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.
There is a strong belief that throwing a baseball repeatedly at high rates of speed can help lead to arm injuries, yet the average velocity of pitches in baseball keeps rising every year. In 2008, the average four-seam fastball in Major League Baseball was 90.9 miles per hour, according to data on Fangraphs.com.