Transcript Neuromuscular Aspects Of Growth & Movement

Neuromuscular Aspects Of
Movement
Three Types Of Muscle In
Human Body
Smooth Muscle
 Cardiac Muscle
 Skeletal Muscle

– We will be concentrating mostly on the
neuromuscular aspects of skeletal muscle
Questions?
How Does Muscle Contraction Occur?
 How Does It Stop?

Anatomy of Skeletal Muscle
Attachment To Bone By Way Of Tendon
 Within The Belly Of The Skeletal Muscle

– Bundles of Fibers Arranged In Groups, Surrounded
by Fascia (Fasciculus)
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Within The Muscle Fiber
– Myofibril
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Within The Myofibril
– Sarcomere - The functional unit of the myofibril
2 Discoveries - Lending clues to these questions
(when viewed under electron microscope).
1. Calcium Ions were found to be present in
the muscle cell
 2. Small Protein Compounds Within The
Sarcomere Other Than Actin & Myosin
Were Found To Contribute To Contraction
Of The Muscle

– Tropomyosin
– Troponin
During Contraction
Ca++ Ions Were Very High - With
Relaxation, Ca++ Ion Concentrations Were
Low.
 Where did the Calcium come from and
where did it go after contraction?
 Calcium was found to be stored in the
CYTOPLASM (inside the muscle cell.

Crossbridge Theory

In order for contraction to occur, the "energized"
MYOSIN crossbridge must first attach to ACTIN.
The Sites Where Myosin Attach On The Actin
Filament Are Covered With Tropomyosin
– Basically, the sites are unavailable for crossbridging.


Troponin Is Bound To The Tropomyosin Molecule.
When Ca++ presents itself inside the sarcomere, it
binds with troponin to pull the tropomyosin molecule
away from the active sites on the ACTIN filament.
What occurs when the active sites
on ACTIN are exposed?

Myosin Attaches To These Active Sites And
A Crossbridge Occurs.
During Relaxation,

Tropomyosin reverts back to its original
position on the Actin molecule, and blocks
further attachment by Myosin.
What Triggers This Relaxation?
What Happens To the Ca++ Ions?
 They Are Stored In the Sarcoplasmic
Reticulum (A Storage Compartment)

What Caused the Ca++ Ions To Be Depleted
Within the Sarcomere (thus causing relaxation)?

Energy (ATP)
STRENGTH AND POWER
In Training Strength Becomes A Significant
Factor In Performance
 Speed Increases
 Max Strength Increases, ie: Max Lift On
Bench Due To Hypertrophy
 Performance Increases

QUESTION
What Are The Factors Which Contribute To
These Increases?
 How Could These Be Understood For
Future Development In Coaching?
 Are Their Differing Ways To Increase
Strength Depending On The Sport Or
Activity?

STRENGTH DEFINED
Max Ability To Apply Or Resist Force.
 One Who Curls 150 lbs. Has Twice The
Strength Of One Who Curls 75 lbs.
 How Measured?

POWER DEFINED
The Ability To Quickly Produce Force Over
A Distance
 Pw=Force x Distance / Time
 Example: Pushing A Sled In The Bobsled
Race:

– One person of equal strength pushes the sled
ten feet further than another, the first person
displayed more power.

How Measured?
OTHER ACTIVITIES REQUIRING A HIGH DEGREE
OF REPETITIVE MOVEMENTS OVER TIME
Muscular Endurance
 Defined As The Ability To Sustain
Contractions Over Time At Near Maximum
Force
 How Measured?

HOW DOES ONE COACH AND/OR DEVELOP POWER,
STRENGTH AND MUSCULAR ENDURANCE
Before Neuromuscular Adaptation Occurs,
What Must Be Accomplished?
 Answer: Stress To The Muscle (Overload
Principle)

– Just lifting or running at low intensity will not
build muscle strength and power. ie: yoga,
stretching, lifting without sufficient enough
stimulation.
WHAT RESEARCH SHOWS
Programs Where Stress In Loaded To
Muscle
 Increases Strength Very Quickly
 Increases Neuromuscular Changes Vary
Quickly
 How Quickly?
 In As Little As 3 to 6 Months.

CAN STRENGTH BE LOST AS
QUICKLY?
Yes, Once Levels of Strength Or
Adaptations Occur, It Can Be Quickly Lost.
 Atrophy.
 How Many Bouts Of Training Are Needed
To Maintain Strength & Power.

– Minimum: 1-2 Bouts / Week - Sufficient
SO WHAT ARE THE MECHANISMS
CONTRIBUTING TO STRENGTH GAINS
A Change In Motor Unit Recruitment
 Neurons To Muscle Produce Two Types Of
Responses.
 a. Inhibitory Impulses
 b. Excitatory Impulses

INHIBITORY IMPULSES
Natures Way Of Protecting Muscle From
Over Exertion.
 Called Autogenic Inhibition Reflex (AIR)

Training Possibly Decreases The
Inhibitory Impulses.

So Gains In Strength May Well Be Due to
Decreased AIR.
OTHER REASONS FOR STRENGTH
GAINS
Hypertrophy Of The Muscle.
 What Causes Hypertrophy?

– a. Increased Testosterone Hormone

Females Have However Shown Increased
Strength Without Hypertrophy.
Hypertrophy Alone Does Not
Account For Increased Strength.
DIFFERENCE BETWEEN ACUTE AND
CHRONIC HYPERTROPHY
 Acute or Transient Hypertrophy - Caused
By Intermuscular Fluid
 Chronic or Long Term - Caused By
Structural Changes

CONFLICTING EVIDENCE
Hyperplasia - A Splitting Of Muscle Fiber 10% In The Research.
 Increased Sarcoplasm
 Increased Connective Tissue and Size
 Enlargement In Size Of Fiber - Myofibrils

MORE RECENT SPECULATIONS ON
STRENGTH
Caused By A Change In Structural Nature
Of:
 Type IIb (Fast Twitch) Fiber Type
 Type IIa - Fatigues Less
 Type IIb - Fatigues Very Quickly

PROCESS OF STRUCTURAL
CHANGE
Through Later Repetitions Cramping
Occurs In Type II Fibers.
 Additional Reps Tears The Fibers From The
Connective Tissues At Their Weakest Links
 Damage = Remodeling In Three Phases
 Inflammation Phase
 Clean-Up Phase
 Adaptive Growth

MOST WIDELY ACCEPTED THEORY
FOR INCREASED MASS
INCREASE IN MYOFIBRIL AND
FILAMENTS
 Providing More Crossbridges and More
Contractile Force.

Question: With Weight Training, Is There A Change
In The # of Myofibrils Or # Of Muscle Fiber?

Small Increases In % of Muscle Fibers Are
Present, But Not Significantly
CAN MUSCLE FIBER TYPES
CHANGE?
Possibly Across Type II Fibers, But Not
From Type II to Type I Fibers.
 Neither Strength Of Endurance Training
Seems To Change Type I to II Or In Vise
Versa.

HOW DOES ONE INCREASE
POWER?

Since Power Is A Product Of Speed and
Strength, It Is Obvious That Strength
Increases Encourages Increases In Power.
HOW DO WE INCREASE
MUSCULAR ENDURANCE?
Increase Repetitions
 Decrease Resistance
 Muscle Endurance Has Been Shown To
Improve With Strength Gains.
 Direct Correlation Between Absolute
Muscular Endurance and Strength

WHY DO WE SEE INCREASED MUSCLE
ENDURANCE AS A RESULT OF STRENGTH GAINS?
Increased Vascularization Within The
Muscle Yielding
 Better Circulation
 Increased Removal of Waste
 Increased Availability of Fuels For Energy
ie: Glucose
 Increased Availability Of Oxygen

TYPES OF CONTRACTIONS
Static
 Example: Isometrics
 (Iso = Same) (Metric = Change In Length)

STATIC CHARACTERISTICS
Energy Is Still Being Utilized - Due To
Contractions
 Fatigue Can Still Be Met
 LA & H++ ion Build Up Is Still Present
 Neural Activity Continues During
Contraction

MEASUREMENT OF STATIC
STRENGTH
Hand Grip Dynamometer - Measured in
Kilograms
 How Can We Explain Isometrics In Terms
Of Work?
 Work = Force x Distance / Time
 Research - Mueller (1950) showed that 6-7
bouts/week significantly improves strength

DYNAMIC STRENGTH
Strength Exercises Using Movement
 Example:

– Isotonic
– Isokinetic
ISOTONIC
Weight or Resistance Is The Same During
The Entire Range Of Movement
 Points:
 Contraction Occurs During Lifting
 Mechanical Advantages Play A Role
Throughout Range Finding One's Max Can
Be A Complex Matter

ISOKINETIC

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
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Speed Is Utilized Throughout The Entire Range Of
Motion
Points:
Speed Is Consistent
Degrees Of Motion Can Be Regulated.
The Slower The Velocity That Movement Is Occurring
Through A Range, the More Recruitment Of Muscle
Fiber
Greater The Force, The Greater The Resistance
Theoretically, This Method Should Lead To Greater
Strength Improvement.
MEASUREMENT OF ISOTONIC &
ISOKINETIC
Isotonic - Free Weights, Max Lift
 Isokinetic - Hydraulic Lifts, Leaper
Machine.

POWER
How Does Power Differ From Strength?
 Power = Work (F x D) / Time
 There Is A Time Frame
 Tests On Power Were Developed To See If
Subjects Could Move With Resistance Over
A Time Period.

TYPES OF POWER TESTS
S.J. Sargent Jump Tests - Curvilinear
Relationship Between Vertical Jump &
Force. Learning Does Take Place.
 M.K. Force & Power Test - Has The Aspect
Of Learning Also, Relates To Skill.
 Wingate Power Test - Intermittent Power
Test - Revolutions/Time @ 7% Body
Weight Resistance

– Most Reliable
MUSCLE ENDURANCE
Defined: The Ability To Sustain At High
Levels Of Contraction Over Time
 Associates Well With Muscle Metabolism
 Test Of Endurance Using Less Resistance
But Maximum Repetitions
 Assessment

– Push Up Test Over Time
– Sit Up Test Over Time
COMPARATIVE DIFFERENCES IN FORMS
OF WEIGHT TRAINING
TOPI C
ISOKINETIC ISOMETRIC ISOTONIC
Rate Of Str Gain
E
Rate of End. Gain E
Time/Training
E
Expense
G
Less Mus. Soreness E
Less I njury
E
Skill Improv ement E
Measurement
P
P
P
P
E
G
P
P
G
G
G
G
P
P
G
E
E