PEM Tracker
Post-exertional malaise tracking for ME/CFS and long COVID
PEM Tracker combines data from a wearable device with a short daily questionnaire to help people living with ME/CFS and long COVID recognise post-exertional malaise — ideally early enough to act on it.
Post-exertional malaise is delayed and disproportionate. A crash often follows exertion by a day or more, which makes cause and effect genuinely hard to see from the inside. Continuous measurements such as heart rate variability, resting heart rate, and body temperature deviation often shift before symptoms are consciously noticed. Pairing those signals with what you actually felt each day makes the pattern easier to see.
How it works
- You sign in with Google. No password is created or stored here.
- You optionally connect a wearable, approving exactly which data categories are shared.
- You answer a short daily questionnaire about symptoms and exertion.
- The dashboard shows those signals together, with a PEM estimate calibrated to you.
Calibration takes time
The detection thresholds are individual. What signals a crash for one person is ordinary variation for another, so the model is tuned per person against your own labelled good and bad periods. This means early estimates are provisional and become more useful as your history grows. An uncalibrated score is worse than no score, and the interface says so rather than presenting false confidence.
Privacy
Data is stored on privately operated hardware in Alberta, Canada. It is never sold or shared, and there are no analytics or trackers. You can delete everything, permanently, at any time. Full detail is in the Privacy Policy.
How it is built
Handling somebody else's health record is the difficult part of a project like this, not the charts. So the separation between accounts was built first, before any device integration existed, and the rest is being added on top of it rather than retrofitted around it.
In practice that means each account's data sits outside the web server's reach entirely, and every request has to establish which account it belongs to before anything is read — being on the right network is not treated as proof of identity. Access to a record is logged, including access by the operator, and the log is written so that later alteration of it can be detected.
None of that makes a system unbreakable, and the Privacy Policy is deliberate about what these measures do and do not cover — including the parts that are still limitations.