HOW MUSCLES WORK?
Muscles work by contracting and expanding. When it tightens it is called contraction. When it loosens the muscle relaxes. Your nervous system tells the muscles when to contract and expand.
WHAT ARE MUSCLES
Muscles are made of bundles of thin elastic strands called fibres. The muscle fibres are made of proteins. There are two types of muscle fibres. You have slow twitch and fast twitch. Fast-twitch muscle fibres contract quickly. These fibres give you bursts of power for things likes sprinting.
Slow-twitch muscle fibres give you endurance. When you run a long way, your slow-twitch muscle fibres do most of the work. Some kinds of muscle have both fast-twitch and slow-twitch fibres.
DIFFERENT KINDS OF MUSCLES?
There are three types of muscle called skeletal, smooth, and cardiac. Each type of muscle has a different job to perform.
Your skeletal muscles are attached to your bones. These muscles contract and relax to give movement to your bones. Usually you have to think about making these muscles contract.
Smooth muscles move automatically. You do not have to think about these muscles to make them work. Your digestive system is surrounded by smooth muscle. Smooth muscles push food through your digestive system.
Your biggest blood vessels are surrounded by smooth muscle to make them strong. Your cardiac muscle makes your heart beat. You do not have to think about moving your cardiac muscle as cardiac muscles contracts automatically.