they are so thick honestly. It's cumulative... the activity threshold for triggering PEM is CUMULATIVE. He did a lot more phsycially so could so a lot less cognitively, it could easily have been demonstrated in the opposite way. Many adolescents have spontaneous recovery or it could have been a self limiting PVFS in the first place. They will insist on this post hoc ergo propter hoc assumption as if it were completely valid & foolproof.
But if some patient says they took a spoon full of apple cider vinegar every morning (or some other random thing) & recovered, they are assumed to be bonkers.
ETA: just to clarify - I not suggesting apple cider vinegar works as a 'cure' or that anecdotal reports of this should be regarded as anything more than anecdote, just that these BPS researchers use one rule for themselves & another for everyone else, & I recently heard the apple cider vinegar anecdote - it struck me as being as reliable as the above study.
I am glad the young man is feeling better though - but note he still needs home tuition