Home - 8-12 years - Micro-breaks


Have you ever wondered how you stand, or how you move your body, or how you bend your knees or elbows, or how you breathe?
Well, it’s all thanks to your muscles, among other things.

What are muscles?

l How they function? l Activities and postures

Micro-breaks. Exercises that can be done in class. 5 minutes every hour.


Rotate shoulders




Open and close hands


Open and close legs


Leg press


Saying yes


Saying no


I don't know






Wrist twist


The aeroplane

What are muscles?

We humans have over 150 muscles.

Muscles are body tissues or organs (human and animal) known for their ability to contract and stretch.

There are two types:
  • Striated muscles which cover the skeletal structure.
  • Smooth muscles which are in the skin, blood vessels, digestive tract, respiratory tract and urogenital apparatus.


How they function

The movements of the bones of the skeleton are possible thanks to the contraction of the skeletal muscles, which are connected to the bones by tendons.

That is, contraction of the skeletal muscles is what causes the different skeletal bones and cartilages to move.

The skeletal muscles make up most of the body mass of vertebrate animals.

Movement of the muscles is controlled by the nervous system.

Curiously enough, the heart is a muscle.

We say a muscle is healthy when it can be fully contracted and extended.

To function properly, a muscle must be flexible, elastic and painless, that is, it should not hurt when we make it work.

When we make our muscles work, either when moving them or when keeping them contracted,
our body reacts by changing the metabolic cycle, the supply of oxygen and the expulsion of toxins into the blood.

If we work them too hard our muscles let us know, they protest: we get stiff, feel tired and start to ache.

This is called fatigue or muscle soreness, or torticollis (stiff neck) and it can also be caused by bad posture.

Most skeletal muscles are made up of two types of fibres:

  • Fast contraction fibres, dark in colour, contract rapidly and generate lots of power.
  • Slow contraction fibres, paler in colour and very strong.


Activities and postures

At school, in the office, in the car, in the cinema, when eating, on the sofa watching television, at the computer, when reading, etc.

Muscles that get adequate exercise react to stimuli quickly and powerfully and are said to have muscle tone, i.e. they are toned.


When we over-exert them, they can increase in size. This is called hypertrophy, and means that each muscle cell has grown.

However, when our muscles are inactive for a long time, atrophy occurs, which means that they have become weak, sick or paralysed.

It is important to avoid bad postures which, minute after minute, hour after hour and day after day can adversely affect our muscles.
For this reason we’re suggesting a number of exercises that could be called "muscle micro-breaks".



Centre de Salut de la Columna Vertebral (CSCV) (Health Centre for the Spine)