But you already said that the second lactate peak wasn't seen in any other group, so I presume that doesn't happen in deconditioning.
As detailed in
this post, Vink observed both (1) high levels of lactate from trivial amounts of exercise; and (2) a second delayed peak in blood lactate appearing 30 minutes post-exercise.
I think the deconditioning issue is more of a confounding factor with (1), but not (2).
However, Vink says in his
paper that the timing of the arrival of the second delayed lactate peak can vary; it depends on whether you ate a meal just before the exercise. When you eat a main meal an hour before the exercise, Vink found the second delayed lactate peak appears 55 minutes post exercise. But if you ate your main meal 2 or more hours before the exercise, then the delayed lactate peak appears 30 minutes post exercise.
So it seems the more food in your stomach, the more the second lactate peak is delayed.
One evening I checked my lactate after exercise yet for some unknown reason the second peak of lactate in the blood, 30 minutes after exercise, didn’t happen. The strange thing was that my legs remained very painful and the 30% reduction in pain, which normally happens at the 30 minute mark didn’t happen either, and it took another 25 minutes before the noticeable 30% reduction in pain was there, this time at the 55 minute mark, whereby my lactate peaked at 9.4 mmol/l.
A few days later I checked my lactate after exercise again, which lasted about as long as the previous exercise, yet this time the lactate was only 8.1, and it was reached after 35 minutes instead of 55, again for no apparent reason, which obviously raised the question why was it not as usual at the 30 minutes mark and what is the main difference between the two episodes, responsible for this difference?
When the maximum lactate in the blood was reached after 55 minutes, I had my evening meal about one hour before the exercise and when it was reached after 35 minutes, I had it about 2 - 2 1/2 hours before the exercise.
Thinking about the issue of whether to use standardized exercises as per
@Hutan's suggestion, versus an ad hoc exercise or activity that the patient themselves chooses (one that they know from past experience causes a certain degree of exhaustion or PEM): I have just realized that the deconditioning factor comes into this:
If a patient chooses their own exercise that they know causes some exhaustion or PEM, but that they do regularly out of necessity (eg, vacuuming the carpet), then deconditioning is going to be less of an issue, because of the fact that they are regularly performing that exercise (and thus should have become conditioned to it to some degree).
But if a patient has to do some standardized strenuous exercise that they do not regularly do, then deconditioning is more likely to play a role. Just a thought.
I don't yet know the right way to conduct this study; like everybody, I am still thinking the issues through.