1. Slow and Fast twitch Muscle Fibre types
Topic 4

2. Types of Muscle Fibers:
Slow Twitch: (type 1)
*smaller in diameter
*reddish color
*use aerobic respiration for ATP supply
*contain more mitochondria
*fire slowly, but take long to fatigue.

3. Slow Twitch
The slow muscles are more efficient at using oxygen to generate more fuel (known as ATP) for continuous, extended muscle contractions over a long time.
They fire more slowly than fast twitch fibers and can go for a long time before they fatigue. Therefore, slow twitch fibers are great at helping athletes run marathons and bicycle for hours.

4. Fast Twitch: used for short explosive movements, stop and go sports.
Type IIA:
*large diameter
*white in color
*less mitochondria
*uses both anaerobic and aerobic energy transfer
Type IIB:
*same physical characteristics as Type IIA, but strictly uses the glycolytic anaerobic system.

5. Fast Twitch: used for short explosive movements, stop and go sports.
Fast twitch fibers are responsible for the speed of muscular contraction, and a fast twitch response is the ability of a muscle to rapidly contract to a specific distance over a short period of time.
Therefore, any training program that conditions your muscles to go from a state of complete relaxation to an immediate state of contraction is a speed training program.

6. Fast Twitch: used for short explosive movements, stop and go sports.
Because fast twitch fibers use anaerobic metabolism to create fuel, they are much better at generating short bursts of strength or speed than slow muscles. However, they fatigue more quickly.
Fast twitch fibers generally produce the same amount of force per contraction as slow muscles, but they get their name because they are able to fire more rapidly.
Having more fast twitch fibers can be an asset to a sprinter since she needs to quickly generate a lot of force.

7. Mitochondria
Mitochondria are energy-producing cells, which create adenosine triphosphate or ATP for short.
ATP is your body's essential chemical fuel and is necessary for all energetic reactions. Slow-twitch fibers have a high number of mitochondria, which provide them with an almost limitless amount of energy.
Combined with their high blood supply, slow-twitch muscle fibers are ideally suited to long, endurance-type activities.
On the other hand, fast-twitch fibers have considerably fewer mitochondria and, as a result, fatigue far quicker than their slow-twitch counterparts.

8. Blood Supply- Slow Twitch
Slow-twitch fibers have a very good blood supply -- so much so that they are often referred to as red fibers.
This plentiful supply of blood ensures that slow-twitch fibers receive a large amount of oxygen, which allows them to work for a long time before becoming fatigued

9. Blood Supply- Fast Twitch
In contrast, fast-twitch fibers have a relatively poor blood supply and are subsequently referred to as being white in color.
The lack of blood results in relative oxygen restriction, so fast-twitch fibers tend to fatigue much faster than the better oxygenated slow- twitch fibers.

10. Slow Twitch- Diameter and Force Production
Slow-twitch fibers are much smaller in diameter and are far less powerful.
While they cannot generate large amounts of force, they can generate low amounts of force for long periods of time.
They have very little potential for hypertrophy, and are best suited to endurance activities such as walking and cycling long distances.

11. Fast Twitch- Diameter and Force Production
Fast-twitch muscle fibers have a larger diameter than slow-twitch fibers. They also have the greatest hypertrophy (growth potential).
The larger the cross-sectional size of a muscle fiber, the greater the amount of force it will be able to produce.
Fast-twitch fibers are best suited to high-intensity, but short-duration activities such as lifting heavy weights or sprinting.

12. Slow and Fast Twitch Preferred Fuel Source
Slow-twitch muscle fibers rely on oxygen as their main energy source.
Fast-twitch muscle fibers rely on ATP and glycogen as their main energy source.
As ATP sources can be rapidly depleted, lactic acid is a by product of the breakdown of glycogen, fast-twitch fibers can only be active for a short period of time.