Long Covid patients often face post-exertional malaise (PEM).

One of the main treatments for Long Covid is graded exercise therapy. This works for some subset of patients. But for other patients, it actually makes things worse. Right now we have no objective test that tells who is in what category.

I like this study since it identifies a specific mechanism of why PEM happens. And maybe that will lead to a more objective test for different sub-types of long covid, so that we can actually prescribe the right treatments to people.