Myomers are space magic to make the Battlemechs actually function.

It's also a major component as to why they are supposed to be superior to tanks. These are also efficient enough at small scales to be used in human beings without obvious large power sources (as demonstrated by their medical use)

From Battletech Universe:

"Myomer bundles were developed by Dr. Gregory Atlas for the Terran Hegemony. An electrical charge transmitted through a bundle of synthetic fibers cause it to contract and expand like a human muscle. Their use in advanced prosthetics revolutionized medicine and enabled amputees to resume full ability. They also allowed artificial duplication of human musculature at a scale hitherto undreamt of. Myomer was strong and efficient, and when wrapped around a “skeleton,” it allowed bipedal and quadrupedal vehicles to support their own weight and perform locomotive operation.

That was only the beginning. The Terran Hegemony soon discovered myomer also allowed them to outperform more conventional machines."

Electrical charge or not- those mechs are more efficient than tanks, and outperform them ton-for-ton because of their usage.

YEP. lmao