Chapter 2 - Neuromuscular Fundamentals

Epimysium, perimysium, and endomysium

3 layers of connective tissue surrounding muscle fibers which transmit force to tendon

Isokinetics

A type of dynamic exercise usually using concentric and/or eccentric muscle contractions in which the speed of movement is constant and muscular contraction occurs throughout the movement

Reciprocal Inhibition

Activation of the motor units of the agonist causes an inhibition of the motor units of the antagonist

Muscle force-velocity relationship

As the amount of force needed increases with greater loads, the velocity of concentric contraction decreases proportionally

Muscle length-tension relationship

As the length increases the amount of active tension that can be developed increases.

Type IIa - Fast fibers

Can produce greater forces due to a greater shortening velocity but fatigue quickly

True synergist

Contract to prevent an undesired joint action of the agonist and have no direct effect on the agonist action

Eccentric contraction

Contraction in which muscle is being lengthened

Concentric contractions

Contractions that involve the muscle developing active tension as it shortens

Neutralizers

Counteracts or neutralizers the action of other muscles to prevent undesirable movements

One motor neuron and all the muscle fibers it innervates

Define motor unit

Active Tension

Dependent on the number of motor units and their respective muscle fibers recruited in a given contraction

Passive Tension

Developed as a muscle is stretched beyond its normal resting length

Biceps brachii - contracting muscle (eccentric) Triceps brachii - relaxed

During extension of a bicep curl what is happening to the biceps brachii and triceps brachii?

Biceps brachii - relaxed Triceps brachii - contracting muscle (eccentric)

During flexion of an elbow extension what is happening to the biceps brachii and triceps brachii?

Eccentric contraction

During landing from a jump the quadriceps would be under what type of contraction?

Biceps brachii - relaxed Triceps brachii - contracting muscle (concentric)

During the extension of an elbow extension what is happening to the biceps brachii and the triceps brachii?

Biceps brachii - contracting muscle (concentric) Triceps brachii - relaxed

During the flexion of a bicep curl what is happening to the biceps brachii and triceps brachii?

Force > Resistance

Force-Resistance relationship for a concentric contraction?

Force < Resistance

Force-Resistance relationship for an eccentric contraction?

Force = Resistance

Force-Resistance relationship for an isometric contraction?

Sarcomere

Functional unit of muscle where force is developed

Type I - Slow fibers

Have a higher resistance to fatigue, but generally produce less tension

Helping synergist

Help another muscle move the joint in the desired manner and simultaneously prevent undesired actions

1

How many planes of motion does the talocrural joint have

Shortening

If there is a concentric contraction what is the change in agonist muscle length?

Lengthening

If there is a concentric contraction what is the change in antagonist muscle length?

Lengthening

If there is an eccentric contraction what is the change in agonist muscle length?

Shortening

If there is an eccentric contraction what is the change in antagonist muscle length?

No change

If there is an isometric contraction what is the change in agonist muscle length?

No change

If there is an isometric contraction what is the change in antagonist muscle length?

Agonist muscles

Known as primary movers or as muscles most involved

Golgi tendon organs

Located in the tendon close to the muscle-tendon junction, are continuously sensitive to both muscle tension and active tension. Respond by relaxing the muscle.

Antagonist

Located on the opposite side of the joint from the agonist and work in cooperation with agonist muscles by relaxing and allowing movement

Passive movement

Movement occurring at any give joint without any muscle contraction

Eccentric contractions

Muscle lengthening under active tension and occur when the muscle gradually lessens in tension to control the descent of the resistance

Actin and myosin

Muscles contractile proteins

Synergist

Muscles that assist in the action of an agonist but are not necessarily prime movers for the action, known as guiding muscles.

Muscle spindles

Primarily in the muscle belly between the fibers, are sensitive to stretch and rate of stretch. Respond by contracting the muscle.

Henneman's Size Principle

Principle that explains order of motor recruitment

All or none principle

Regardless of the number involved, the individual muscle fibers within a given motor unit will fire and contract either maximally or not at all.

Force-velocity relationship

Relationship that explains why you should train slower for strength development

Delayed onset muscle soreness

Something you experience after unaccustomed exercise

Muscle spindle

Specialized sensory organ that detects change in muscle length

Golgi Tendon Organ

Specialized sensory organ which inhibits the very muscle producing tension

Proprioreceptive Neuromuscular Fascilitation

Stretching technique used to gain more flexibility by having agonist muscle contract prior to stretching passively

Stabalizers

Surround the joint or body part and contract to fixate or stabilize the area to enable another limb or body segment to exert force and move

Extensibility

The ability of muscle to be passively stretched beyond its normal resting length.

Contractility

The ability of muscle to contract and develop tension or internal force against resistance.

Elasticity

The ability of muscle to return to its normal resting length following stretching.

Kinesthesis

The conscious awareness of the position and movement of the body in space

An inverse relationship, as speed of contraction velocity increases, force decreases

The force-velocity relationship for concentric contraction states:

The length of a sarcomere and force produced

The length-tension curve describes what relationship

Active insufficiency

The muscle becomes shortened to the point where it cannot generate or maintain active tension

Isotonic contraction

The muscle developing tension to either cause or control joint movement

Irritability/Excitability

The muscle property of being sensitive or responsive to chemical, electrical, or mechanical stimuli.

Stretch-shortening cycle

The phenomenon that explains why you can jump higher if you squat prior to take off

Proprioception

The subconscious mechanism by which the body is able to regulate posture and movement by responding to stimuli originating in the proprioceptors embedded in the joints.

Active insufficiency

This insufficiency occurs when muscle position is too shortened and force development declines

Force couples

This occurs when two or more forces are pulling in different directions on an object causing the object to rotate about its axis

Eccentric

Type of contraction where strongest?

Dynamic contractions

Varying degrees of active tension in the muscles are either causing the joint angles to change or controlling the joint angle change that is caused by external forces.

Recruitment and frequency of firing

What are 2 neural strategies to increase force produced

Isometric or isotonic.

What are the 2 classifications of muscle contraction?

Irritability/Excitability Contractility Extensibility Elasticity

What are the four properties of skeletal muscle tissue related to its ability to produce force effecting movement about joints?

Concentric or Eccentric

What are the to classifications of an isotonic contraction?

Can be used to initiate or accelerate the movement of a body segment, to slow down or decelerate the movement of a body segment, or to prevent the movement of a body segment.

What can muscle contractions be used for?

Static - no movement at joint

What is isometric?

Contractility

What is one characteristic unique to muscle tissue?

Causes motion

What is the motion of a concentric contraction?

Controls motion

What is the motion of an eccentric contraction?

Prevents motion; pressure (force) applied but no resulting motion

What is the motion of an isometric contraction?

All-or-none principle

When a motor unit is activated all muscle fibers within that unit will fire either maximally or not at all

Stretch-shortening cycle

When a muscle is suddenly stretched, resulting in eccentric contraction that is followed by a concentric contraction of the same muscle.

Responds by developing tension.

When an appropriate stimulus is provided for the property of irritability/excitability how does it respond?

It is relaxed

When doing a bicep curl, during the upward phase, what is the triceps doing?

Concentric contraction

When doing a bicep curl, the upward movement phase requires what type of contraction from the biceps?

Biceps brachii - contracting muscle (isometric) Triceps brachii - relaxed

When holding the arm in a bicep curl what is happening to the biceps brachii and triceps brachii?

Biceps brachii - relaxed Triceps brachii - contracting muscle (isometric)

When holding the arm in an elbow extension what is happening to the biceps brachii and triceps brachii?

Contraction

When tension is developed in muscle as a result of a stimulus.

Isometric contraction

When tension is developed within the muscle but the joint remains constant.

Force Couple

When the middle trapezius and lower trapezius pull in a different direction but produce movement of the scapula in the same direction

Passive insufficiency

When the opposite muscle becomes stretched to the point where it can no longer lengthen and allow movement