Movement Analysis
Jan 03, 2016
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)