I think the patient's severity of ME/CFS (mild, moderate or severe) needs to be noted in the results, but I think this test should be open to all severity levels. The intensity of exercise needed to trigger a bit of PEM would be different for each patient though.
For very severe patients like Mark Vink, it was just the 5 or 6 yard walk to his bathroom. For a moderate patient, some PEM may be triggered from a 10 minute walk.
ME/CFS patients are normally quite good at knowing what level of exercise will begin to trigger PEM. So each participant in our informal study would have to choose their own level of PEM-inducing exercise; they would need to do just enough exercise to trigger some PEM (but obviously you don't want to do too much and trigger a major crash).
I believe this sort of lactate testing normally uses a short bout (ie, one to two minutes) of intense exercise, and then measures the lactate levels in the minutes following this short bout.
So for a moderate patient, instead of a 10 minute walk, in order to "compress" their exercise into a short 2 minute intense bout, they may need to do two minutes of running, and then measure their lactate 5 minutes after this exercise, and then 30 minutes after this exercise.
For a severe patient, perhaps just walking up and down the stairs once or twice will be enough to trigger some PEM.
For a mild patient, it's possible that they would have to do very intense exercise for two minutes (like sprinting at absolute top speed) in order to trigger some PEM.
If we did replicate this (and even if we did not), I think we could then post up the results as an informal study in a PR forum thread, and then email a few ME/CFS researchers that are interested in the PEM and exercise aspects of ME/CFS. This may well help get more research done in this area.
What I am (optimistically) thinking is that if many ME/CFS patients exhibit this exaggerated production of lactate after a short bout of exercise, then ultimately this might become the basis of a useful diagnostic test for ME/CFS.
It would be much simpler and cheaper (and much less strenuous on the patient) than the 2-day CPET test. If it were viable, this lactate test could even be done in a primary care doctor's surgery: the doctor would simply ask a (say moderate) ME/CFS patient to jog on the spot for two minutes in the doctor's office, then measure their lactate level 5 and 30 minutes later. It could be a quick and easy diagnosis.
I don't think that is the case, unless patients are pushing themselves past their limits.