Anatomy Review
Major bones (related to sport)
Major muscle groups
http://www.bbc.co.uk/science/humanbody/body/factfiles/muscle_anatomy.shtml
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)
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
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