6. III. The Role of Neurotransmitters in stimulating
skeletal muscle contraction:
A. Acetylcholine (Ach):
increases the post-
synaptic membrane’s
permeability to
sodium and
potassium ions
spreading the impulse
over the entire muscle
fiber.
7.
8. B. Cholinesterase: enzyme that breaks down Ach
repolarizing the muscle fiber to await another
nerve impulse.
12. A. The sliding filament theory:
Steps of a muscle
contraction:
*Ca++
are released by
the sarcoplasmic
reticulum.
*Ca++
binds to troponin
preventing the
blocking action of
tropomyosin.
13. Sliding filament cont.
*myosin heads can now
attach to active sites
on the actin filament.
*myosin heads pulls on
the actin filament,
decreasing the width
of the sarcomere Z-
lines get closer.
*myosin head releases
the actin when a new
ATP is formed.
14.
15.
16. Explain what is happening in an
eccentric, concentric, and
isometric contraction in relation
to the sliding filament theory?
17. V. Types of Muscle Fibers:
A. Slow Twitch: (type 1)
*smaller in diameter
*reddish color
*use aerobic resp. for
ATP supply
*contain more
mitochondria
*fire slowly, but take
long to fatigue.
18. B. Fast Twitch: used for short explosive
movements, stop and go sports.
Type IIA:
*large diameter
*white in color
*less mitochondria
*uses both anaerobic
and aerobic energy
transfer
Type IIB:
*same physical
characteristics as
Type IIA, but strictly
uses the glycolytic
anaerobic system.
19. Joint and Movement Type
A. Types of Joint
Movement:
1. Abduction:
movement away
from the body’s
center.
2. Adduction:
movement towards
the body’s center.
20. 3. Circumduction: making circular movements.
4. Dorsiflexion:
movement of the
ankle elevating the
sole. (digging in the
heel)
5. Plantar flexion:
extending the ankle
and elevating the
heel. (standing on
tiptoes)
21. 6. Elevation: occurs when a structure moves in a
superior (towards head) manner. Ex. Closing your
mouth/elevating the shoulders.
7. Depression:
movement is inferior
(towards feet). Ex.
opening your
mouth/lowering the
shoulders
22. 8. Extension: movement that increases the angle
between articulating elements opening the joint.
9. Flexion: decreases
the angle between
articulating elements
and closes the joint.
23. 10. Pronation: rotating the palm down.
11. Supination: rotating
the palm up.
12. Rotation: turning the
body around a
longitudinal axis.
24. 13. Inversion: when the ankle rolls outward.
14. Eversion: ankle
roles inward.
25. B. Types of Muscle Contraction:
1. Isotonic: describes
concentric and
eccentric muscle
actions.
a. Concentric: muscle
is shortened during
contraction.
b. Eccentric: muscle is
contracting while
lengthening.
26. 2. Isometric: muscle generates force without
changing length. Ex. Hand grip and plank position.
3. Isokinetic: the speed
of movement is fixed
and the resistance
varies with the force
exerted.
*requires special
equipment!
27. C. Reciprocal Inhibition: describes muscles on one
side of a joint relaxing while the other side is
contracting. (antagonistic pairs)
1. Agonist: muscle that
causes the
movement.
2. Antagonist: muscle
that works opposite
the agonist to return
the joint to its initial
position.
28. D. Delayed Onset Muscle Soreness: (DOMS)
The pain and stiffness
felt in muscles several
hours to days after
unaccustomed or
strenuous exercise.
*brought on by eccentric
contractions of the
muscle causing
pressure at the nerve
endings.
29. Biomechanics: the science concerned with the
internal and external forces acting on the human
body and the effects they produce on the body.
a. Force: a pushing or
pulling action that
causes a change of
state (rest/motion)
of a body.
*proportional to mass x
acceleration
*measured in Newtons
(N)
30. Types of Motion
• Translation: Motion along a path
– results in a change of location
examples: Position, Velocity, Net force
• Rotational: Rigid of a body about an axis
– Orientation of the axis, Angular position,
– Rotational motion occurs when an object
spins
• Deformation: motion inside of an object
like tension, buckling, bending, stretching,
twisting, compression, or expansion.,
32. Newton’s Laws of Motion in Sport
1. First Law: a body in
motion/rest will
remain in motion/rest
in a straight line
unless acted upon by
another force. Also
known as inertia.
33.
34. 2. Second Law: the rate of change of momentum
of a body is proportional to the force causing it and
the change takes place in the direction in which
the force acts. (F= M A)
35. Law of Acceleration
• The acceleration of an object is in the direction of the net
force. If you push or pull an object in a particular
direction, it accelerates in that direction.
• The acceleration has a magnitude directly proportional to
the magnitude of the net force. If you push twice as hard
(and no other forces are present), the acceleration is
twice as big.
• The magnitude of the acceleration is inversely
proportional to the mass of the object. That is, the larger
the mass, the smaller the acceleration for a given net
force (which is just as you’d expect from inertia).
36. 3. Third Law: For every action there is an equal
and opposite reaction. (every force involves the
interaction of two objects)
37. b. Speed: describes the rate at which a body
moves from one location to another.
*Distance/Time.
*speed is described in
terms of magnitude
(amount) which
makes it a scalar
quantity.
38. c. Distance vs. Displacement
1. Distance: (scalar) the
length of a path a body or
object follows
2. Displacement: (vector)
body or object changes
its position from on place
to another i.e. how far the
body or object has
moved horizontally,
vertically and laterally.
39. d. Velocity: the rate at which a body moves from
one location to another with both magnitude
(speed) and direction making it a vector quantity.
*Displacement/Time
40. e. Acceleration: is defined as the rate at which
velocity changes over time and the ability to
change ones speed from either a static position or
a moving state.
• Final velocity – initial
velocity/time
41. f. Momentum: is a vector describing a “quantity of
motion” and is the product of mass and velocity.
*an athlete can increase
their momentum by
either increasing their
mass or velocity.
42. g. Impulse: the effect of force over time.
Calculated as the product of force and time.
43. Speed and Acceleration Lab
• Moment of Inertia
– How difficult a body or object is to rotate
about an axis
• More mass further away from the axis
gives a great moment of inertia and
makes it more difficult to rotate
• Example
44. h. Center of mass: the point at which the body is
balanced in all directions.
*a change in body
position can change
the position of the
center of mass within
or outside the body.
*Different for individuals
*depends on age,
gender and position
of limbs during
athletics
45. a. Conservation of Momentum: momentum is
neither gained or lost within a closed system.
Total momentum before a collision equals the total
momentum after.
46. b. Angular Momentum: a measurement of an
objects tendency to continue to spin. It is the
product of angular velocity and moment of inertia.
1. Moment of inertia: the
distance from the
rotational axis.
2. Angular velocity: the
number of revolutions
per minute.
51. Center of Mass
• Center of mass and center of gravity are
effectively the same for the human body
• Point where the body is evenly distributed
• The "center of mass AN IMAGINARY
point on the body at which all the
individual forces acting on the body if
applied would produce the same effect IF
THAT IMAGINARY POINT WAS
CONNECTED RIGIDLY TO EVERY
OTHER POINT ON THE BODY“ Hula
hoop
54. Torque (moment)
• Force applied to an object that is free to
rotate around an axis, but the force does
not act through the axis
• Depends on:
– The size of the force
– The direction of the force
– How far it is applied from the axis of rotation
55. Torque
• In the golf swing, power comes from
good rotation, but how is this rotation
achieved?
• You need resistance, or a foundation
from which the rotation happens.
• This foundation is your hips. (rotate
back slightly).
• Relieving tension and reducing the
swing power (rotate too much)
56. Torque
• In sports usually torque is usually
created with implements
• But in humans the way muscles are
anatomically arranged relative to the
joints play a large part in determining
how much torque can be created
around each joint.
• Relates to levers (bones rotating
about axes such as the joints.
57. Linear Momentum and Linear
Impulse
• Linear momentum is a property an object
has due to its movement (p=mv)
• Linear impulse is force multiplied by the
time it acts for (J=Ft) (vector)
58. Impulse-momentum relationship
• Important when understanding changes of
motion
• Linear impulse is the change in linear
momentum (starting block 0-15)
• i.e. the size and direction of the change in
momentum of a body or object depend on
the force (muscles) applied to it and the
time for which that force acts.
59. Impulse-momentum relationship
• The task in many sport skills is to cause a
large change in the velocity of something.
In throwing events, the ball (or shot,
discus, javelin, or Frisbee) has no velocity
at the beginning of the throw, and the task
is to give it a fast velocity by the end of the
throw. We want to increase its momentum.
60. Impulse-momentum relationship
• Similarly, in striking events, the racket (or
bat, fist, club, or stick) has no velocity at
the beginning of the swing, and the task is
to give the implement a fast velocity just
before its impact. Our bodies may be the
objects whose momentum we want to
increase in jumping events and other
activities.
61. Impulse-momentum relationship
• Techniques used may be explained in part
by the impulse–momentum relationship.
• A large change in velocity is produced by
a large average net force acting over a
long time interval
• Limits on the forces humans are capable
of producing, many sport techniques
involve increasing the duration of force
application.
62. Throwing Exercise
• When was the largest impulse created?
• Why?
• Ball’s momentum changed, and the ball
left your hand with the fastest velocity.
• The large impulse was the result of a
relatively large average force being
exerted on the ball for a relatively long
time.
63. Throwing
• Smallest impulse?
• The ball’s momentum didn’t change very
much, and the ball left your hand with the
slowest velocity.
• The small impulse=relatively small
average force being exerted on the ball for
a relatively short time.
64. Angular Momentum
• Measures the amount of rotation a body or
object has
• Vector
• Angular effect of a force that does not act
through the axes of a freely rotating body
or object
65. • Newton's three laws of motion relate how
forces change motion they are applied into
daily activities and all sports.
66. Application
• How does our body move?
• Muscles play different roles in different
stages of movement depending on their
contraction type and requirements of the
action
67. Levers: a rigid rod, a fulcrum (axis), a resistance
force and an effort force. Resistance arm- distance
from resistance acts from fulcrum. Effort arm-
distance the effort acts from the fulcrum
1. First Class Lever:
The fulcrum lies between
the effort and load.
Rare in humans.
Ex. Triceps extension and
neck providing the effort
force to overcome
resistance force of
weight of head.
68. 2. Second Class Lever: effort force and resistance
force on the same side of the fulcrum. Effort arm
longer than resistance i.e. the effort froce is further
away from fulcrum Ex. Standing heel raise. Very rare
69. 3. Third Class Levers: effort and resistance forces
on the same side of fulcrum but effort arm is
smaller than the resistance arm i.e. the effort force
is closer to the fulcrum. Ex. Biceps curl swinging a
bat.
A small movement of the
lever near the fulcrum is
magnified by the length of
the leaver.
Lever moves through a
greater angle, and with
greater angular velocity.
Thus, advantage is in
range of motion and
speed.
71. Projectile Motion
1. Projectile: an object
that has been
dropped, thrown
vertically upwards or
thrown at an angle
following a parabolic
path and is subject to
the forces of gravity.
72. Projectile motion
• An object that is thrown into the air or
dropped and is acted upon by only the
forces of gravity, air resistance, and lift
• Analyses how objects move when thrown
into the air or dropped from a height
• Propelling force occurs only when the
object or body is in contact with the thing
that starts the motion. (hand, ground or
racket)
73. Projectile Motion
• As soon as the contact is lost the force no
longer exists and the object or body keeps
moving only due to newton's first law of
motion.
74. Factors Affecting Projectile Motion
a. Projection Speed:
most important factor
in determining how far
the object will go
because the range is
dependent on the
square of the project
speed.
75. b. Projection Angle: important for range but more
important accuracy.
Examples in
sports???
76.
77. c. Height of Release: the greater the height of
release the greater the distance.
78. The Bernoulli Principle:
States that as the
velocity of a fluid
increases, the
pressure exerted by
that fluid decreases.
Photo
Video
80. Drag
• As air moves past a sphere, two types of
drag are developed.
• The first is drag due to friction and second
separation of the airflow behind the golf
ball.
• As the air loses its ability to stick close to
the ball (known as the boundary layer), it
separates from the ball and creates lots of
little eddies (swirling of a fluid) that
basically try to pull the ball backwards.
81. Why does a dimpled ball help
delay airflow separation?
• Dimples create very small amounts of
turbulence near the ball's surface that
actually add energy to the air in the
boundary layer.
• More energy means more sticking power
which means the airflow separation occurs
later.
• Later the separation decreases the force
trying to pull the ball backwards and
allowing the ball to fly further.
