From XKCD's 'what if', as part of an answer to the question "How high can a human throw something?";
Throwing is hard. In order to deliver a baseball to a batter, a pitcher has to release the ball at exactly the right point in the throw. A timing error of half a millisecond in either direction is enough to cause the ball to miss the strike zone. To put that in perspective, it takes about five milliseconds for the fastest nerve impulse to travel the length of the arm. That means that when your arm is still rotating toward the correct position, the signal to release the ball is already at your wrist. In terms of timing, this is like a drummer dropping a drumstick from the 10th story and hitting a drum on the ground on the correct beat.
You should read the whole answer (actually, you should follow the blog, assuming you already know about the XKCD comic and follow that already.) But for a nice illustration of what we take for granted, here's a lovely video;