Anatomy Review n Major bones related to sport

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

Energetic Concepts Suzan Ayers, Ph. D Western Michigan University (thanks to Amy Gyrkos)

Terms (Burkett) n Mass: matter (has substance & occupies space) remains constant, qty of matter, ≠ weight n Weight: gravitational pull, varies with location, qty of matter + gravitational force Mass & weight are related but different n 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 more PRACTICAL 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 Law I. 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: Linear Straight 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

n Speed: how fast an object moves (dist/time) n Velocity: how fast & in what direction an object moves (Δ in position/time) n Acceleration: an object’s rate of speed change

Newton’s Second Law 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

Momentum (Abernethy et al. ) – Product of mass (matter) & velocity (directed speed) – Changes as a function of mass or velocity Δs n Velocity Δ: shot putter who spins faster one time vs another n Mass Δ: swinging a heavier bat – Short stopping time requires ↑ force to Δ momentum velocity n i. e. , ‘giving’ when catching a ball or landing n Key to injury prevention Conservation of momentum and energy: http: //www. youtube. com/watch? feature=fvwp&NR=1&v=0 MEVu_Elvwc http: //en. wikipedia. org/wiki/Newton's_cradle

Formula: F = ma Applied force F, Mass m, acceleration a Directly proportional (push 3 x harder=3 x> acceleration) Inversely proportional to mass (object that is 3 x 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 n “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 O 2) Acceleration of gravity n Uniform velocity of 32 ft/sec: due to constant ↑ in velocity, increasingly large distance is covered each sec. an athlete falls (Fig 2. 4, p. 19)

Center of gravity n Dead center (evenly distributed mass (p. 21 -3)) Gravity’s effect on flight n Vertical & horizontal forces applied: flight path cannot be changed once athlete is in flight n Ground reaction force: Earth’s push up on body (Fig 2. 10, p. 25)

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

Force: push/pull that changes shape or state of motion 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)

Projectiles (people/objects) Trajectory: flight path, sans gravity & air resistance, influenced by: Angle of release: influences shape of flight path 1) straight up=vertical flight path 2) closer to vertical (>45°)=height > distance 3) closer to horizontal (<45°)=distance > height 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

Terms (Abernethy et al. ch. 6 -7) Energetics: energy and its transformations n Centripetal: toward the center/axis n Centrifugal: away from the center/axis n n Moment of force: measure of the force needed to rotate a body around a point n Equilibrium: all points of body have = velocity – Static equilibrium: all points’ velocity/acceleration=0

n Kinetic energy: body’s mechanical energy due to its motion n Potential energy: mechanical energy by virtue of height above ground (gravitational in nature) n Power: rate of doing work (aka, strength x speed) – Positive: concentric contractions produce energy – Negative: eccentric contractions absorb energy n Elastic strain energy: stored energy in elastic tissues of muscles and tendons (elastic potential energy)

n Momentum & kinetic energy: an athlete on the move has both momentum and kinetic energy n Law of conservation of energy: one form of energy is exchanged for another; energy is conserved, not + or - n 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 Application 1) Which muscles most important in the vertical jump? (A, p. 89) n Quadriceps and gluteals SO WHAT? How & what muscles you train to improve VJ should dictate training programs when VJ matters to performance n

2) Relative to metabolic energy consumption… n 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 n

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. n n SO WHAT? ! Running less efficient than walking, ergo > caloric cost

Summary Terminology: definitions and applications Newton’s Laws: application to sport Next Week Linear & Angular Kinetics (ch. 4 -6 Burkett) Lab 1: Newton’s Laws