Exercise Science: Muscular System

Muscular System

Anatomy and Functions

Objective

Students will be able to describe the foundational anatomy and functions of the gross and microscopic composition of muscle. In this unit, we will explain the theory of muscle contraction and consider various types and functions of muscle fibers.​

Exercise Science

Lines the internal organs such as the intestines and stomach

Also involuntary muscle

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Smooth Muscle

Composes the walls of the heart.

Involuntary muscle and therefore not subject to conscious control​

Cardiac Muscle

three types of muscle tissue

Skeletal Muscle

​Attaches to the skeleton via tendons to produce bodily movement.

Skeletal muscle is voluntary, meaning one can consciously control it.​

Multiple Choice

Which type of muscle tissue lines the internal organs such as the intestines and stomach?

• Cardiac Muscle

• Smooth Muscle

• Skeletal Muscle

Multiple Choice

Cardiac Muscle

• Attaches to the skeleton via tendons

• Lines the stomach and intestines

• Composes the walls of the heart

Multiple Choice

The only voluntary muscle tissue that produces bodily movement

• Cardiac muscle

• Smooth muscle

• Skeletal Muscle

Introduction to skeletal muscle

• Under voluntary control​ of the nervous system

• Accounts for 36%-45% of the total body weight

• Over 650 different muscles

• Most plentiful tissue in the human body​

Introduction to skeletal Muscle cont...

To enable the body to move, the muscles usually work together in muscle groups.

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Most of the muscle groups in the trunk and extremities work in opposing pairs​

​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

Open Ended

Can you try to name another pair of muscles that are agonist and antagonistic to each other?

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

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

Match

Match the following

• Concentric contraction

• Eccentric contraction

• Isometric contraciton

Muscle shortens

Muscle lengthens

Muscle does not shorten or lengthen

• Muscle shortens

• Muscle lengthens

• Muscle does not shorten or lengthen

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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

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

Open Ended

Tell me the most interesting thing you learned about muscles.