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Response Component - Neurophysiological
Perspective
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Muscles are composed of muscle
fibers.
Muscle fibers within a muscle
group are innervated by several
motor neurons.
Any given muscle fiber is
innervated by one motor neuron.
A motor neuron and the muscle
fibers it innervates form what is
called a motor unit.
The motor unit is the most basic
element of motor control.
Response Component - Neurophysiological
Perspective
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The number of muscle fibers in a motor unit varies from effector
to effector:
– hand and eye fewer than 100 muscle fibers occupy a motor unit
– lower leg a single motor unit may contain as many as 1000 muscle
fibers.
– generally, the larger the number of muscle fibers in a motor unit,
the less precise the movements it allows.
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It is impossible to activate voluntarily some but not all of the
muscle fibers within a motor unit.
It is possible to recruit some motor units but not others within a
muscle.
Response Component - Neurophysiological
Perspective
Bartlett (1942) said it best when he wrote:
We may, perhaps, see the beginning of skill
where nervous mechanisms acquire the character
of 'graded' response adjusting the amount of
their action to the variable intensity of the
stimulus.
The Graded Response
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Performing motor activities at high levels requires the
capacity to adjust activation level during the execution
of a response.
What are some examples of sport skills in which
gradation of response is required in the midst of other
movements that are executed at near maximum force?
NEURONS FROM
FI BERS
HI
GHER ENTER
CENTERS
A
CONTRACTI ON
AND AT W HAT
RATE W I LL THEY
FI RE?
SP I NAL CORD
D
FROM P ERI P HERY
FROM P ERI P HERY
M OTOR UNI T
A
B
C
W HEN W I LL THESE M USCLE
f i ber s ent er t he cont r act i on
and at w hat r at e w i l l t hey
f i r e?
Response Component
The Graded Response - Sequence
Throwing
Sequential
Biceps
Triceps
Co-contraction
Biceps
Triceps
Summary
Motor Control
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Complex responses have complex mediating processes: Perceptual,
Decision Making, Response Organization.
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Limited information processing capabilities requires us to develop
strategies for reducing information load or increasing capacity:
organization of stimuli, rehearsal of situations requiring decisions,
“chunking” and autonomous execution of response components,
massive amounts of practice.
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Psychological states and manipulations can enhance or inhibit
processing at each stage.
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Understanding and empathy should dictate the nature of our
interactions with athletes.
An Information Processing Model Applied to
Teaching: Gentile (1972)
Stage 1: getting the Idea:
Goal regulatory
Perceptual
Processes
Selective Motor Plan
Attention Formulation
Response
Execution
Decision &
Response
Organization and
Execution
Decision
Feedback
Processes
KP & KR
Next
Response
Stage Two: Fixation/Diversification:
G
Was the movement executed as planned?
O
Yes
A
L
Yes
A
C
H
No
Got the idea
Something’s
Wrong
No
Surprise
Everything’s Wrong
Stage Two begins after a few Yes/Yes outcomes
Closed vs. Open Skills:
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Closed skills: the environment remains constant; need to
decrease variability in producing a motor pattern similar to
the one learned during Stage 1. (less dependent on
monitoring the external environment).
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Open skills: the environment is variable; need to diversify
the original motor pattern.; regulatory stimuli change, and
variation of the motor pattern must occur. The learner
must develop a larger repertoire of responses. (slight or
large modifications of spatial/temporal components within
a common generic formula).
Teaching Guidelines (Stage 1):
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The goal.
– Teacher needs to provide goal clarity. If a teacher
rushes to the movement, it is possible that the
learner thinks that the movement is the goal rather
than the outcome to be produced.
– Teacher should create a specific environmental
problem, and establish an adequate motivational
level.
Regulatory stimulus subset (Stage 1)
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Teacher can identify regulatory stimulus subset;
– Should practice be like a game or some subset of the
game?
– How much non-regulatory stimuli should be available
during learning (open vs. closed skills).
– Progression from simple to complex?
Selective Attention (Stage 1)
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Teacher can help student to attend to regulatory stimuli.
– Verbally, "guided discovery" or verbal problem solving.
Instruction pertaining to orienting movements may be
required. Use of peripheral vision, where to be to look!
– For open skills, instruction by teacher of what will
happen helps learner to know what to look for when it
occurs.
Formulation of the Motor Plan (Stage 1):
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Only when the movement form is the goal (diving and
gymnastics) must the teacher actively restrict the learner's
responses.
– Otherwise any movement that effectively and
consistently matches the environmental conditions
should be permitted.
Response Execution(Stage 1):
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Teacher should reduce distracting elements including
his/her own verbal comments.
– May facilitate the decision process that will follow by
providing certain instructional sets regarding the kinds
of information that will soon arrive.
Feedback and Decision Making (Stage 1):
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Feedback: The need for additional information beyond
what is normally available is not clear.
– The teacher should delay comments for a short
period after a response so that the learner can
process and encode the information resulting from
movement.
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Decision: May help in decision process. Teacher will be
very involved when "everything’s wrong" occurs, and to
varying degrees until Yes/Yes.
Stage II. Fixation/Diversification
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Closed skills: hold regulatory stimuli constant and
add non-regulatory stimuli.
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Open skills: vary regulatory stimuli systematically
enabling performer to acquire the repertoire of motor
patterns that match the total number of stimulus
subsets.
– How to do this has not been investigated. Increased
variability would seem to be essential. Either by letting
things fluctuate randomly or doing it on a probability
basis.
Feedback and Decision Processes:
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Closed Skills: KP is essential.
– Perhaps, augmented feedback would be most usable if
administered just prior to the next response during
when the student is formulating their motor plan (but
who knows for sure?).
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Open Skills:In the diversification phase, try to develop as
many motor patterns as is required.
– Here S may need help with feedback on the regulatory
conditions that existed and the response that was
executed. Unclear whether KP is valuable here since
he will move differently on the next trial.