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) Within The Muscle Fiber –Myofibril 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 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 - 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