smaller 13 yr old swing

[Tango]

"The left leg extended at the
knee, pushing the left hip backward,
while the right leg pushed the right
hip forward"

Excerpt from the Hitting a Baseball: A Biomechanical Description paper RDB posted.

I think it's more of a snap back with front hip that straightens the leg.

 

[rdbass]

"The left leg extended at the
knee, pushing the left hip backward,
while the right leg pushed the right
hip forward"

Excerpt from the Hitting a Baseball: A Biomechanical Description paper RDB posted.

I posted the paper to provide the source of where I got this information from:

Nearing the point of impact, the
hitter utilized the last bit of angular
speed and kinetic link as the speed
of bat lag or uncocking reached its
maximum value of 1588"/sec at 0.020
seconds before ball contact (Table 2,
Figure 3). The bat was then driven to
its maximum linear velocity of 31
m/sec in unison with the right arm
maximum extension velocity of 9487
sec, both occurring 0.015 seconds
before ball contact.
Ball Contact
At ball contact, the body had
used both coordination and position
to generate bat speed and direction.
The linear speed of the bat had decelerated
slightly to 29 m/sec, but
the most significant component of
that speed was directed in the positive
X direction toward the ball.

As far as this:

"The left leg extended at the
knee, pushing the left hip backward,
while the right leg pushed the right
hip forward"

I don't believe it's saying that the front leg actively 'pushes' the left hip backward. I read it as a result of the extension of the leg causing the push back of the front hip. I don't believe the front leg actively pushes the front hip backward but, blocks as the rear hip eventually goes forward.

 

[ian]

I think it's more of a snap back with front hip that straightens the leg.

You could be right. The study says otherwise. Read the 'foot contact' section and it might change your mind.

With the weight shift forward and
the shear force applied in the X and
Y direction by both the left and right
foot, segments were now accelerated
to maximum velocities a. the body
coordinated an effort to produce bat
speed. The left leg extended at the
knee, pushing the left hip backward,
while the right leg pushed the right
hip forward, creating a counterclock-
wise acceleration of the hips around
the axis of the trunk. The rotational
velocity of the hips increased until it
reached a maximum of 714"/sec,
0.075 seconds prior to ball contact.
The shoulders and arms, following
the lead of the hips, accelerated to a
maximum rotational velocity of 937"/
sec and 1 160°/sec, respectively, 0.065
seconds prior to ball contact.
As a result of the body's coordi-
nation, the bat also moved around
the axis of the trunk, increasing in
both angular velocity and linear ve-
locity.

 

[rdbass]

That's a scientist description of what he/they think happens in the swing.
This is what I think happens:

I don't believe it's saying that the front leg actively 'pushes' the left hip backward. I read it as a result of the extension of the leg causing the push back of the front hip. I don't believe the front leg actively pushes the front hip backward but, blocks as the rear hip eventually goes forward.

I'm going to 'parrot' again:

Be careful who you listen to. Be careful of those who use textbooks and make false claims. Be extra careful of scientists who try to big dog you with Anatomy and Physiology terminology. Be careful of Kinesiologists who say 'the body doesn't work like that'. Um....my body does. So did Barry's. Manny's. Ted's. Mickey's. The body works in many different ways. Science explains EVERYONE'S swing. The good ones. And the bad ones. I have yet to find a scientist who can explain the high level swing properly. And we won't find one until one of them can swing in the high level pattern

High level hitters are one-legged, meaning the vast majority of their weight is in/over their rear leg AT LAUNCH. Their lead leg is on the ground. It supplies balance. But it has no significant weight on it at launch. It has no real function in the swing other than to 'catch' the swing so you don't fall over as a result of the momentum created. In the act of 'catching' the swing, the lead leg will provide a 'block' so that the energy created continues around the rear leg and into contact rather than bleeding forward linearly. But it does not actively push back. It blocks

 

[Greenmonsters]

Didn't the Zepp data show that the bat slightly decelerated before contact with the ball.
Some may like this, some may not:
Hitting a baseball: A Biomechanical Description:
https://www.gettingallofit.com/images/PAPER--Hitting A Baseball - A Biomechanical Description.pdf

Haven't read the article thoroughly yet, but FWIW I see that it was published in 1995 (which means it probably was researched and written in the early 1990s, which means before the widespread availability and use of high frame rate slo mo video) and considers the spine as the axis of rotation (which I believe most would equate with a two-legged swing).

Just something to think about

 

[rdbass]

Again I posted the source of where I got this info from:

At ball contact, the body had
used both coordination and position
to generate bat speed and direction.
The linear speed of the bat had decelerated
slightly to 29 m/sec, but

 

[ian]

I posted the paper to provide the source of where I got this information from:

As far as this:

I don't believe it's saying that the front leg actively 'pushes' the left hip backward. I read it as a result of the extension of the leg causing the push back of the front hip. I don't believe the front leg actively pushes the front hip backward but, blocks as the rear hip eventually goes forward.

Thanks for the link RDB.

There is a difference between at contact and .015 seconds before contact. Noteworthy since MLB player time to contact is like .130 seconds.

"With the weight shift forward and
the shear force applied in the X and
Y direction by both the left and right
foot, segments were now accelerated
to maximum velocities a. the body
coordinated an effort to produce bat
speed"

What is your interpretation of this?

 

[ian]

Haven't read the article thoroughly yet, but FWIW I see that it was published in 1995 (which means it probably was researched and written in the early 1990s, which means before the widespread availability and use of high frame rate slo mo video) and considers the spine as the axis of rotation (which I believe most would equate with a two-legged swing).

Just something to think about

Science deny-er! Science deny-er! GM is a science deny-er! You probably dont think the earth is warming or ummm cooling or whatever because the data is old.

 

[ian]

Again I posted the source of where I got this info from:

Thats good info. It lets me know the guy should have started his swing .015 later. Then he would have hit the ball at the best possible point in his swing.

 

[ian]

That's a scientist description of what he/they think happens in the swing.
This is what I think happens:

I'm going to 'parrot' again:

Shhhhhhoooot. RDB you know I dont trust those damn lab coats either.