Working my way through the article, it is definitely in the “hard” category.
Page # 7:
Indeed, Almeida-Silveira and associates found both decreased slow twitch fibre percentage and decreased H-reflex amplitude as a result of a plyometric training intervention.
I have not had time to track down and read the supporting articles BUT the implication is that some of the slow twitch fibres have changed (just applying logic since if the percentage decreases and they do not disappear, they must be changed to something else).
Is this an accurate assessment of the statement on my part? And if so, is this one of those times when there is conflicting information…I have/had been taught that is was not possible to substantially change the percentages of slow and fast twitch fibres a person has; not that the cross sectional areas of the fibres can not be changed but that, as the quote implies, the percentages remain more or less fixed.