Fiber type changes

Watching Dr. Andy Galpin’s content recently gives me the impression that he believes that fiber type changes are only limited by time, as in if you had infinite time you could take someone from relatively slow twitch to extremely fast twitch with the right amount of time. Have i read into this correctly? or is there some truth to this which becomes irrelevant due to the amount of time required?

I don’t think that really happens based on present evidence, but I suppose if you eliminate the “human context” and have a theoretical muscle fiber that can last for a hundred years…maybe you can see some fast to slow (or reverse) fiber type switching.

That said, this is not what the current evidence reflects. Rather, there is a lot of fiber type switching within fast twitch and slow twitch muscle fibers due to training and environmental factors, but not from fast twitch to slow twitch. Within these domains there are fast twitch muscle fibers that function similarly to slow twitch and vice versa.