Movement Analysis

Central nervous system (CNS)

Central nervous system (CNS)

consists of the brain and spinal cord. 

Peripheral nervous system

is the arrangement of nerves extending from the spinal cord to other parts of the body. 

Motor neurons (motoneurons)

are nerves that carry info from the CNS to the muscles and signal for contraction. 

Cell body

contained in the spinal cord or in clusters just outside it called ganglia.

Dendrites

link the neuron to other neurons and information to flow.

Axon

main component to nerve signal transmission, similar to an electrical wire. Encased in myelin for insulation.

Neuromuscular junction

where the neuron meets the muscle.

Motor unit

a single motor neuron and the muscle it innervates.

Type I

slow twitch motor units consist of mainly slow twitch muscle fibers and have slower nerve transmission speeds and small muscle forces.

Type IIa

fast twitch oxidative (uses oxygen) motor units consist mainly of type IIa muscle fibers and have fast nerve transmissions.

Type IIb

fast twitch motor units with mostly fast twitch muscle fibers.

Striations

muscle fibers that appear striped due to the overlap of actin and myosin proteins within the muscle fiber.

Acetylcholine

is released and changes the electrical state of the muscle.

Cholinesterase

an enzyme that breaks down acetylcholine, is released and causes the muscle cell to repolarize and relax.

Calcium ions

are removed from the cell and returned to the sarcoplasmic reticulum via the calcium pump

Myofibril

A cylindrical organelle running the length of the muscle fibre, containing Actin and Myosin filaments.

Sarcomere

The functional unit of the Myofibril, divided into I, A and H bands.

Actin

A thin, contractile protein filament, containing 'active' or 'binding' sites. It slides past myosin casing contractions.

Myosin

A thick, contractile protein filament, with protrusions known as Myosin Heads. Pulls actin filaments towards one another by means of cross bridges.

Tropomyosin

An actin-binding protein which regulates muscle contraction.

Troponin

A complex of three proteins, attached to Tropomyosin.

Z Line

separates each sarcomere. It provides an anchor for proteins and also anchors the actin filaments to the ends of the sarcomere

M Line

is the centre of the A band and it is where adjacent myosin filaments anchor to each other

H Zone

is the centre of the sarcomere and has only myosin filaments

A Bands

are also known as dark bands and has both actin and myosin microfilaments - stays the same length during contraction

I Bands

are also known as light bands and have only actin microfilaments.

Sarcoplasmic reticulum

stores calcium ions and releases them into the sarcoplasm for the generation of action potential during muscle contraction.

Adenosine triphosphate (ATP)

is the sole fuel for muscle contraction.

Calcium

triggers contraction by reaction with regulatory proteins that in the absence of calcium prevent interaction of actin and myosin.

Slow-twitch

or type I, fibres have more mitochondria, store oxygen in myoglobin, rely on aerobic metabolism, have a greater capillary to volume ratio and are associated with endurance; these produce ATP more slowly.

Fast-twitch

or type II, fibers have fewer mitochondria, are capable of more powerful (but shorter) contractions, metabolize ATP more quickly, have a lower capillary to volume ratio, and are more likely to accumulate lactic acid.

axis

is a straight line around which an object rotates. 

Sagittal axis

passes horizontally from posterior to anterior and its formed by the intersection of the sagittal and transverse planes.

Frontal axis

passes horizontally from left to right and is formed by the intersection of the frontal and transverse planes.

Vertical axis

passes vertically from inferior to superior and is formed by the intersection of the frontal and sagittal planes.

Isometric Contraction

In general in this form of contraction the muscle length remains constant. It occurs when muscle force balances resistance and no joint movement occurs

Isotonic contraction

an increase in tension (load) results in changes in skeletal muscle length.

Concentric contraction

Concerns muscle actions that produce a force to overcome the load being acted upon.

Eccentric contraction

Refers to muscle action in which the muscle force yields to the imposed load.

Isokinetic contraction

When a muscle contracts so that the body segment to which it is attached moves at a constant speed around the joint, rarely found in sport.

Reciprocal Inhibition

When an agonist contracts to move a body segment, it is usual for the antagonist (the muscle with the opposite concentric contraction action) to relax.

Force

a push or pull on an object

Speed

maximum rate at which a person is able to move their body

Velocity

rate at which an object changes position

Displacement

distance measured in a stated direction

Acceleration

rate of change of velocity (speed/direction) per second

Momentum

the amount of motion possessed by a moving object

Impulse

force x time. The motion (momentum) of a body depends not only on the force, but also the duration (time) the force is applied.

Center of Mass

The point at which the body is balanced in all directions.

Load

The object that needs to be moved.

Fulcrum

Muscular force applied to move the load.

Effort

Joint around which the movement takes place.

Lever

Bones in the body serving as the structures for movement.

First Class levers

Fulcrum is between the effort and the load.

Second Class levers

Load is between components.

Third Class levers

Effort is between components.

Law of Inertia

An object will remain at rest or constant velocity unless acted upon by an external force.

Law of Acceleration

The rate of change of acceleration of an object is proportional to the force applied and acts in the direction of the force.

Law of Reaction

For every action there is an equal and opposite reaction.

Angular momentum

the product of the body's moment of inertia, and its angular velocity.

Moment of inertia

It determines the torque (force that causes rotation) needed for a desired angular acceleration about a rotational axis.

Angular velocity

is a ratio of the change of angular displacement and the time during which the change occurred. The rate of which a body spins/rotates/turns through an angle.

Projectiles

objects or athletes that are propelled in the air

Bernoulli Principle

is a principle in fluid dynamics that states that for an inviscid flow, an increase in the speed of the fluid occurs simultaneously with a decrease in pressure or a decrease in the fluid's potential energy.