Someone explain to me the obsession with "knee drive" for hitting

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Jul 28, 2020
17
3
Newbie here and posted in Coaching forum as well...

I'm hearing "knee drive" all over the place and I don't understand it.

I've taken a few competitive swings in my life and nothing about my swing can be explained with the words "knee drive"

Do I think "staying connected" is important? - Yes
Do I think the left hip opens and the right hip drives forward before contact(RH Hitter) - Yes
Do I think the back foot can become un-anchored? - Yes
Do I want the hands to get forward and make contact on the front side? - Yes

I would say "knee drive" may appear as a result or symptom of these other movements but I would never think of "knee drive" as a primary movement or swing thought. Educate me!
 
Last edited:
Nov 18, 2015
1,585
113
Perhaps it's meant in terms of a ground force reaction? How hard you push into the ground as part of a weight shift, vs just reaching with your front leg?
 
Jul 28, 2020
17
3
Where did you hear of this term....
I'm hearing it everywhere now... "knee drive" or "leg drive" from trainers and parents. So the concept is for a RH hitter that the right knee drives forward in the swing. I just don't think that way, if you are opening the left hip and driving the right hip the knee drives on its own, a symptom of what used to be called hip rotation.
 

rdbass

It wasn't me.
Jun 5, 2010
9,131
83
Not here.
Here is some info/explanation of the rear leg being the 'driver':
Gears.gif

The First Engine is the lower gear seen above. The First Engine is the rear leg. 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.

The rear leg is the driver of the swing, not the hips. The rear leg is loaded by the coil of the hip and the pulling back of the muscles of the back against the leg. A spiral-like load around the rear leg is created. Strong external rotation pressure will be felt by the rear foot at the ground. This pressure is caused by the coiling hip. It is not caused by any external rotation of the leg. In fact, this hip coiling action is countered by the leg's INTERNAL Rotation. A rag wring-like load is created in the rear hip socket. The hip is coiling rearward as the leg tries to turn forward. A bind is created. This means, the rear leg, while attempting to internally rotate actually has strong external rotation pressure applied to it because of the strength of the coiling hip. The rear hip coil is done by the rear hip socket coiling around the ball of the rear femur. The pelvis is a solid bone so the entire pelvis will pivot as this coiling occurs in the rear hip socket. However, the pivot point of the pelvis' turn is the rear hip socket. It is not the center of the pelvis which would happen if the hitter swung around a spinal axis.

As the hitter picks up his lead leg and starts to move out, his back muscles will begin to counter that forward momentum by pulling rearward in the same direction of the hip's coil. This action is shown well by this clip...
Pedroia1.gif

I call the above the 'Missing Frames'. Because they are missing in swings that are not high level. Most amateurs and many pros do not have the missing frames. But every great hitter has them.

Pedroia is using his back muscles to ARREST his forward momentum. That action creates a strong rubber band-like stretch around the leg. The rag wring-like stretch that was already established in his rear hip socket is enhanced by the muscles of the lower back and scap pulling rearward against his forward momentum. This action maintains the corner, around which the barrel is launched. Without this action the hitter would turn forward too soon and thereby bleed his stretch. Notice his center of gravity lowering. That happens as a result of the back working to arrest the momentum. The degree the center of gravity lower varies and it is mostly based on the hitters original stance and the amount of forward momentum he uses. But no matter, the hitters goal is to 'stay on the barstool'. Stay on his pedestal which is his rear leg. The hitter does not allow his weight to shift forward. The stretch is 'around' the rear leg and up the back to the scap. The front side has no involvement in this stretch process. Pedroia's lead leg extends forward involuntarily to maintain the body's balance. It moves much like your arms move when walking. You don't think about it. But they move on their own to provide balance. Front side involvement would require weight to be shifted forward. If weight is shifted there is no stretch around the rear leg. You can't have both. You can't have a quality rear hip/leg load and have weight forward. In order to get weight forward you MUST bleed any load you had in the rear leg.

When the above load is achieved, the hitter simply turns the barrel rearward and that triggers the leg to snap through the 'hold' of the hip and back and the barrel gets whipped forward with a quickness that no other technique can match.
 

rdbass

It wasn't me.
Jun 5, 2010
9,131
83
Not here.
Pujolsstretch.gif
BPoseyStretch.gif

Each of these hitters are pulling rearward with their back and scap against their forward move out. This action keeps their weight back and around their rear leg.
The significance of this load is the instant spring forward at go. You don't have to 'work' the launch. It's automatic. It leads to a true RELEASE of the barrel....not a swing of the barrel.

Next topic is How Do You Sync Your Two Engines.
If you want the second part let me know. If not that's okay.
 
Jul 28, 2020
17
3
rdbass - I have a firm understanding of your posts and probably should have labeled my post differently as "knee drive" . I get the balance and drive function of the legs. My issue is this, a lot instructors are saying "knee drive" and as i watch the videos above the knee (the knee, not the leg) "drives" forward as a result of clearing the left hip, not a conscious "drive" of the knee.

My question is this - which action do you think makes more sense teaching a hitter at that stage of the swing? "Drive the knee" or rotate the hips in order to coil and uncoil?

In my swing there is no doubt I'm thinking about rotating the hips to coil/uncoil, I guess my knee "drives" as well but that does not enter any swing thought that I have. Am I just thinking differently than everyone? I fear if I start saying "knee drive" I will have a bunch of girls bending their knee strangely while the rest of their swing falls apart.
 

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