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.
Average Speed of Pitches. The speed of pitches depends greatly on the type of pitch that's thrown. According to measurements -- taken by eFastball's editor using a radar gun -- of pitches as they left the pitchers' hands, college and pro players' fastballs were typically thrown at an initial speed of 80 to 95 mph.