The document discusses the muscular system and how muscles function. It describes the three main types of muscles - smooth, cardiac, and skeletal - and their different purposes. It explains how muscles contract and relax to enable movement, working in pairs as flexors, extensors, prime movers, antagonists, fixators, and synergists. It also discusses how exercise impacts the muscular system, increasing blood flow and oxygen uptake while depleting ATP stores and building up waste products.

1. Label the diagram with as many muscles as you know.
• Gluteus Maximus
• Biceps
• Triceps
• Abdominals
• Pectorals
• Quadriceps
• Hamstring
• Deltoid
• Sternohyoid
• Erector Spinea
• Trapezius
• Oblique
• Soleus
• Gastrocnemius
• Latissimusdorsi
Muscles and Movement:
Function of Muscles:
All movement happen as a result of the shortening (contracting) and lengthening
(expanding of muscles).
The muscles enable us to move our body party
Give us our individual shape
Protect and keep our organs in place
Enable us to maintain good posture
Help in the circulation of blood
Generate body heat when they contract

2. Types of Muscle:
There are 3 main types of muscles in the body. Each type has a special purpose.
Smooth or involuntary muscle: found in the bowel, the gut and internal guts.
There is no direct control of this muscle – it works automatically.
Cardiac Muscle: cardiac or heart muscle is specialized muscle that contracts
constantly and automatically. Some factors can effect the speed of the
contractions such as exercise and the release of hormones such as adrenaline.
Skeletal Muscle: skeletal muscles are the ones that can easily be seen as a shape
under the skin. Unlike smooth muscle or cardiac muscle, we can control skeletal
muscles and because of this it is sometimes known as voluntary muscles.
Muscles and Sport
Successful sporting action depends on our muscles working together to produce
skillful movement. The muscles we use depend upon the activity. For example, in
archery we use a limited number of muscles in the upper body to work very
closely together for a short period of time. In contrast, for wrestling we use most
of the muscles in the body vigorously for a longer period of time. Sometimes we
use different muscles at different phases of an activity, For example, when
throwing the javelin we use our leg muscles in the run up and our upper body for
the delivery.
How do our muscles work?
Our muscles work in different ways. There are 3 main types of muscular
contraction.
Isotonic and concentric contraction ~ muscle shorten as they contract. The ends
of the muscles move closer together. Our biceps works in this way, for example
when we do a pull up. Most sporting movement are of this type.
Isotonic and eccentric contraction ~ muscles lengthen as they contract under
tension. The ends of the muscle move further apart. Our biceps works in this way
when we lower our body from a pull up position. Plyometric exercise uses
eccentric contractions.
Isometric ~ muscles stay the same length as they contract. There is no
movement, so the ends of the muscles stay the same distance apart. Our shoulder
muscles work in this way when we pull in a tug of war. In many sporting
movements the stabilizing muscles hold parts of the body steady as other part
move.

3. How do our muscles work together?
Our muscles can pull by contracting but they cannot push. If one muscle
contracts across a joint to bring two bones together, another muscle is needed to
pull the bones apart gain. Therefore, muscles always work in pairs. We need a
large numbers of pairs to work together in different ways for even simple body
movements. Our muscles take on different roles depending on the movement we
are performing.
They work as:
Flexors – contracting to bend our joints
Extensors – contracting to straighten our joints
Prime movers – contracting to start a movement
Antagonists – relaxing to allow a movement to take place
Fixators – contracting to steady arts of the body to give the working muscle a
firm base
Synergists – reducing unnecessary movement when a prime mover contracts.
They can also fine out movement.
How do our muscles work in pair?
When a prime mover contracts, the antagonist must relax to allow movement to
take place. However, the antagonist muscle will keep some fibers contracting.
This is to stop our prime mover moving the joint so hard that the antagonists are
damaged. Sometimes this system fails, for example when sprinters are running
flat out. They may tear their hamstrings and quickly come to a painful stop.
Levers in the Body:
We move because our skeletal muscles pull hard enough on our bones to make
them move. Our muscles use our bones as levers. Levers have a hinge (or pivot),
a load and a force working on them. In our bodies, our joints are the hinges. The
lead is the weight of our body together with anything else in our hands such as a
ball, racket or dumb-bell. The force is the muscular power we use to move our
body and the object n our hand.
First class lever – the hinge is between the effort and the load (example raising
the head)
Seconds Class Levers – the load is between the koint and the effort (example
standing on your toes)
Third Class Levers – effort is between the load and the joint (example bicep curl)
How are our muscle attached to our bones?
Our muscles are usually attached to two or more different bones. The muscle
fiber ends in a strong flexible cord called a tendon. The tendon is fixed deeply
into the bone and very strongly attached. Tendons vary in shape and size. Some
of our muscle are divided up into more than one parts. They may end in two or
more different tendons, which may be fixed to different bones. When our
muscles make the bones around a joint move, usually one bone stays fixed and
the other moves. The end of the muscle that is attached to the fixed bone is called

4. the origin. The other end of the muscle is called insertion. It is attached to the
bone, which moves as the muscle contracts the insertion moves towards the
origin.
Muscle Tone and Posture
Muscle tone can be seen when muscle are in a state of slight tension and they are
ready for action. Regular training tones muscle and helps to create good posture.
In addition muscles will hypertrophy (increase in size) and develop better
endurance. Muscle tone develops by regular exercise makes daily tasks such as
shopping and gardening easier. It also helps prevent injury as good posture
reduced the strain on muscle tendons and ligaments.
How does contraction of skeletal muscles work?
Skeletal muscles contractions are stimulated by electrical signal transmitted
along motor nerve fibers that have been sent from the central nervous system
Cross-bridge are formed between the myosin and actin molecules. The cross-
bridge originate on the myosin molecule and attach themselves to the actin
muscle. Then they drag the actin molecule towards the origin of the muscle. It is
the acting molecule that is active and moves the myosin molecules, which are
fixed.
Muscle contraction and energy
Every time a cross-bridge is formed, energy is required. The energy is provided
in the form of a chemical known as Adenosine Triphosphate (AP3).
During this break down, energy is released which is used to form on cross-
bridge. Duration of the nervous stimulus will determine the duration of the
muscle contraction. The strength of the stimulus will determine the force that
the muscle contraction exerts. There is a limited quantity of ATP in the muscle
and muscle contractor continue over a long period of time. ATP has to be rebuilt
from AP2. The rebuilding of ATP is known as muscle respiration and describes in
detail Muscle Respiration.

5. Muscle Fiber
There are two types of muscle fiber slow and fast twitch.
They are physiologically different.
The amounts of fast twitch or slow twitch fibers in the muscle will determine
their suitability to certain sporting activities.
The amount of each fiber type in our muscles is also determined genetically, that
is , we are born with it.
Training will ave little effect on altering the ratio of fast twitch to slow twitch
fiber in the muscle
This is why there are people who are ‘natural’ endurance athletes. They have
greater amounts of slow twitch fiber which contracts slowly with little force but
do not tire easily.
Other people have greater fast twitch fibers and are naturally’ good at sprinting
and throwing. These fibers produce larger forces but tire quickly.
How does our body move?
Extension – our limbs straighten at a joint
Flexion – our limbs bend at a joint
Abduction – our limbs are moved away from a line down the muddle of the body
Adduction – our limbs are moved towards a line down the middle of the body
Rotation – this is a circular movement. Part of the body turns whilst the other
rest (remains still)
Circumduction – the end of the bone moves in a circle, for example swinging
your arm in a circle at the shoulder
What happens to our muscular system as we exercise?
There is an increased flow of blood to the working muscle
Muscle take up more oxygen from the blood
The muscles contract more often and move quickly
More of the muscle fibers contract
There s a rise in temperature in the muscle
Our stores of AP3 and CP in the muscles are used up
Waste products such as CO2 and lactic acids build up in the muscle
These waste products may lead to tiredness and cramp –DOMS
Our store of muscle glucose is used up
Endurance is effected
Muscle Changes and Sport
Our muscles increase in size and strength when we follow a regular strength,
training program. This is called hypertrophy. When we do not use our muscles
regularly they get smaller and weaker. This is called atrophy.

6. Muscle Breakdown and Repair
The complicated science of muscle growth, and the danger of muscle breakdown
and degradation mean that careful consideration should be given to how we
work out, what we eat to recover and what are fitness foals are
Understanding what happening
When we are working our we are causing muscle breakdown. In the aftermath of
the workout our body makes repairs to this muscle tissue.
Give the Body Repair Materials
Our body needs carbohydrates and protein in order to cope with muscle
breakdown and make the proper repairs. Too much muscle breakdown is bad. It
can cause a loss of muscle size. Swapping quantity for quality will not result in
bigger gains. Make sure the time spend working out is leading to successful
gains.