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: 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 Types of Joint Movement: Abduction: movement away from the body’s center. 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: Isotonic: describes concentric and eccentric muscle actions. Concentric: muscle is shortened during contraction. Eccentric: muscle is contracting while lengthening.
2. Isometric: muscle generates force without changing length. Ex 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) Agonist: muscle that causes the movement. 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. 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 Distance: the length of a path a body follows. 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 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 3. Third Law: For every action there is an equal and opposite reaction. (every force involves the interaction of two objects)