Someone who "throws like a girl" probably just has bad
footwork.
As
Lord Brawl noted previously in this node, in the act of throwing an object, one generates
power from the
shoulder,
abdominal and
leg muscles; one uses the
elbow and the
wrist for
accuracy.
This is all understandably
counter-intuitive for a
novice; throwing seems like something one does with the arm, but if you don't use the rest of your body, your throw will have little
distance.
In a proper throwing motion, one should step forward with the opposite foot just after
cocking the arm. While doing this, the thrower should twist
his/her torso a bit toward the throwing arm. Then, in the process of throwing the object, the person will naturally transfer his/her weight to the forward (opposite) foot during the forward throwing
motion and twist his/her body from right to left (for a
right-hander) during the follow-through. All this will add power.
Unfortunately, many people who haven't been taught how to throw properly try copying their peers and end up stepping forward with the
incorrect foot — i.e., the right foot for a right-handed person. This will
definitely make you throw poorly and will look like a total
dork as well. I'd guess this is the real
genesis of the "throws like a girl" insult.