Movement Analysis
Neuromuscular Function: 4.1.1 Label a
diagram of a motor unit.
I. The Motor Unit:
II. The Structure of Muscle Tissue:
III. The Role of Neurotransmitters in stimulating
skeletal muscle contraction:
A. Acetylcholine (Ach):
B. Cholinesterase: enzyme that breaks down Ach
repolarizing the muscle fiber to await another
nerve impulse.
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.
Sliding filament cont.
*myosin heads can now
attach to active sites
on the actin filament.
*using ATP, the myosin
heads pulls on the
actin filament.
*myosin head releases
the actin when a new
ATP is formed.
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.
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.
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.
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)
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
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.
10. Pronation: rotating the palm down.
11. Supination: rotating
the palm up.
12. Rotation: turning the
body around a
longitudinal axis.
13. Inversion: when the ankle rolls outward.
14. Eversion: ankle
roles inward.
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.
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!
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.
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.
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)
b. Speed: describes the rate at which a body
moves from one location to another.
*obtained by dividing
the distance traveled
by the time taken.
*speed is described in
terms of magnitude
(amount) which
makes it a scalar
quantity.
c. Distance vs. Displacement
1. Distance: the length
of a path a body
follows.
2. Displacement: the
length of a straight
line joining the start
and finish points.
d. Velocity: the rate at which a body moves from
one location to another with both magnitude and
direction making it a vector quantity.
*obtained by dividing
the displacement by
the time taken.
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
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.
g. Impulse: the effect of force over time.
Calculated as the product of force and time.
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.
The Fosbury Flop!
*notice how the center
of gravity is located
outside the jumper’s
body.
Examples of the center of gravity outside the
body.
Levers: rigid structures hinged at one point
(fulcrum) to which forces are applied to two other
points (effort and load)
1. First Class Lever:
The fulcrum lies
between the effort
and load.
Ex. Triceps extension
and picking the chin
up from the chest.
2. Second Class Lever: the fulcrum lies at one end
with the effort at the other and the load in the
middle. Ex. Standing heel raise
3. Third Class Levers: the effort lies between the
load and the fulcrum. Ex. Biceps curl swinging a
bat.
Types of Levers
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.
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)
3. Third Law: For every action there is an equal
and opposite reaction. (every force involves the
interaction of two objects)