Myosin heavy chain molecular weight is measured using gel electrophoresis to differentiate between fast-twitch and slow-twitch muscle fibers.

“so if you were to use a technique that we use called gel electropheresis basically you put a gel between two pieces of glass and you just pour gel in there and it gets like solidified just like hair gel like a little bit thicker and then you put each individual muscle fiber in its own vertical lane and then you put a little bit of positive charge on the top end a little bit of negative charge in the bottom end or inverse doesn't matter and then you actually put a little bit of chemical bath around the muscle fiber that has a charge you turn the electricity on positive goes to negative Etc and so those fibers run down vertically through the Gill we hit stop at a certain time point and the smaller ones have gone further because smaller molecular will go through the gel faster and so we stop basically put it we develop it like you would develop a picture like like old school photography stuff literally the same silver nitrate ET that you use and we can see the ones that have gone further down are slow twitch the ones that want stay up higher are fast twitch”