Balk rule interpretation

Question
Left handed pitcher, runner on first:  After the pitcher comes to a set position he lifts his right leg (non-pivot) straight up with knee and foot pointed toward first base (the foot never goes past the pitching rubber).  Can the pitcher hold that position if he remains motionless (balanced) to "freeze" the runner, then deliver to home or to first base?  In other words, his motion does not have to be a "continuous" motion to either home or first, correct?  I have a young pitcher that is a former gymnast, and has incredible balance and uses this "pause" to hold runners and I want to make sure it is legal, which I believe to be true.  

Thank you.

Answer
Thanks for the question....If I am working the game, I woulod certainly call a balk.  There is no pause or hesitation allowed whatsoever....You may periodically get away w/ it, but not from a good trained unpire......

But hewy, If I am the coach, I will milk it for all it's worth until an ump calls me on it too....lol.  Have for over 20 years.  But then when it is called, you will not be surprised.....

Good luck.....Andy