Posted by: O'Really () on Sat Feb 15 07:14:26 2003

The problem here may be Zig’s apparent inexperience with real world sporting activities. Specifically understanding the basics of motor control as applied to the swing itself. Combined with an over active imagination.

An attempt to respond to Zig’s laundry list on a point by point basis is as simple as saying that anyone who has even the rudimentary experience and understanding of motion analysis and physiology would understand that from THIS clip of McGuire it is virtually impossible to make the detailed analysis that Zig seems to THINK is possible. And for someone who allegedly works with 3 dimensional motion analysis I would have expected a greater appreciation for the difficulty presented even with the best motion capture information. That the McGuire clip, a single camera view, i.e. two dimensional images with horrible resolution is incapable of yielding the motion information to support Zig’s “analysis”.

I will also try to address what I consider the underlying fallacies in Zig's analysis.


“A loss of balance occurs when an individual no longer controls controls where they are in time or space with relationship to the ground or an object on which they are standing. This can occur in the swing when the weight is transferred to the front or back of the front foot or to the front or back of the rear foot.”


Zig also appears to have spent too much time studying postural control as applied to laboratory experiments/environments or working on fall prevention with aging populations. Two areas that are well behaved enough to lend themselves to clinical/academic attempts at defining stability. And Zig also appears to subscribe to the belief (folly?) that through the process of pure reductionism (if I analyze the pieces of the swing motion I can understand the whole swing). To put it bluntly "this time", there is no freaking way he (anyone) can tell from this (or for that matter ANY clip) that and I quote Zig,


“When Mark's back foot (heel) lifts of the ground nearly to the point when his on the tip of his toes he is off balance.”


The concept of dynamic balance is in reality a "figment" of the balance “imagination”. The term dynamic balance is in actuality a description of loss of balance.

The following is from Progress In Motor Control, Volume 2, Chapter entitled “Postural-Kinetic Capacity and Potential Function in Voluntary Movements” and I quote:


“Body Posture, Equilibrium, and Stability

According to mechanics, an equilibrium state can be stable or unstable: it is termed stable when the structure that is initially in equilibrium or a stationary state returns to its initial state after a perturbation. Hence, such states are dependent on the capacity to develop the forces necessary to oppose the perturbing forces: the greater the stability, the greater the forces able to perturb the initial state. Between its initial and final positions (i.e., between the onset and end of the motor act) the structure is in a state of transient “disequilibrium”, which is termed dynamic equilibrium.”


Balance is treated/viewed by clinicians as a “static” entity as applied to posture. The term dynamic balance is used to denote a state of “controlled loss of balance”, i.e. “disequilibrium”. And this disequilibrium is under the control of the motor program.

A further quote from the same Chapter:


“Postural Adjustments And Task Movement Parameters”

The primary result of these studies is that postural adjustments associated with voluntary movement proceed from an active , insofar as they result from muscular contractions, in addition to the passive articular forces that are transferred from one segment to another according to the action and reaction law. More precisely, these studies point to several general features:

1. Motor command is distributed to posture as well as to focal segments.

2. Postural function can be carried out by any muscle and is not limited to the muscles that are termed postural on the basis of fiber content.

3. Postural activities are organized according to a well defined sequence which is task-specific.

4. The muscle excitation can be either tonic or phasic, and postural fixation can be a dynamic process.

5. Postural muscular activities usually precede, accompany and follow the intentional movement.

Therefore, postural phenomena associated with voluntary movement are claimed to be under CNS control.”


The key here is that dynamic balance is a function of the intended movement goal.

To say that McGuire has lost his balance as he strides, something (striding a part of the swing sequence) he has done hundreds of thousands of times is to me ludicrous. And exhibits a naiveté of even a rudimentary understanding of not only the motor control process but also the swing process in general.

This is further indicated by the statement:


“Lower body stability can be affected by the strength and flexibility of the hamstrings and glutes. If the glutes or hamstrings are in a position where they are unlikely to complete a solid contraction (back leg bend or internal rotation of the back leg) the glutes and or hamstrings are unable to perform their job of stabilization of the body during the swing."

and

"When Mark's back foot (heel) lifts of the ground nearly to the point when his on the tip of his toes he is off balance.”


I have yet to see a ML hitter who has typically taken hundreds of thousands of swings, who loses his balance shifting his weight unless he is badly fooled on a pitch. The key word here is "control".

Again, we have a player, McGuire, who has swung a bat a zillion times during his 30+ years of baseball. I can reason (present and argument) that based on the principle of specificity to go along with his other strength/functional training that McGuire does not suffer from lower body instability due to lack of strength. Especially because there is absolutely no visible sign of instability other than what Zig “thinks” he sees.

As far as the general question of stability goes, instability typically manifests itself only if the player attempts to exceed the capabilities of the motor program. Only then "possibly" do flexibility, strength become issues.

Many 10 year olds can take swings with a very balanced lower body. It is only when that exceed their normal (learned motor program) such as over striding (over striding as defined by his loss of control) or make some other movement outside of his motor capabilities that balance and flexibility become issue. And more times than not the major reason for lack of balance is not due to strength and flexibility, its just the plain novelty (to the neural muscular system) of doing something beyond the normal swing (motor skill).

With respect to Zig’s detained descriptions of specific muscle activity, I can only say that I have never seen anyone with Zig’s "ad hoc” ability to analyze internal muscle actions and sequences to the detail presented from one McGuire swing clip of horrible quality. I rather suspect, based on what I said above, that being Zigs’s overall lack of knowledge and practical experience are a “play” (work?) here. As evidenced by motor concepts such as Bernstein’s degree’s of freedom problem (i.e. that there are an infinite number of muscles combination that can result in the same “outwards” actions) which makes it virtually impossible at best even using techniques such as EMG (direct measurement of muscle electrical activity) to predict what muscles are being used when.

Which leads me to the conclusion that based on Zig’s almost total lack of factual support (could not even produce or demonstrate his ‘perfect swing’ as in how do you know what a bad swing is until you can demonstrate a good swing) is nothing more than an emotional “out burst”. And has as much (less?) informational value as any other opinion presented in these forums.

As an aside (something else for poor Zig to ponder) based on the principle of individual differences can there ever be “one” perfect swing??

And I suggest that Zig start to take some of his own advice, that being:

“Please print this so you can read it two or three times.....

Thank you for showing that you can't see with your eyes what is really happening ……”


PS: To my knowledge there is no study on static/dynamic balance and swinging a baseball bat. But I did find a study on golfers that I thought might be of interest and relevant to this discussion.

“An Investigation Of Motor Control: The Static And Dynamic Balance Of Golfers
Stemm J, Green LB, Royer T: Tulane University, New Orleans, LA

The purpose of the study was to investigate the influence of motor control variables on the performance of golfers. This project is the first in an ongoing line of research composed of two phases, i.e., one involving the assessment of motor control variables, the second lending itself toward interventions for rehabilitation from injury and performance enhancement. This first investigation queried the relationship between measures of static and dynamic balance and three predetermined levels of golf handicaps. Fifty-two male subjects, aged 18-55, were divided into 3 groups according to handicaps (i.e., 0-9, 10-16, 17+) and were subjected to static and dynamic measures of balance using the "Balance Master", version 6.1 manufactured by Neurocom International, Inc. Subjects were required to undergo 10-second trials under the following conditions of static balance: (a) bilateral stance -eyes open (bso); (b) bilateral stance - eyes closed (bsc); (c) unilateral left stance -eyes open (uol); (d) unilateral left stance -eyes closed (ucl); (e) unilateral right stance -eyes open (uor); and (f) unilateral right stance - eyes closed (ucr). Dynamic balance was determined via a "limits of stability test" and "rhythmic weight shifts test" as measured by the "Balance Master" Neurocom International Inc. A one factor (golf handicap) analysis of variance was used to test for significant between group differences in postural sway velocity for double and single leg stance trials, and differences in sway velocity and directional control for medial-lateral and anterior-posterior rhythmic weight shift trials. A .05 level of significance was used for all statistical procedures. There were no significant between-group differences in any of the measures of static or dynamic balance. As a result, it was concluded that there is no significant difference in measures of fundamental balance between scratch golfers and high handicappers. However, given that balance, in and of itself, does not serve the purpose of explaining these differences, it does open the door for investigating other mediating variables, e.g., cognitive self-talk, biomechanical efficiency, levels of psychological trust.”