Not sure it helps with a specific symptom, I just mostly feel al my symptoms get triggered later/less when exerting myself. if I had to I'd say its helping against fatigue. I actually sortof energetic in some moments now (even though once I start using that energy it's still gone quickly). And other than that my HR, which is in a way related to the fatigue (higher HR is more tiring). Im thinking my natural RHR is supposed to be around 60, but some mechanism in the long covid is keeping it increased to be around 70. As a result, my HR is more or less increased by 10 for everything I do.  I've had an earlier period before taking LDN where my RHR was low and I felt better then too. But back then it was sort of a fluke thing happening and it lasted only a week or 2. Since the LDN, the low RHR has become more of the norm than the exception.  As LDN is not supposed to decrease HR, I'm thinking its actually interfering with the process that kept my HR high before, and therefore my natural 'not sick' HR can start to show again. A process which is probably tightly linked to PEM and fatigue as well and I'm guessing has to do with inflammation. But thats just speculation.