Posted by: Mike Myers (mike.myers@bell.ca) on Tue May 4 13:41:59 2004

>>> Jack,
>
> You appear to suggest THT is dominant during the initial portion of the swing, but BHT becomes dominant toward the end of the swing.
>
> If you were to graph THT and BHT power components, would you observe initially high, but decreasing THT, and initially low, but increasing BHT throughout the swing?
>
> Regards,
> Mike. <<<
>
> Hi Mike
>
> Regardless of the swing mechanics a batter uses, there are two (and only two) forces acting on the bat (other than gravity) that can accelerate the bat-head around toward contact. One of these forces is directed down the ‘length’ of the bat. This force generates angular displacement of the bat when the path of the hands is also undergoing angular displacement (circular hand-path – Like swinging a ball around on a string).
>
> The second force a batter applies to the bat to generate bat speed is torque. Torque is applied when the hands apply opposing forces at the handle (‘across’ the length) of the bat. In other words, one hand is pulling back on the handle as the other is pushing in the opposite direction.
>
> In the swing of the top hitters, this push/pull action supplied through the hands (torque) is occurring constantly from pre-launch to contact. I defined the application of torque as Top-Hand-Torque and Bottom-Hand-Torque to identify the most active hand at that point of the swing. During pre-launch and initiation, the Top-hand is being pulled back around a slower moving bottom-hand (thus THT). As the bat approaches contact (or from the lag position), the bottom-hand is being pulled back around a slower moving top-hand (thus BHT).
>
> Mike, there is no break or timing of THT to BHT. Torque is constantly applied – the hands are always in a push/pull relationship -- only the terminology is changing.
>
> Jack Mankin
>
Jack,

Agreed - torque is constantly applied; 1.) CHP forces bat angular displacement and 2.) The hands are always in a push/pull relationship.

However, as you indicate:

"During pre-launch and initiation, the Top-hand is being pulled back around a slower moving bottom-hand (thus THT). As the bat approaches contact (or from the lag position), the bottom-hand is being pulled back around a slower moving top-hand (thus BHT)."

Does the relative speed of a hand to a fixed position on earth not indicate, in an absolute sense, which arm is supplying more torque power at each stage of the swing?

If legs and hips contribute only to CHP (equal to both hands by definition), and not THT or BHT, can we not infer:

1. When THT is dominant, the muscles of the lead arm (bicep) should be fairly relaxed (and stretched) - since the lead hand is moving slower relative to earth.

2. When BHT is dominant, the muscles of the lead arm are contracting, causing the lead arm to pull in toward the chest. This results in the lead hand moving faster relative to earth.

Regards,
Mike.