Musculoskeletal ReviewMusculoskeletal Review 2 types of functions of bone2 types of functions of bone

mechanical, physiologicalmechanical, physiological 1° difference in bone structures1° difference in bone structures

organizationorganization Movement planesMovement planes

Transverse, Sagittal, FrontalTransverse, Sagittal, Frontal Muscle-tendon unitMuscle-tendon unit

bone-tendon-muscle-tendon-bonebone-tendon-muscle-tendon-bone Motor unitMotor unit

Motor neuron and all muscle fibers it Motor neuron and all muscle fibers it innervatesinnervates

5 main properties of muscle5 main properties of muscle– ExcitabilityExcitability– ContractilityContractility– Conductivity Conductivity – ExtensibilityExtensibility– ElasticityElasticity

Types of muscular contractionsTypes of muscular contractions– Concentric (shortening)Concentric (shortening)– Eccentric (lengthening)Eccentric (lengthening)– Isometric (same length)Isometric (same length)– Isokinetic (same speed)Isokinetic (same speed)– Isotonic (same tension)Isotonic (same tension)

SynergisticSynergistic– Contributing to desired motion, often by Contributing to desired motion, often by

stabilizationstabilization AntagonisticAntagonistic

– Opposing desired motionOpposing desired motion Components of muscular fitnessComponents of muscular fitness

– StrengthStrength -Balance-Balance– PowerPower -Flexibility-Flexibility– Muscular enduranceMuscular endurance -Agility-Agility– Power endurancePower endurance– Reaction timeReaction time– QuicknessQuickness– SpeedSpeed

Energetic ConceptsEnergetic Concepts

Dr. Suzan AyersDr. Suzan Ayers

Western Michigan UniversityWestern Michigan University(thanks to Amy Gyrkos)

Terms Terms (Carr)(Carr) MassMass: matter, remains constant: matter, remains constant

WeightWeight: gravitational pull, varies with : gravitational pull, varies with locationlocation– You weigh < @ equator, > toward polesYou weigh < @ equator, > toward poles

2 characteristics of inertia 2 characteristics of inertia (resistance to change)(resistance to change) ::

-to resist motion-to resist motion-to persist in motion (in a straight line)-to persist in motion (in a straight line)

In linear movement, mass=inertia In linear movement, mass=inertia (> mass=> (> mass=> inertia)inertia)

Rotary inertia involves how mass is distributed Rotary inertia involves how mass is distributed relative to axis of rotationrelative to axis of rotation

Factors influencing inertia: friction, air resistanceFactors influencing inertia: friction, air resistance(e.g., base runner sliding, ski jumping)(e.g., base runner sliding, ski jumping)

More massive athletes resist change moreMore massive athletes resist change morePRACTICAL EXAMPLES OF SMALL/STRONG ATHLETESPRACTICAL EXAMPLES OF SMALL/STRONG ATHLETES

Newton’s First LawNewton’s First LawI. Law of InertiaI. Law of Inertia

– Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it

SpeedSpeed: how fast an object moves: how fast an object moves

AccelerationAcceleration: an object’s rate of speed : an object’s rate of speed changechange

VelocityVelocity: how fast & in what direction an : how fast & in what direction an object movesobject moves

Momentum Momentum (Abernathy et al.)– Product of mass (matter) & velocity (directed

speed)

– Changes as a function of mass or velocity mass or velocity ΔΔss Velocity Velocity ΔΔ: shot putter who spins faster one time : shot putter who spins faster one time

vs anothervs another Mass Mass ΔΔ: swinging a heavier bat: swinging a heavier bat

– Short stopping time requires ↑ force to ΔΔ momentum velocitymomentum velocity i.e., ‘giving’ when catching a ball or landing Key to injury prevention

Conservation of momentum and energy:http://www.walter-fendt.de/ph11e/ncradle.htm

Gravity’s effect on athletic performanceGravity’s effect on athletic performance ““Thin” air @ altitudeThin” air @ altitude: same proportion of : same proportion of

gases, but as altitude gases, but as altitude ↑↑, standard volume , standard volume of air has < of each gas of air has < of each gas (have to work (have to work harder to get same Oharder to get same O22))

Acceleration of gravityAcceleration of gravity Uniform velocity of 32ft/secUniform velocity of 32ft/sec: due to : due to

constant constant ↑ ↑ in velocity, increasingly large in velocity, increasingly large distance is covered each sec. an athlete distance is covered each sec. an athlete falls falls (Fig 2.1, p. 17)(Fig 2.1, p. 17)

II. Law of AccelerationII. Law of Acceleration– Change of motion is proportionate to the

force impressed and is made in the direction of the straight line in which that force is impressed

Objects accelerate in the direction pushedObjects accelerate in the direction pushed

Newton’s Second LawNewton’s Second Law

Formula:Formula: F = ma F = ma Applied force FF, Mass mm, acceleration aa

Directly proportional (push 3x harder=3x> acceleration)

Inversely proportional to mass (object that is 3x heavier moves 1/3 slower; bowling ball vs. volleyball)

If force or time ↑, so does velocity (i.e., keeping contact w/ ball longer = > time)

M = mv M = mv Momentum=mass x velocity *no

movement=no M

Center of gravityCenter of gravity Dead center Dead center (evenly distributed mass (evenly distributed mass (p. (p.

21)21)))

Gravity’s effect on flightGravity’s effect on flight Vertical & horizontal forces appliedVertical & horizontal forces applied: flight : flight

path cannot be changed once athlete is in path cannot be changed once athlete is in flightflight

Ground reaction forceGround reaction force: Earth’s push up on : Earth’s push up on body body (Fig 2.7, p. 23)(Fig 2.7, p. 23)

III. Law of Action-ReactionIII. Law of Action-Reaction– Every action has an = and opposite reaction

Newton’s Third LawNewton’s Third Law

ForceForce: push/pull that changes shape or : push/pull that changes shape or state ofstate of

motion of athlete or objectmotion of athlete or object

VectorVector: a quantity (of force) with direction: a quantity (of force) with direction

Force vectorForce vector: when direction & amount of : when direction & amount of applied force are knownapplied force are known

Relevance? Relevance? Vector analysis is learned by Vector analysis is learned by athletes practicing various combinations athletes practicing various combinations of horizontal and vertical pathways of horizontal and vertical pathways (lead (lead passing routes, etc.)passing routes, etc.)

Linear motionLinear motion: straight line movement : straight line movement (100m dash)(100m dash)

Angular motionAngular motion: body moves through an : body moves through an angle or number of degrees around an angle or number of degrees around an axis axis (360(360°° dunk) dunk)

General motionGeneral motion: combination of : combination of linear/angularlinear/angular

TrajectoryTrajectory: flight path, influenced by gravity and : flight path, influenced by gravity and air resistance; influenced by 3 factors:air resistance; influenced by 3 factors:

Angle of releaseAngle of release: influences shape of flight path; : influences shape of flight path; 1) straight up=vertical flight path1) straight up=vertical flight path

2) closer to vertical 2) closer to vertical (>45(>45°)°)=height > distance=height > distance

3) closer to horizontal 3) closer to horizontal (<45(<45°)°)=distance > height=distance > height

Speed of releaseSpeed of release: apex of flight path : apex of flight path ↑ ↑ as speed as speed ↑↑

Height of releaseHeight of release: relative to landing surface; : relative to landing surface; velocity velocity (speed and direction)(speed and direction), height and angle of , height and angle of takeoff/release combine to determine flight takeoff/release combine to determine flight pathpath

ProjectilesProjectiles (people/objects)(people/objects)

EnergeticsEnergetics: energy and its transformations: energy and its transformations CentripetalCentripetal: toward the center/axis: toward the center/axis CentrifugalCentrifugal: away from the center/axis: away from the center/axis

Moment of forceMoment of force: measure of the force : measure of the force needed to rotate a body around a pointneeded to rotate a body around a point

EquilibriumEquilibrium: all points of body have = : all points of body have = velocityvelocity– Static equilibriumStatic equilibrium: all points’ : all points’

velocity/acceleration=0velocity/acceleration=0

TermsTerms (Abernathy et al. ch.6)(Abernathy et al. ch.6)

Kinetic energyKinetic energy: body’s mechanical energy : body’s mechanical energy due to its motiondue to its motion

Potential energyPotential energy: mechanical energy by : mechanical energy by virtue of height above ground virtue of height above ground (gravitational in (gravitational in nature)nature)

Elastic strain energyElastic strain energy: stored energy in : stored energy in elastic tissues of muscles and tendons elastic tissues of muscles and tendons (elastic (elastic potential energy)potential energy)

PowerPower: rate of doing work : rate of doing work (aka, strength x speed)(aka, strength x speed)

– PositivePositive: concentric contractions produce energy: concentric contractions produce energy– NegativeNegative: eccentric contractions absorb energy: eccentric contractions absorb energy

Momentum & kinetic energyMomentum & kinetic energy: an athlete on : an athlete on the move has both momentum and kinetic the move has both momentum and kinetic energyenergy

Law of conservation of energyLaw of conservation of energy: one form of : one form of energy is exchanged for another; energy is energy is exchanged for another; energy is conserved, not gained/lostconserved, not gained/lost

FrictionFriction: when an object moves while in : when an object moves while in contact w/ another objectcontact w/ another object– StaticStatic: contacting surfaces of resting objects : contacting surfaces of resting objects > resistance than > resistance than

slidingsliding– SlidingSliding: between two sliding objects : between two sliding objects > resistance than rolling> resistance than rolling– RollingRolling: between a rolling object and a supporting/contacting : between a rolling object and a supporting/contacting

surfacesurface

*It is easier to keep an object moving than to start it moving*It is easier to keep an object moving than to start it moving

Points of ApplicationPoints of Application1) Which muscles most important in the 1) Which muscles most important in the

vertical jump? (A, p. 89)vertical jump? (A, p. 89)

Quadriceps and glutealsQuadriceps and gluteals

SO WHAT?SO WHAT?

How & what muscles you train to improve How & what muscles you train to improve VJ should dictate training programs when VJ should dictate training programs when VJ matters to performanceVJ matters to performance

2) Relative to metabolic energy 2) Relative to metabolic energy consumption…consumption…

The cost associated with quiet standing is The cost associated with quiet standing is ~30% higher than resting (sitting/lying ~30% higher than resting (sitting/lying down)down)

SO WHAT?SO WHAT?

After contests, have your athletes cool After contests, have your athletes cool ↓↓ slowly vs drop to the ground suddenlyslowly vs drop to the ground suddenly

3) Walking saves met energy by converting 3) Walking saves met energy by converting gravitational potential energy into gravitational potential energy into forward kinetic energy. Running forward kinetic energy. Running stores/re-uses elastic strain energy, but stores/re-uses elastic strain energy, but less efficiently than pendulum-like less efficiently than pendulum-like walking mechanism.walking mechanism.

SO WHAT?!SO WHAT?!

Running less efficient than walking, ergo Running less efficient than walking, ergo > caloric cost> caloric cost