Medical Definition of Z LINE. : any of the dark bands across a striated muscle fiber that mark the junction of actin filaments in adjacent sarcomeres.Britannica.com: Encyclopedia article about Z line.efinition of Z LINE. : any of the dark thin bands across a striated muscle fiber that mark the junction of actin filaments in adjacent sarcomeres. ADVERTISEMENT.
The average fb speed in the MLB is 91-92ish. Catchers compete with this when trying to throw down a runner at 90ish. The average throw speed from third base is 80 MPH. As for the rest of the positions I am not sure of the exact average, but it is not as fast or faster than pitch speed.
I think Billy Hamilton of the Reds is generally acclaimed as the fastest man in baseball at the moment. The Marlins' Dee Gordon and the Royals' Jarrod Dyson and Terrance Gore (currently in the minors) are also in the running. Video: Hamilton scores on sac fly. Plenty more videos of Hamilton here.