Posted by: O'Really () on Sun Feb 16 05:40:39 2003

Ooops, only part of what I wrote got posted. Here's the entire post.

One last “hurrah” on stability and those who profess to have a lot of scientific “answers” about how to swing a bat (including “yours truly”).


Relationship Between Static, Dynamic
And Functional Single Leg Postural
Control Performance
Riemann BL, Schmitz RJ, Jackson SA:
Applied Neuromechanics Research
Laboratory, University of North Carolina-
Greensboro, Greensboro, NC

Multiple postural assessment approaches have been developed and utilized secondary to examining different aspects of postural control. The purpose of this investigation was to determine if relationships in performance existed between six different tasks representing static, dynamic and functional postural control performance. Fiftyfour recreationally active participants (23 males, 31 females, age=21.9±3.4yrs, weight=69.2±12.9 kg, height=174.1±25.4 cm) attended one 25 minute testing session. In a counterbalanced order, each subject completed 6 single leg (dominant limb) postural control tasks: fixed surface/ eyes open (FIEO), fixed surface/eyes closed (FIEC), multiaxial surface/eyes open (MAEO), multiaxial surface/eyes closed (MAEC), star excursion balance test (STAR) and the single leg hop-stabilization test (SLHST). The fixed and multiaxial (Balance Board, Gordon, Inc.) surface tasks were conducted on a forceplate (Bertec, Inc.). During each trial, participants were asked to stand as motionless as possible in a standardized testing position. Force and moment outputs from the forceplate were used to calculate the average center of pressure velocity during the middle 5 seconds across three 7 second trials under each surface and visual condition. For the STAR, participants were required to maintain equilibrium on their dominant limb while extending their contralateral limb in 8 different directions. A grand average across 3 trials in each of the 8 directions was calculated and normalized to body height. The SLSHT required subjects to perform a series of targeted single leg hops while maintaining equilibrium. The total score (landing + balancing errors) was used to represent functional postural control performance. Pearson bivariate correlations were conducted between the six outcome variables (p<.05). Results of the analysis revealed a significant moderate correlations between FIEO and FIEC (r=.550, p<.001), FIEC and MAEC (r=.546, p<.001) and MAEO and MAEC (r=.559, p<.001) and significant weak correlations between FIEO and MAEO (r=.297, p=.038) and FIEO and MAEC (r=.474, p<.001). The results of this investigation suggest while performance of stabilization tasks on either firm or multiaxial surfaces is related, they are unrelated to postural control performance during voluntary reaching and hopping movements. Inherently important is the lack of any significant relationships between any of the tasks with the functional performance task (SLHST). Clinically these results support the utilization of a battery of tasks to determine overall postural control performance. Future research should be directed towards identifying which aspect of the postural control system each tasks optimally targets. S-77 Journal of Athletic Training”


For those who have little or no “stomach” for the science. Or now have science “jitters” and uncertainty due to either my or Zig’s posts, the importance of this study is (to me) in these statements:

“The results of this investigation suggest while performance of stabilization tasks on either firm or multiaxial surfaces is related, they are unrelated to postural control performance during voluntary reaching and hopping movements. Inherently important is the lack of any significant relationships between any of the tasks with the functional performance task (SLHST). Clinically these results support the utilization of a battery of tasks to determine overall postural control performance. Future research should be directed towards identifying which aspect of the postural control system each tasks optimally targets. S-77 Journal of Athletic Training”


Which says (based on this and other research studies) that posture/stability training AND measurement are specific to the task at hand. In other words training to improve you balance on an unstable surface (all balance training that is not task specific?) most likely will not improve your ability to swing a baseball bat on a stable surface. And it is highly questionable that it would help swinging a bat on an unstable surface.

And as important that attempts to “quantify” whether a person exhibits good balance or attempts to “measure” balance improvement is also task specific. In other words putting too much emphasis on specific measurements (reductionism) without regard for understanding the entire process (biomechanical, physiological, neural, etc) may have little or no meaning.

Resulting in at best unproductive activity.

And at worst never allowing the player to find what works best for him/her.

For most (including the "experts"), attempts to “quantify” a good vs. bad swing starts to break down once the swing moves from beginner to intermediate in terms of proficiency. It’s “relatively” easy to see less than proficient (unproductive movements) swings in young players. Progressing (attempting the quantification of what is and what is not a good swing) to becoming virtually impossible to quantify what is an “optimum” swing at the Major League level.

Most of the swing commentary (analysis?) as to what constitutes a good vs. not so good swing that I see on web sites, books, video’s is geared for the 0-12 year old market place. And has questionable relevance to what Division 1, ML players do. Or should I say "need to do" to survive at that level. To figure out what the really good players are doing at this level, well that's a whole 'nother story???

And while the analytical is questionable, the instructional (the how to do it part) is far worse. Which lends support to those who view much of what is posted here and other places as hitting paralysis by analysis. Their belief being that hitting (the swing process) is really nothing more than see the ball, hit the ball. Or as Nike says “just do it”. Which at the highest levels of hitting may be true when comparing results obtained vs. instructional methods.

With respect to McGuire, just his physical size as compared to the “standard” player should raise a the question/issue in everyone’s mind that what is best for McGuire may not be best for the majority of other players.

And while Zig's doing his one camera, two dimensional analysis on a 180 x 120 resolution gif clip of McGuire shouldn’t he factor in McGuire’s bone mass to muscle mass ratio, moment of inertia ratio of thorax to thighs, shoe size vs. height (as in base of support for the center of gravity which is a function of the thorax to thigh ration of inertia’s), etc. (yes I am kidding…sort of).

This is not to say that there are certain swing “principles” that McGuire and most (all?) ML players exhibit. But “principles” are quite far removed from absolutes such as “the best” or the “optimum” swing based on attempts to quantify torque angles, hip to shoulder displacement times, etc. and then attempting to apply them "across the board”.

This is some of what skills vs. abilities are about. That skill is built from abilities. Much of ability being God given (genetics) such as body type (endomorph, ectomorph, mesomorph), tendon-bone attachment point locations (a fraction of an inch means significant increase in joint leverage), reaction time, etc. But certain abilities can be improved (response time can be improved but reaction time cannot). Which then changes the skill “picture”.

Some baseball professionals (as in those who are paid because of their “perceived” hitting knowledge) say that Ichiro has at least 5 different swings that he uses depending on what the task at hand is. Which again “begs” the question of what is and “optimum” swing???

All of which is may help explain why there are so many “experts”.

And is also the beauty (as in eye of the beholder) of what makes baseball, “baseball”.

"Kiitos, näkemiin ja onnea"