Anatomy Review

Major bones (related to sport)

Major muscle groups

http://www.bbc.co.uk/science/humanbody/body/factfiles/muscle_anatomy.shtml

Energetic Concepts

Suzan Ayers, PhDWestern Michigan University

(thanks to Amy Gyrkos)

Terms (Burkett) Mass: matter (has substance & occupies

space) remains constant, qty of matter, ≠ weight

Weight: gravitational pull, varies with location, qty of matter + gravitational force

Mass & weight are related but different

Inertia: resistance to change

2 characteristics of inertia:-resist motion-persistence in motion (in a straight line)

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

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

Rotary inertia involves how mass is distributed relative to axis of rotation (see ch.4)

Factors influencing inertia: friction, air

resistance(e.g., base runner sliding, ski jumping)

Newton’s First LawI. 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

Object Movement Classifications:LinearStraight line motion rare in sports

Angular (circular or rotary)Rotary movement around an axis (i.e., arms: shoulder,

elbow, wrist)

General motion (combo platter of linear/angular)

See p. 15 for examples in sport-Gymnast on balance beam-Ski jumper-Wheelchair racer

Speed: how fast an object moves (dist/time)

Velocity: how fast & in what direction an object moves (Δ in position/time)

Acceleration: an object’s rate of speed change

II. 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 pushed

Newton’s Second Law

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

speed) – Changes as a function of mass or velocity Δs

Velocity Δ: shot putter who spins faster one time vs another

Mass Δ: swinging a heavier bat– Short stopping time requires ↑ force to Δ

momentum velocity i.e., ‘giving’ when catching a ball or landing Key to injury preventionConservation of momentum and energy:http://en.wikipedia.org/wiki/Newton's_cradle

http://www.youtube.com/watch?feature=fvwp&NR=1&v=0MEVu_Elvwc

Formula: F = ma Applied force F, Mass m, acceleration a

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 Momentum=mass x velocity *no

movement=no M

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

gases, but as altitude ↑, standard volume of air has < of each gas (have to work harder to get same O2)

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

constant ↑ in velocity, increasingly large distance is covered each sec. an athlete falls (Fig 2.4, p. 19)

Center of gravity Dead center (evenly distributed mass (p. 21-

3))

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

path cannot be changed once athlete is in flight

Ground reaction force: Earth’s push up on body (Fig 2.10, p. 25)

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

Newton’s Third Law

Force: push/pull that changes shape or state ofmotion of athlete or object

Vector: a quantity (of force) with direction

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

Relevance? Vector analysis informs athletes’ practice of various combinations of horizontal and vertical pathways (i.e., lead passing routes-see p.29)

Trajectory: flight path, sans gravity & air resistance, influenced by:

Angle of release: influences shape of flight path1) straight up=vertical flight path2) closer to vertical (>45°)=height > distance3) closer to horizontal (<45°)= height < distance

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

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

Projectiles (people/objects)

Energetics: energy and its transformations Centripetal: toward the center/axis Centrifugal: away from the center/axis

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

Equilibrium: all points of body have = velocity– Static equilibrium: all points’

velocity/acceleration=0

Terms (Abernethy et al. ch.6-7)

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

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

Power: rate of doing work (aka, strength x speed)– Positive: concentric contractions produce energy– Negative: eccentric contractions absorb energy

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

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

Law of conservation of energy: one form of energy is exchanged for another; energy is conserved, not + or -

Friction: when an object moves while in contact with another object– Static: contacting surfaces of resting objects > resistance

than sliding– Sliding: between two sliding objects > resistance than rolling– Rolling: between a rolling object and a supporting/contacting

surface*It is easier to keep an object moving than to get it moving

Points of Application1) Which muscles most important in the

vertical jump? (A, p. 89)

Quadriceps and gluteals

SO WHAT?How & what muscles you train to improve

VJ should dictate training programs when VJ matters to performance

2) Relative to metabolic energy consumption…

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

SO WHAT?After contests, have your athletes cool ↓

slowly vs drop to the ground suddenly

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

SO WHAT?!

Running less efficient than walking, ergo > caloric cost

Terminology: definitions and applications

Newton’s Laws: application to sport

Summary

Next WeekLinear & Angular Kinetics (ch. 4-6 Burkett)

Lab1: Newton’s Laws