Originally Posted by LeeD
While having some lats is good (I"m a long time big wave surfer going out in places with the hardest paddleouts), I don't see the connection between lats and a service motion.
People think of the lats mostly when it comes to pull ups.
The lat is connected to the front of the upper arm at the humerus. The pec is also attached there. When both the lat and pec have been stretched by the earlier 'kinetic chain' motions such as the leg thrust they are capable of shortening very rapidly. With the arm and shoulder blade raised high as in the service motion when the lat and pec shorten it causes the arm to rotated around its axis by internal shoulder rotation.