How do muscle fibres shorten?
Muscle fibres contain tiny rod-like structures that overlap. When the fibre receives a nerve signal that tells it to contract, these rods slide over one another, making the fibre shorter. As the fibres shorten, the whole muscle contracts. All the fibres do not contract together. The harder the muscle needs to pull, the greater the number of fibres that will contract at the same time.
Can I make my muscles grow?
Muscles react to frequent exercise by growing more muscle cells, or fibres, making the muscle thicker and more bulky. The more fibres there are in a muscle, the stronger it will be. This explains why athletes who take constant exercise develop very large muscles.
How many muscles do I have?
You have about 650 muscles in your body. There are more than 50 muscles in your face alone.
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