💪 How Do Muscles Work?
4th Grade 🏃 Health & PE
Muscles move your body by getting shorter (contracting) and pulling on your bones.
Pull, never push
Muscles can only pull. That is why they work in pairs. When you bend your arm, the biceps on the front contracts. To straighten it, the triceps on the back pulls.
Three kinds
Skeletal muscles move your bones and you control them. Smooth muscles, in your stomach for example, work on their own. The heart is a special muscle that beats your whole life.
More than 600
You have more than 600 muscles. The biggest is the gluteus maximus (in your bottom!). Exercise and protein help muscles grow strong.
Quick quiz
What do muscles do to move bones?
Which muscle bends your arm?
About how many muscles do you have?