Muscle actions 10.4

Muscle Actions

Neural stimulation can lead to three types of muscle actions

1. Concentric action

2. Eccentric action

3. Isometric action​

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Concentric action

• ​This occurs when a muscle shortens in order to overcome a load

• For example, the bicep muscle experiences concentric action during the upward phase of a bicep curl.

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• This occurs when the muscl​e is overcome by a load and is forced to lengthen

• This occurs during the downward motion of a bicep curl.​

• Can also be thought of as the ​deceleration of joint motion

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Eccentric Action

• Occurs when a muscle generates force against a resistance but no movement takes place.

• Think of flexing a muscle and holding it.

• Many postural muscles fire isometrically to keep the body upright.​

Isometric Action

​The "opposite muscle"

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This muscle is the one that is being stretched while the agonist contracts.​

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Antagonist Muscle

The muscle that is initiating the desired movement.

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The "Main Mover"​

​Agonist muscle

Agonist and Antagonist

During a bicep curl, the main movement is flexion of the arm. This is achieved by the ​contraction of the bicep.

Biceps

​While the bicep is contracting the tricep is relaxing and stretching. ​

Triceps

Example of Agonist vs antagonist

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​Muscle Fiber types

• ​There are two types of muscle fibers

• Fast twitch (Type II) and slow twitch​ (Type I)

• Fiber types are differentiated by their metabolic and contractile properties​

Fast Twitch (Type II)

• Fast twitch fibers have the ability to generate rapid, powerful muscle actions.

• Type II fibers' speed of shortening is three to five times faster than that of slow twitch.

• Predominately used in anaerobic movements such as, volleyball spike or a tennis serve.​

• These fiber types tend to fatigue easily.​

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Slow Twitch (Type I)

• These fiber types are typically involved in energy production for prolonged aerobic activities.

• For example, aquatic exercise, long distance running, and stationary cycling will all involve the use of slow twitch muscle fibers.

• These are described as fatigue resistant​.

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Fast Twitch vs. Slow twitch

There are MORE THAN 600 muscles in the human body

They fall into THREE main categories

Autonomic Nervous System

• Smooth

• Cardiac

Somatic

These muscles are VOLUNTARY. The brain sends a signal down the spinal cord to the nerve that controls the muscle and the muscle contracts

The Skeletal Muscle

• MUSCLE FIBER

  ENDOMYSIUM- COVERING

• FASCICLE (BUNDLE)

  PERIMYSIUM- COVERING

• BELLY (BULK OF THE MUSCLE)

  EPIMYSIUM- COVERING

• TENDON

Multiple Choice

How many TYPES of muscles are in the human body?

• 2

• 3

• 4

• 5

Multiple Choice

Which of these muscles types have VOLUNTARY contractions?

• Cardiac

• Skeletal

• Smooth

Multiple Choice

Which of these coverings surrounds the individual muscle fiber?

• Endomysium

• Perimysium

• Epimysium

Multiple Choice

Where would you find the perimysium?

• Around the belly of the muscle

• Around one of the fascicles

Multiple Choice

Is this an Eccentric, Concentric or Isometric Contraction?

• Eccentric

• Concentric

• Isometric

Multiple Choice

Pick the isometric contraction

Isometric Contraction

In this type of contraction the muscle contracts but does not shorten

Multiple Choice

How many skeletal muscles are in the body

• 206

• 405

• over 650

• over 1000

Multiple Choice

Which is considered the "main mover"

• Agonist muscle

• Antagonist muscle

• Smooth muscle

• Cardiac muscle

Multiple Choice

What type of muscle is considered the opposing muscle during a given movement

• Agonist muscle

• Antagonist muscle

• Smooth muscle

• Cardiac muscle

Match

Match the agonist muscles with their antagonist muscle

• Bicep

• Quadricep

• Latissimus Dorsi

• Gastrocnemius

Tricep

Hamstring

Pectorals

Tibialis Anterior

• Tricep

• Hamstring

• Pectorals

• Tibialis Anterior

Multiple Choice

Which of these activities would require predominately Fast twitch muscle fibers

• Running a Mile

• Cycling

• Swimming

• 100m dash

Multiple Choice

Which of these activities would require predominately slow twitch muscle fibers

• Volleyball spike

• Tennis serve

• 100m dash

• Marathon