that worsen as you use the muscle, or dark cola-colored urine after exertion. A persistent fever above 38°C (100.4°F), night sweats or unintended weight loss also needs same-week assessment. Book a routine appointment if crashes have recurred for more than three months, if your baseline function is falling, or if a single episode has lasted several weeks. Bring the record. A clinician will want the delay in hours, the trigger threshold, how long recovery takes, and what your function looked like before this started. Expect questions about snoring and sleep quality, medications such as beta blockers or sedating antihistamines, and blood tests including blood count, ferritin, thyroid function, B12, vitamin D and glucose. Orthostatic vitals are often checked too.
How Trace Health supports pacing decisions
One tap records a crash the moment it starts, which matters when your hands are heavy and concentration is thin. Mild, moderate and severe are enough detail to show shape over months without turning tracking into another task that costs energy. Because exertion, standing time, sleep, stress and cognitive load are charted on the same timeline, the two-day gap that hides the cause becomes visible as a repeating offset rather than a coincidence. When you are ready to raise it, the doctor-ready PDF report lays out episode frequency, duration and the activities that preceded each one, which is far more useful in a short appointment than a spoken summary. Your health data stays on the iPhone by default with optional private iCloud sync, no account is required, and the app is available in nine languages.
Frequently Asked Questions
How long after activity does post-exertional malaise start?
Most people describe a gap of twelve to seventy-two hours, with twenty-four to forty-eight hours being common. The delay tends to be fairly consistent for one person, which is why logging the exact hour of onset is useful. Some notice an immediate slump that then deepens the next day, so record both. The gap is the feature that separates this from ordinary tiredness, which follows effort within minutes to hours and lifts after a night of sleep. Over several weeks your entries will show your own typical lag, and that number becomes the thing you plan around.
How do I work out my energy envelope?
Work backward from crashes rather than forward from goals. For four to six weeks, record daily activity in plain terms (minutes walking, minutes upright, hours of concentrated thinking) and mark every crash. Then look at the two or three days before each one. The level you can repeat day after day without payback is your envelope, and it is usually lower than the level you can manage once. Test changes one at a time, in small increments, and give each change a couple of weeks. Discuss the results with your clinician, especially before any structured increase in activity.
Is a post-exertional crash the same as being out of shape?
They behave differently over time, which is why a log helps. Deconditioning improves gradually as activity is repeated, and the tiredness it causes arrives during or just after effort. A post-exertional crash is delayed, out of proportion to what was done, and tends to worsen rather than improve when activity is pushed upward. Recovery also takes days rather than hours, and it usually drags a cluster of other symptoms with it, such as fog, aching and unrefreshing sleep. Several weeks of entries showing that pattern give your clinician something concrete to assess.
Your health data stays on your iPhone.
No account. Private. No personal information is ever requested. Your health data stays on your iPhone by default. A backup option to your private iCloud is available. Trace Health never collects or sells your health data.
What people say
Rated 4.8 out of 5 from 50+ ratings on the App Store.
- “Very clean and well organized, nicely customizable. Practical widgets for the home screen. Exactly what I was looking for, thanks 👍” (jxleya, Germany)
- “I highly recommend this app, no annoying ads etc, straight to the point of keeping a track of health symptoms, the best health monitor app I have ever used.” (Trisroy-Best, United Kingdom)