Myofibrilin

From Memory Alpha, the free Star Trek reference.

Myofibrilin was a biochemical compound prescribed for extended zero gravity missions. The invention of artificial gravity cause myofibrilin to fall out of use by 2155 except for during certain military exercises, and for workers in remote places where artificial gravity was impractical; places such as the lunar mining colonies, including the Orpheus Mining Colony. (ENT: "Demons")