1. +
Muscle Fibre Types
And muscular contractions

2. +
Key Concepts

Muscles consist of slow-twitch and fast-twitch fibres. These
fibres are suited to certain types of physical activity and assist
with an athlete’s capacity to create forceful or sustained muscle
contractions.

Muscle contractions can be isotonic (concentric and eccentric)
and isometric

3. +
Muscle fibre types

There are two basic types of muscle fibres we have in the body

Fast twitch (2 types) and slow twitch

Most people would have about a 50:50 split of the two different
types

Each fibre is better suited to a different type of activity (based
on its intensity)

4. +
Slow Twitch (Type 1 fibre)

Red in colour

Contract slowly over a longer
period of time

Best suited to aerobic and
endurance type activities

Exert less force and can
contract repeatedly

5. +
Fast Twitch (Type 2a)

Very similar characteristics to
Slow Twitch fibres

Have the ability to contract very
forcefully over a longer period
of time

6. +
Fast Twitch (Type 2b)

While in colour

Contract rapidly over a shorter
period of time

Best suited to anaerobic and
high intensity activities

Exert great force in bursts of
power and speed

8. +
Athletes and their fibre types

9. +
Types of muscle
contractions

10. +
Overview

There are three types of muscles contractions classified by the
movement they cause

Isotonic

Isometric

11. +
Isotonic

The most common type of contraction

Occurs when there is a change in muscle length as tension is
developed

Muscle is shortening = isotonic concentric

Muscle is lengthening = isotonic eccentric

12. +
Isometric

This type of contractions is characterised by the muscle
contracting without causing movement.

Example: Holding your body in a squatting position

It is quite difficult to maintain this contraction for a long period of
time