The arms should be "in the process of extending" as the bat nears contact with the ball. The arms should not be pushed or pulled in a straight line. And they shouldn't reach full extension before contact. You "let" the arms extend, which they want to do because of tangential forces taking them away from the body.
Likewise the bat is "in the process" of going around the hands, as the hands move. The bat should not be pushed at the ball. "Bat lag" is a position that can be seen in the swing, but it isn't a static position, it is a position that the bat moves through.
To get better bat acceleration you TRY to keep the arms bent and the hands close to the body, and take them around the body. This puts maximum tangential acceleration into the barrel. If you push the bat in a straight line, or pull it, you take away a lot of the tangential acceleration. You cannot push the barrel in a straight line, as fast as you can whip it by arcing the hands.
Extension is a follow through point. You don't extend before contact, you let the hands follow through and extend after contact.
Watch how Bonds' arms are bent at contact and they extend afterwards. Note how the top hand quickly goes in front of the bottom hand. The the barrel is whipping around his hands as his hands go around his body. There is no pull or push of the bat in a straight line.
If my 155 lb DD used the same body weight to bat weight ratio as your 70 lb DD using the 19 oz composite, she'd be swinging a 42 oz bat - OMG!
“It’s what you learn after you know it all that counts." -- Atributed to John Wooden by Mike Candrea
Ball at 55mph Kinetic energy of 9453
Bat at 45mph (a guess for a 9 yo) Kinetic energy of 16200
It takes kinetic energy value in the bat of about 3.5 to 4 times that of the ball, to avoid recoil. She doesn't even have 2 times the amount.
You can't swing a heavier bat faster than a light one, but if you can get a heavier bat to the ball, it helps stop the recoil. For each extra ounce of bat weight you lose ABOUT 2/3 of an mph.
The 19 oz bat at 43mph (2mph less) would provide 17565 kinetic energy. A bit more than the 16 oz, but still not enough to turn around a 55mph pitch.
I doubt that many 10u pitchers are throwing 55mph. I'd get her to work on whipping the barrel more, using the body more and use the 19oz bat.
Last edited by jbooth; 06-19-2012 at 07:16 PM.
Here are some vids of her in action on the field. Disregard my screaming wife I'm also throwing in a video of a nice slap. She just started slapping so that is still a work in progress.
Disregard screaming mom...lol
And here is the slap.
When I was 9 they didn't have metal. I swung a 30in 26oz. I couldn't get it around on 12 year-old 65mph, but at 9 I was in the minors and got it around just fine on 45 to 50mph pitchers.