Is it possible to reverse fiber adaptation?

This is sort of what I’m up against right now as I’m back into sprinting at age 32. I have used the search function but couldn’t really find what I wanted, so I’ll just ask. I believe I have always been more inclined toward sprinting/jumping activities since I was younger but I never really fully developed by ability. I mentioned to DanielC101, who posts here a lot, that my first and only 55m dash, with no training at all was 6.69 seconds, I had a long jump of over 22 feet and my vertical jump was 36 inches. I also did well in olympic style weightlifting.

Now, during a period after high school and early college, I stopped all explosive athletic activity and began long, slow distance running, including several 5k,10k races, which I carried on for a few years before just dropping running all together and doing nothing for a few years.

During the several years of long, slow runs, is it possible that I converted my faster fibers over to slow fibers, or at least de-activated them by causing them to function as slower twitch? If so, is it reversable, or would it be possible to ever really be able to not only get back to my previous “fast twitch levels” but to improve them? Is it just a matter of re-training them?

In the meantime, I’m doing gpp now, which is including many 100m reps; I’m also power cleaning like a madman.

I’m pretty sure that your body will adapt to the demands placed on it. I believe that fibers will convert to fast or slow twitch based on the activity.

You can definitely bring them back but yeah that LSD will do a number on you if you do enough of it. I took up triathlon type training for a while in my early 20’s and went from a 36 to about a 12 inch vertical and god knows how slow I was.

Gave all that crap up after a year or so and came back and hit a 42 inch vertical sub 4.3 fourty yard dash by the age of 25.