thanks peckhammgatecrasher, I am from Pecknarm so I guess also a gate crasher too! I am keeping a diary of exertion and using pacing strategies at the moment but this looks like could be an aide to that, particularly interested to see how using phones camera for heart rate measurements works, that seems like a game changer. Without going into detail about my condition there are multiple ways the Long Covid Clinic insofar as it exists is failing, even given that there isn't a cure or proven remedies at this stage, so I will continue to plug away until I get a response if not a resolution. It might not sound like it but I am completely realistic about what can be done, but things are still falling far short of what can be reasonably be expected, even accepting the incredible burden the NHS is currently under. Thanks again for the link, could be really helpful and very kind of you!