Download Muscular System

1.2.4 - A healthy, active lifestyle
and your muscular system
Antagonistic Muscles
• Because muscle can only pull when they
contract they work in pairs to create a
range of movement around a joint. When
muscles work in pairs they are said to be
working antagonistically.
• The Bicep and Triceps work as a pair to
flex and extend the arm.
Types of Muscles
The Involuntary Muscles (smooth)
• Involuntary muscles work automatically and
cannot be consciously controlled (for example
The Cardiac Muscle
digestion).

This muscle contracts automatically
and at regular intervals. (Heart)


The Voluntary Muscles
(Skeletal)
These 600 muscles, made
of long fibres, are attached
to the bones and let us
move around.
We control these voluntary
muscles.* (Biceps etc)
When the arm bends the
movement is called Flexion.
When the arm straightens the
movement is called Extension.
Movements of the body
1.Extension
2.Flexion
3.Abduction
4.Adduction
5.Rotation
Muscle Contraction (Isometric)

• When muscles are
working but stay the
same length this is
called isometric
contraction. There is
no movement.
• What is happening
in this press up?


There is isometric contraction
of the back muscles.
They are working to stabilize
the body.
The arms can now work effectively
to complete the exercise.*
Muscle Contraction
(Isotonic)
• There are two types of Isotonic
contraction.
• When a muscle shortens as it
contracts this is called a
concentric contraction.
• An example of this would be
the bicep when lifting the
weight while doing a ‘curl’.
• When a muscle lengthens
while still being tense this is
called an eccentric contraction.
• This happens as you lower the
weight under control while
doing a curl. *
Effects of exercise on the
muscular system
Short term effects
• The body combines glycogen and oxygen in the working muscles to
make energy. A supply of blood is needed to continually replenish
oxygen and glycogen stores.
• As we increase intensity of exercise we need to be able to increase
the supply of oxygen rich blood also.
• As we exercise our muscles make waste products. These are also
carried in the blood to be removed.
• Our muscles can work aerobically (with oxygen) for long periods of
time as long as the intensity is not to high.
• As we increase intensity the body finds it harder to cope with
delivering all the oxygen and nutrients, converting it into energy and
getting rid of waste products as well.
•
During anaerobic respiration another waste product is
produced called 'lactic acid'. This waste product builds
up in the muscles until eventually it is not possible to
continue as lactic acid causes muscles to ache and can
cause cramp.
• When you exercise at or over 75% of your maximum
work rate lactic acid builds up in the muscles.
• Regular exercise and training help your muscles improve
their ability to produce energy and the blood vessels in
the muscles become more efficient so that they can cope
with the process better.
Long term effects.
• The whole muscular system benefits from regular exercise. This
includes the involuntary muscles (internal muscles around our
organs that keep our body functioning) and voluntary muscles
(muscles we use to create movement). As well as the skeletal
muscles contracting to create movement
• Increased muscle size - hypertrophy
• When you train muscles using the principle of progressive
overload, the tiny muscle fibres are pulled apart.
• The body repairs these damages when we rest and build the fibres
back slightly stronger.
• As muscles repair the resulting increase in
muscle mass is known as muscle
hypertrophy.
• Thicker muscles can contract more strongly. So
regular exercise increase muscle size and
strength.
• If you stop training then muscle reduce in size
again through the principle of reversibility. This
is called muscular atrophy
• Using various training methods will allow
you to effect how the muscle grows. It is
important to know how different training
can result in increased
• Muscle size,
• Muscle strength,
• Muscle power (as a result of strength x
speed)
• Muscular endurance
• If you stop training then muscle reduce in
size again through the principle of
reversibility. This is called muscular
atrophy
Rest and recovery
• If you do not allow your body long enough to
recover properly you could risk injuring yourself
through overuse.
• After an intense training session and may take
up to 48 hours for the muscle to repair properly.
• As your body gets used to training your body
can become more efficient at repairing and it can
reduce the time it takes to recover fully.
Diet and drugs
• Your muscles are made up of protein. By eating
a high protein diet you can speed up the rate at
which your body can build and repair
muscle; shortening your rest and recovery
time.
• Steroids stimulate the body to produce muscle
proteins at a faster rate. This also speeds up
the time it takes to build and repair
muscles. This is why some athletes use illegal
drugs in sport and take the risks of being
caught.