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Thursday, July 14, 2011

Gaining Perspective On Specificity - Understanding what it means and how it applies pays huge dividends to your program - By Ken Mannie

Ken Mannie is the Head Strength/Conditioning Coach at Michigan State University, East Lansing, Mich. (mannie@ath.msu.edu)



Coaches of all sports are feverishly searching for every possible nugget of training information that will assist their athletes in becoming the very best they can be at the skills they need to perform. And in this search, we discover that there is no dearth of program designs that claim to be either sport or position specific. Some of these programs can weather the intense scrutiny they receive with such a proclamation, while others simply don’t have a leg to stand on.

The question all of us must ask whenever the sport- or position-specific claim is made is this: “Where is the preponderance of sound, reliable and valid scientific data to support this notion?” Is it just an opinion based solely on the success of a handful of athletes or is there enough peer-reviewed evidence to stamp it with unmitigated approval?

Specificity is, unquestionably, one of the most used — and misused — terms in the physical-training literature. In many instances, coaches are led to believe that any number of general activities performed on the field, court, and in the weight room, are specific to sport or position skills.

Dr. John Drowatsky, one of my early mentors and a highly respected, well-published expert in motor learning, once told me: “The litmus test for specificity is relatively simple; if skill ‘A’ is claimed to be specific to skill ‘B,’ then it follows that skill ‘B’ is specific to skill ‘A.’ If there is any doubt whatsoever about that conclusion, then you are probably dealing with similarity at best, not specificity.”

As coaches, we would like to believe that our training systems have been fine-tuned to the point where everything we are asking our athletes to perform has relevance to their sport and position. After all, that is one of the primary goals of implementing any type of training regimen.

Without delving too deeply into the complex neurological components of movement control, it is imperative to have a foundation of the basic architecture and functions as they relate to skill development and retention. This rudimentary knowledge assists you in making good decisions on what is important in skill mastery — as well as what might very well be a waste of time and effort.

In this installment, we will take a closer look at the Principle of Specificity, provide enough insight into the neuromuscular “wiring” to give you a backdrop and then discuss the points of proper application.

Note: This discussion addresses athletic skill specificity exclusively. Other indices of training specificity (i.e., power, speed, strength, hypertrophy, energy systems, etc.) have either been touched upon in past columns or will be addressed in future ones.

Open-Loop, Closed-Loop Control Systems
The planning, initiation, execution and subsequent completion of an athletic skill involve a highly complex aggregate of both central and peripheral nervous system structures. The central nervous system (CNS) is the command center for human movement; primarily the cerebral cortex, basal ganglia, cerebellum and the brain stem. These brain structures — along with their various nuclei and interdependent components — serve to receive, interpret, store, adjust, program and transmit vital movement information along their neural pathways (i.e., the spinal cord and its emanations) to the working muscles.

Once a skill is initiated, feedback from the proprioceptors and muscle spindles (receptors in joints and muscles that provide information on joint positions, muscle force production and overall body positioning while in motion) provide the CNS with information regarding the correctness of the movement. If time allows, incorrect movements can be altered to obtain a successful result.

All coordinated movements are controlled by either the open-loop or closed-loop neuromuscular systems. Both systems contain control centers that issue movement commands to the effectors (i.e., the muscles and joints involved in producing the desired movement). Each system also has a feedback pathway that travels from the effectors to the CNS.

The two systems, however, have very distinct, inherent differences. First, the closed-loop system relies on the concurrent feedback from the movement effectors (muscles) to the movement control center (CNS), thus closing the loop. As stated earlier, when a movement (e.g., athletic skill) is initiated, efferent information on the stored, correct execution of that movement is sent from the CNS to the appropriate muscles for action. Afferent information is subsequently returned to the spinal cord (i.e., feedback) to verify that the movement matches the encoded skill that is stored in the motor memory. If needed, and time willing, corrections can be made. All of this can occur in milliseconds — literally making it a race against time.

A simple, everyday analogy of a closed-loop control system is a thermostat regulator. There is a set room temperature (analogous to a previously learned and stored skill) that depends upon feedback from the thermostat sensors (analogous to the proprioceptors and muscle spindles) for the current room temperature, from which either the furnace or air conditioner is enabled to meet the set temperature (analogous to the correction of a skill, if needed, while it is in motion). Thus, a comfortable room temperature is maintained.

The open-loop system differs from the closed-loop system in that there is an initial command to the muscles and joints that contains all of the directives needed to execute the planned movement. Although feedback is both produced and available, it is not used to control the ultimate completion of the task. This is especially true in rapidly deployed movements that are executed and completed in minimal time. The received feedback, however, will be used to help plan a future bout of the skill, especially if there was an error in the first one.

An example of a mechanized, computer-regulated open-loop system is a traffic signal. There is a pre-set, sequential timing pattern for the red, yellow and green lights, that is impervious to any change in traffic flow, an accident, weather conditions, etc., unless a change is made manually.

Most athletic skills have a predominant system, though many complex, voluntary movements can exhibit characteristics of both closed-loop and open-loop processes.

As we take a closer look at the skill continuum, you will have a clearer understanding of which regulatory system oversees the skills of your sport.

Understanding The Skill Continuum
Athletic skills can be placed on a continuum of what are termed “closed” and “open” categories. (Note: It is important here that you do not confuse “closed” and “open” skills with the closed-loop and open-loop regulatory systems. We are now examining the actual categorizing of specific skills.)

Closed skills are at the low end of the continuum and take place under fixed, relatively stable and unchanging environmental conditions. They are predictable and have clearly defined beginning and ending points. Once the skill is initiated, feedback plays a minor role. In addition, the skills are usually self-paced in the sense that the performer begins movement when he or she is ready. Archery, golf, bowling, shooting a free throw in basketball, attempting a penalty kick in soccer, many track and field events and competitive weightlifting, represent a small sampling of closed skills.

Open skills, which are on the high end of the continuum, usually take place under the conditions of a temporarily or spatially changing environment. Simply put, the athlete must make decisions and adjustments while “on-the-run.”

A major distinction of open skills is the reliance on feedback in the decision-making process. It may be a visual cue (e.g., a quarterback adjusting to a blitz sighting, which forces him to look-up the “hot” receiver), an auditory cue (e.g., the offensive line reacting to the snap count), a pressure cue (e.g., a basketball player working around an offensive pick attempt) or some other external stimulus or sensory indicator.

All of the above are known as forced-paced skills, which are extremely complex due to the fact that the athletes must make quick decisions based upon the various feedback stimuli they are receiving and execute the appropriate adjustments within a very small window of opportunity.

Due to the variability, dependence on feedback and the mental pressure to make instant judgments under duress, it is evident that open skills require a higher level of learning than their closed-skill counterparts. It is vital that coaches understand the distinction between these two categories of skills when designing training programs.

Final Rep
Two tasks may appear — at first glance — to have many general underlying features in common but chances are they use completely unique neuromuscular encoding and feedback pathways. In essence, the fact that individuals are skilled (or, unskilled) in one activity does not indicate their skill level in a different activity. To be specific — at least in the case of a motor or athletic skill — requires that an athlete use exactness, not similarity, in preparation for all of the involved variables. This includes, but is not limited to, limb positioning, equipment, audio and visual cues, ever-changing feedback and even environmental conditions (e.g., crowd noise) whenever possible.

The more complex or open the skill is, the greater the importance of dissecting all of its key components and presenting them to your athletes in a sequential, learnable format. Then, as closely as possible, set up your practice situations (i.e., individual, group and team periods) in a manner conducive to the skill requirements they are expected to face on game day.

When the practice situations mirror the desired outcomes of the actual competition as closely as possible, inroads are being made toward true specificity.

Suggested Readings:
Magill, R., 2004, Motor Learning: Concepts and Applications, 7th ed., McGraw Hill Publishers, New York, New York.

Rosenbaum, D. 1991, Human Motor Control, Academic Press, Inc., San Diego, CA.

Schmidt, R., Wrisberg, C.A., 2000, Motor Learning and Performance: A Problem-Based Approach, Human Kinetics, Champaign, IL.




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