>>> I recently received The Final Arc and the heavy bag from Jack. I've decided that once my sons have their swing down consistently well that I will begin having them hit the bag fifty times from left and right handed to help develop those muscles involved in hitting. I've purchased my 11 yr. old a 34 oz. hickory bat. I have a ash bat coming for my 9 year old that's about 25 oz. Any one tried this, opinions? <<<
Very few hitters swing the bat enough to develop the strength and mechanics required to reach their potential at the plate. Therefore, I would agree that 50 to 100 swings a day hitting a heavy bag would be beneficial. However, I think many coaches (and dads) may not understand the proper role of the bag in forming sound rotational principles.
Brian, before setting up a program for your sons' work on the heavy bag, I would suggest you first study the material in the posts below I wrote on this topic. The first two posts explain why it is counterproductive for the student to attempt to 'drive through' or 'move' the bag. It further explains that since the bag absorbs the bat's momentum, it allows us to study the batter's contact form.
Confusion/heavy bag drill
I find the heavy bag very useful in helping linear students develop rotational mechanics. By "linear students," I am referring to those that have a tendency to use the extension of their arms to accelerate the forearms and hands ahead of shoulder rotation. We normally find that both their 'lead' and 'back' arms are approaching full extension at contact.
This is not what we find in batters with high level mechanics. As the two posts below (with video) show, once the back-elbow lowers to the side, both forearms and elbows remain in a fairly fixed position in relationship to the rotating body - lead-elbow remained at a constant angle - back-elbow remained back at the side (in the "L" position) to contact.
Role of the Lead-Arm
Role of the Back-Arm
When swinging at a heavy bag, the student can check his contact position - was he still driving the arms after contact - what was the position of his shoulders, forearms and elbows at contact - etc, etc.