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)