Posted by: Jack Mankin (MrBatspeed@aol.com) on Thu Jan 5 16:02:21 2006

>>> This is an excellent point JAck. Problem with measuring time of swing is that it is hard to define launch with a low enough error.

As for length of path, Jack describes what I consider to tbe the optimum belly-up/quick type swing and he has measured how far the hands go as a way of demonstrating how short this is.

JAck,given a good high level hitter, have you measured the handpath in in vs out swings and compared them ?

The outsdie swing has a longer swing radius, but the high load sucks the momentum out of the torso faster so the torso does not turn much.

On the insdie,the BHT/pull has a very short/low load swing radius, but the torso turns much more, ?then dcelerates right at contact due to "hook effect".

This means that handpath is one thing and bathead path another and difficult to measure length/spatial aspect of swing as well again related to difficulty identiofying a "launch" point. <<<

Hi Tom

I agree one cannot get real accurate measurements of time through video analysis. As an example: When viewing a swing at 30 fps, the shudder speed may be set at 1/60 second. This means we would only see ½ of the movement that occurred in that frame. According to when the shudder was opened or closed, we may get close to a ½ frame difference of the same movement from one swing to the next.

I found this to be a real problem when studying wrist binds and the bat’s reaction to them. The buildup of pressure on the wrist causes it to flip over extremely fast – perhaps 1/100 of a second. Therefore, I may see it occur in one swing when the shudder was open but not in the next swing.

You stated:
>>> , “JAck,given a good high level hitter, have you measured the handpath in in vs out swings and compared them ?

The outsdie swing has a longer swing radius, but the high load sucks the momentum out of the torso faster so the torso does not turn much.

On the insdie,the BHT/pull has a very short/low load swing radius, but the torso turns much more, ?then dcelerates right at contact due to "hook effect".

This means that handpath is one thing and bathead path another and difficult to measure length/spatial aspect of swing as well again related to difficulty identiofying a "launch" point. <<<

Although there can be bat and arm trajectories during pre-launch, I have always defined “launch” as when shoulder rotation is initiated. I found that in high-level swings, the number of frames from launch to contact was about the same for both inside and outside pitches – about 4 to 4 ½ frames at 30 fps (8 to 9 frames at 60 fps).

While working with a motion studies computer we found that although the radius of the hand and bat-head path was greater on outside pitches, in most cases the distance the bat-head traveled to contact to be about the same on both. – On inside pitches the bat rotated farther (well pasted perpendicular to the pull position) – On outside pitches the bat rotated less (straight away or to the opposite field), but the bat-head traveled about the same distance for both.

Jack Mankin