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 digestion).

The Cardiac Muscle 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.Flexion3.Abduction4.Adduction5.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.