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Transcript of Muscles
Structures, Functions and Types
Origin-Insertion and the contraction
Skeletal muscles are attached to bones and their contractions are responsible for moving the body.
These contractions are initiated by impulses in the motor neurons to the muscle and is usually under voluntary control.
These muscles are linked to bone by connective tissue called tendons.
Types of muscle
Lets label the origin and insertion points
In order for muscles to create movement they must be attached to bones. Muscles are attached to bones with a strong fibrous material called tendons at the end of each muscle.
The end of the muscle that is attached to the bone that does not move is call the
The point of attachment on the bone that does move is call the
Muscle Fiber Types
There are different types of muscle fibers that make up skeletal muscles. Some fibers can reach maximum tension more quickly than others. Based on this difference the fibers are divided into two categories.
Fast Twitch- (FT or Type II) also called white fibers based on their microscopic appearance.
Type II fibers can be further broken down into
Type IIa (FTa)
Type IIx (FTx)
Slow Twitch- (ST or Type I) also called red fibers based on their microscopic appearance.
Lets look under the microscope
A cross section of muscle tissue
Fuel source- Oxidative system
These fibers have high aerobic endurance
Most often used in low intensity endurance activities and day to day activities that require little muscular force
Fuel source- Glycolitic system
These fibers fatigue more quickly
Type IIa mostly used during high intensity endurance events (400m run)
Type IIx mostly used during highly explosive movements (100m dash)
A product of the breakdown of nutrients in the body
The result is the production of a molecule known as ATP (adenosine triphosphate)
There are two systems or pathways for creating energy from nutrients.
Breaks down carbohydrates (glycogen and glucose)
This process takes place without the presence of oxygen
This process when used at high intensity can cause lactic acid to accumulate in the blood. This point is known as the anaerobic threshold.
Isotonic contraction (dynamic)
Isokinetic contraction (dynamic)
Plyocentric contraction (dynamic)
Isometric contraction (static)
The primary source of energy
Process called oxidative phosohorylation is used to resynthesize ATP (energy)
The Kreb's cycle is used to break down many fuel sources, such as; glucose, fat molecules and protein
Static or Dynamic
Contraction through movement.
As changing joint angles and speed vary, so does the amount of tension need for the muscle contraction.
The muscle can work at the same rate through out the motion.
A hybrid contraction as the muscle performs an isotonic concentric contraction from a stretched position.
A contraction in which there is no visible change in the length of the muscle. This occurs when the muscle is working against a load that is greater than the muscles capability.
Muscle contracts at varying
speeds dependent on the
make the tension
This type of training has shown to increase jump height more than traditional strength training
There is no movement
Concentric vs. Eccentric Contractions
Muscles can only contract in one way (by shortening). However muscles can contract as they are being forced to lengthen.
A contraction in which the muscle lengthens during the movement.
A contraction in which the muscle shortens as it goes through the range of motion
Let's think of some more examples
Let's think of some more examples
Ratio of Slow-Fast Twitch Fibers
Muscle Fiber Types in various athletes