"No reason to use a 11.5 oz racket when the incoming balls are not WTA level, as the WTA PROS use 11.5 oz rackets. The balls she sees are much slower, so maybe a 10 oz racket is plenty heavy, and it would aid her swingspeed even when forced to run and stretch"
My daughter is 12 yrs. old and I'm very cautious. She uses the Pure Drive Lite (10.3 oz. strung weight) (same racquet as Radwanska) which is very much on the light end of the spectrum. I'm very cautious with the racquet and strings (Wilson NXT control 16) as I want to be careful as her body is developing and, we are more focused on control and placement than power at this point. I'm sure we are robbing her of power but she is consistent and she has never had an injury.