Know your muscles - Women's Running

Know your muscles

Author: Juliet McGrattan

Read Time:   |  February 2, 2015



The body has about 700 different muscles. There are three types. Visceral muscle, sometimes called smooth muscle that is found inside organs such as the bowel and stomach – we don’t have any control over this type of muscle. Cardiac muscle, found only in the heart, and skeletal muscle, responsible for any movement we make from talking to sprinting.



Skeletal muscle is made of long fibres and there are two types: Type I, otherwise known as slow twitch fibres, contract slowly and take a long time to tire so they give you stamina and endurance. Type II fibres are fast twitch, contract quickly, tire rapidly and are used for jumping and sprinting. All muscles contain both types of fibres but your personal mix of slow and fast twitch is largely inherited and determines to some extent whether you’re best suited to sprinting or long distance running.

You can build up both types of muscle fibres with different types of exercises but the jury’s still out on whether you can convert one type of fibre into another.

Muscle fibres are packed with mitochondria – the ‘power house’ of the cell that converts glucose into energy. There are blood vessels and nerves running through the bundles of fibres and everything is held together and protected by a tough sheath. Muscles attach to bones by tendons where the sheath forms a cord of strong collagen tissue.


Muscle injury

When you pull or strain a muscle some of the muscle fibres get torn. The small blood vessels between the fibres may tear too resulting in a bruise. A strained muscle needs to be protected, rested, iced, compressed (with an elastic bandage) and elevated (PRICE). If you follow this formula and take painkillers but it isn’t helping then see your GP.



Delayed Onset Muscle Soreness is the reason why you can’t get down the stairs two days after a long run. It used to be blamed on a build up of lactic acid but it’s now believed to be due to micro tears and trauma (damage on a very small scale) of muscle fibres. It usually settles after three days but light exercise and warm baths can ease the discomfort.


Muscle recovery

Muscles need to be rested to allow time for them to recover and adapt to the increasing demand you’re placing on them when you train. Muscle glycogen (energy) stores need to be replenished, lactate and other waste products cleared and any torn muscle fibres repaired. Don’t skip rest days – your muscles need them. Foam rolling, massage, stretching and compression garments are some of the ways people try to speed up and improve their muscle recovery. A good supply of protein is needed for muscle growth and repair so make sure you include plenty in your diet especially if you are training or racing hard.


Juliet McGrattan

Health expert, author, keen runner and busy mum

Meet the team

We use cookies to give you a better experience on By continuing to use our site, you are agreeing to the use of cookies as set in our Cookie Policy.

OK, got it