Movement and use of the back leg
Caution this is technical, but hopefully it will explain how the back leg works in a swing.
The summary is that the back leg simultaneously abducts and externally rotates in high level swings.
It's what I call "moving the magic spot", and "using the butt muscles."
Move Magic Spot
If you use the muscles as is shown in the video above, it will look like this;
Last edited by jbooth; 06-23-2012 at 06:43 PM.
For those of you who are having reservations, this is actually a really well put together video. And, it's going to tick off the IR-IR-IR believers.
Yes, because they don't understand physics. They see the back leg/knee internally rotate and adduct and they erroneously conclude that the adductor muscles are making that happen.Originally Posted by pstein
When the leg is not bearing any weight and you want to internally rotate it and adduct it, the adductor muscles will do that. But, when you weight your back leg those muscles can't move the leg in that direction.
The internal rotation and adduction of the back leg occurs AFTER the weight is shifted to the front leg and the rotation of the pelvis pulls the weight off of the back leg. The IR and adduction is simply a follow through action. It is not an action that applies any force to cause shift and rotation of the torso.
Some ignorant person viewed the leg action: looked online to find the muscles that make that action, and found the adductors, but failed to understand Newton's Law of equal and opposite reaction. The adductors can't adduct the leg when weight is on it. You have to get the weight off of it first, by abducting it.
That is why squishing the but is not a good thing, if you're trying to turn the leg to get power. You have to unweight the heel to squish, and then all you do is internally rotate the leg. That does nothing to shift and rotate the torso.
Last edited by jbooth; 06-23-2012 at 08:15 PM.
Thanks for a great video....it helps us uneducated coaches understand the bio mechaincs of how the back leg works. This turned the light bulb on for me. Now I understand why the elvis move should not be taught. thanks again
jbooth, is there any harm in performing this movement while in the stance...before you lift your front foot to stride? I have my daughter get in the box and perform this movement before the pitcher begins her delivery. All she has to do is lift her front foot and she immediately moves forward while keeping her hips coiled. I guess what FiveFrameSwing would call using the Move to Forward-by-Coil??? Don't know if that is the most efficient way to get there, but it seems to work for her. I usually see the movements you are describing after the hitter lifts their front foot, just wondering if I'm hurting her by having her perform the move prior to lifting the front foot. Thanks for all the great information.
Great video, but I think someone doesn't understand the Elvis Move. Here is a partial post. the female the knee starting towards where the second baseman normally plays ( as a RH and shortstop for LH ) is important due to the increased width of the hip and width between the legs being wider. The knee cap is a good indicator of this.
Note: You can test for this your self by placing your back hand on a wall to brace your self so you can lift your back leg off the ground and take the knee towards the second baseman's normal playing position. Then repeat and point the knee towards the pitchers position. General guide line is if the thighs touch on the female you have lost your power.
Males having a smaller hip width and are width between the hips is narrower which allows the knee to be more under them. See Bonds above and then how the young lady has her knee go forward before it goes under.
Many Asian girls in general in my opinion have less hip width such as Jen Yee and can bring it more under them.
Also as you begin to do the Elvis move keep the front knee soft or flexed.
Thinking slow to load and soft to step on a flexed front knee helps.
Some hitters lock it out too soon and that can effect bat on ball location. Do it in front of a mirror and if you lock it up too soon you will see your head/ body get taller. Driving with the back knee at just the right moment is the art of hitting with power in my opinion. Softer is better than locked out.
I posted about using a Milk Crate as a tool. Notice her back leg would hit the foam on the milk crate.
http://www.golfsmith.com/product/300...lz-power-wedge We have also used this with young kids to get them to hear and feel it. Also watch her back hip go Linear. Focus on fence behind her. Take a bat on those that don't squish the bug put it up against the back hip and see the gap created. Those that like to say the swing is pure rotational? Rest my case.
Last edited by SBFAMILY; 06-25-2012 at 04:37 PM.
The knee joint has nothing whatsoever to do with creating force or power. The knee must stay bent in order to allow rotation without head movement. In the action that I described the medial (inner) side of the knee will move toward the front foot. Then, as the pelvic bone begins to rotate, the anterior (front) part of the knee will move toward the 2B position (for RH), then the back heel comes up as weight gets on the front foot, and then the back foot pivots and the anterior (front) of the knee will swing in and be facing the pitcher.
Like this;
The abduction of the femur causes the knee to move toward the front foot, the external rotation moves the knee out, then, when weight starts to come off of the back foot, the femur adducts and internally rotates, which swings the knee back inward. The adduction and internal rotation is not providing the force to rotate. The weight is already shifted and rotation is in process when that occurs.
The front leg does not straighten because of pull back of the hip. The back knee is pulled forward as the back hip is pushed then pulled. The front leg is absorbing 1.2 times the body weight and pressure to prevent lunging is pushing the front femur against the front hip socket. This pushes the front hip out and back.
The only way that the front leg could be pulled straight is if all of your weight was on the back foot when the hips were still closed. The weight is on the front foot as the hips finish their rotation, so it defies the laws of physics, to say the leg is pulled straight. The front leg blocks the forward momentum and pushes back. It doesn't get pulled back.
Last edited by jbooth; 06-25-2012 at 05:00 PM.
The girl in the clip was taught for several years to lift her back heel when she dropped her front heel.
In this clip she is NOT doing that action and she is NOT actively turning her back knee down-and-in. She is actually doing what I call the "anti-Elvis" move. The sooner you realize that the back knee turning down-and-in or the back heel coming off the ground, is an effect and not a cause, the sooner you will get your kid weight shifting better.
"Cause and effect refers to the philosophical concept of causality, in which an action or event will produce a certain response to the action in the form of another event."
The teachable action or event that the girl in this demo video is performing is: turning her hips back and then turning them forward using her butt muscles, while making sure she doesn't turn her back leg inwards. She is attempting to get a better feel of her hips going towards the ball while her back foot is wanting to go in the opposite direction. She is attempting to get a better feel of deepening pressure at her back foot at the moment of transition when her hips begin to turn towards the ball.
She is attempting to duplicate this action, minus the slippage:
She is attempting to do exactly what Sevam1 explains in this video:
I've taught weight shift both ways. Your kid will unquestionably weight shift better if they turn their hips back and then forward while holding onto the pressure at the back foot as described by Sevam1.
jbooth does an excellent job of explaining how the body creates the pressure at the back foot, and how the body uses that pressure to launch the hips.
Who here is talking about the swing as being purely rotational? I have multiple post on this board talking about the importance of letting the head come forward to maintain balance when the front foot is lifted to cock the hips.
Driving with the back knee actually leaks the coil and reduces power. The back knee moving down-and-in is an EFFECT not a CAUSE. I taught it backwards for years, and kids will get a much better weight shift if they are taught to launch their hips off of a firm rear leg, rather than to try and drive their hips forward by actively driving with their back knee.
He's trying to describe in laymen's terms what I described in technical terms in the video that I posted to start this thread.
The girl in the clip was taught for several years to lift her back heel when she dropped her front heel.
In this clip she is NOT doing that action and she is NOT actively turning her back knee down-and-in. She is actually doing what I call the "anti-Elvis" move. The sooner you realize that the back knee turning down-and-in or the back heel coming off the ground, is an effect and not a cause, the sooner you will get your kid weight shifting better.
"Cause and effect refers to the philosophical concept of causality, in which an action or event will produce a certain response to the action in the form of another event."
The teachable action or event that the girl in this demo video is performing is: turning her hips back and then turning them forward using her butt muscles, while making sure she doesn't turn her back leg inwards. She is attempting to get a better feel of her hips going towards the ball while her back foot is wanting to go in the opposite direction. She is attempting to get a better feel of deepening pressure at her back foot at the moment of transition when her hips begin to turn towards the ball.
She is attempting to duplicate this action, minus the slippage:
She is attempting to do exactly what Sevam1 explains in this video:
I've taught weight shift both ways. Your kid will unquestionably weight shift better if they turn their hips back and then forward while holding onto the pressure at the back foot as described by Sevam1.
jbooth does an excellent job of explaining how the body creates the pressure at the back foot, and how the body uses that pressure to launch the hips.
You may feel your back foot wanting to twist, but not necessarily. If you hold the back heel down and use the butt muscles, the brain/body executes what I showed and what he is saying, but you don't necessarily have to think of twisting the foot outward. The muscles in the lower leg and foot are doing very little to make you shift and rotate. You feel the foot against the ground because the entire leg is being twisted out (externally rotated) by the muscles in your butt.
What he is essentially saying as far as it relates to this forum and the baseball swing, is; "don't squish the bug." Don't internally rotate on back foot.
SBFAMILY (06-26-2012)
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