Posted by: Jack Mankin (MrBatspeed@aol.com) on Wed May 2 02:36:57 2001

Question/Comment:

>>> You asked: "I have often pondered why it would be more efficient to push off with the back leg and slide the hips forward and then convert some of that momentum into hip rotation. Why is that more efficient than just using the push off to turn the hips from the get-go."
my response - an analogy - why does a high jumper (or basketball player) run forward to jump higher? Why not just bend the knees and jump straight up? How can running forward add to vertical leap? In fact it is harder to bend the knees as much from a run, so it should result in less vertical leap. But it does not. The running start is energy in the system. It can be redirected/converted. If it is directed upwards, there is more energy for a running leap than for a standing leap, therefore you can jump higher with a running start.
The hip slide (stride or no stride) is the runnning start. The front leg redirecting the energy is the same as the jumper's jump - both convert linear momentum into something else. The jumper redirects it in another linear direction, the hitter redirects it into rotational/angular momentum.
The hip slide/weight shift happens before the torquing pushes that turn the hips. The sequence of hip slide then hip torque is more powerful than just hip torque with the legs.
A player with very strong legs and explosive quickness in those legs can probably generate more than enough energy to transfer to the bat to hit the ball very far, but not as easily.
An additional consideration- the body has its own properties. Elasticity of muscles, tendons, ligaments, etc. plays a role in hitting. The plyometric response ('stretch, then contract' gives a greater contraction than just 'contract') is a significant contributor here. Simply pushing with the front leg is not as strong as loading the front leg, then pushing the load back. It is the equivalent of jumping from a static knee bend vs. the usual quick bend the knees and jump that we all do.
If you take the exceptionally strong legged man and have them hit starting from a statically bent front knee and then from a flex-then-straighten front knee, the latter will produce more power, due to the plyometric response.
In fact, the latter movement is best accomplished by sliding the hips forward to put weight on the front leg, then pushing back with the front leg quads. This internal weight shift loads the front leg with a window of about .5 seconds response time (use it within .5 or start losing it). This is the imprecise timing needed to time a pitch from the lower body perspective.
This line of thought questions what is meant by ‘balance’ or ‘full balance’. If balance means coming to a complete stop and the body’s system giving up its energy, then all that motion is in vain/wasted. I doubt that a Griffey or Bonds is that inefficient. I suspect that in that ‘balance’ is a dynamic state where large muscles are being deeply loaded in order to unload more forcefully. The ‘delay’ is both the timing window and internal body workings to best redirect the built-up energy into rotation.
I have questions about what many consider balance and would be interested in responses concerning whether it is considered dynamic or static and the consequences of each.

Two main issues here:
Conversion of linear(weight shift) momentum to angular momentum helps power the hip turn that feeds the transfer mechanics that rotate the shoulders to develop batspeed. This was the big issue of debate in April. Any more thoughts?

Coming to balance after weight shift - is this a static stop or a dynamic moment that the hitter passes through as he goes from weight shift to conversion to rotational/angular momentum.
Any thoughts on this? <<<

Jack Mankin's reply:

Hi Major Dan

What some consider weight shift has really undergone some major changes over the years. Professor Adair and other noted authorities believed that the forward movement of the body developed energy that could be converted into bat speed. In Adair’s model, he claimed a 185 lb hitter moving forward 18 inches at 7 or 8 mph during the swing would generated sufficient kinetic energy that when the forward motion of the hands slowed to a near stop, the bat would be accelerated from around 40 mph to around 75 mph.

Without going into detail, we how know that the conclusions drawn from that model were incorrect. But at least Professor Adair showed he understood the basic laws of the “conservation of energy.” He understood that for an action to generate energy that could cause an appreciable acceleration of the bat, an equal or greater amount (loss to friction and etc) of energy must be added to the system. -- Energy in = Energy out – Small energy in = Small energy out. This is why Adair could not accept the stationary axis model. For his model to work there must be a substantial movement of the axis during the swing.

There seems to be such a need in some people to keep the weight shift theory alive that they seemed to have lost all sense of proportion. I think we could all agree that a player running at full stride could use that momentum to leap higher. But also consider the amount of added energy expended to gain those added inches. I fail to see how we can compare that action to a 4 or 5 inch slide of the hips in the baseball swing. From a short or no-stride stance, it requires very very little energy to let the hips slide forward a few inches before rotation. Why would we then think that when the slide stops there is this tremendous stored up energy released for the rotation. --- I’m sorry Major Dan but I just don’t buy it.

Jack Mankin