Fast fibers Fast fibers have low resistance to fatigue. have twitches with a very brief contraction phase. have many mitochondria. have low resistance to fatigue and quick twitches. rely on aerobic metabolism.

Fast fibers

a) have low resistance to fatigue.

b) have twitches with a very brief contraction phase

Explanation:

Fast fibers are one of the types of skeletal muscle fibers.

Characteristics of fast muscle fibers are:

a. They generate a large amount of energy

b. They are more prone to fatigue or tiredness hence, their low resistance to fatigue.

c. They generate twitches with a very low contraction phase.

d. The diameter or size of each fast muscle fibers is very large.

e. They generate a lot of tension

f. They have low number of mitochondria in them.

g. They have a medium ( average) - low number of red protein myoglobin and capillaries present in them.

h. The oxidative capacity of a fast muscle fibers is at a lower level

I. Fast muscle fibers are activated in activities such as jumping, sprinting, strength training e.t.c.

• have twitches with a very brief contraction phase

Explanation:

There are different types of muscle fibers in the body and their classification is based on how they produce energy. They are generally classified as being either slow-twitch or fast-twitch.

The Fast muscles is also known as fast-twitch or type II muscles fibers.

Here are things to know about fast-twitch, or type II, muscle fibers:

• can be further classified based on if it use oxygen to help convert glycogen to ATP or if rely on ATP stored in the muscle cell to generate energy as fast-twitch IIa and IIb respectively.

• have a high threshold in that they come in for emergency support and are deployed, recruited or activated only when the force of work demands are greater than that which the slow-twitch fibers can meet.

• the bigger the fiber the shorter time it takes to reach peak force and then generate higher amounts of force to what a slow-twitch fibers can afford.

• generate twitches with a very low contraction phase.

• diameter or size of fast muscle fibers is relatively large thus accounting for the size and definition of a particular muscle

• can generate more tension (force), but are quicker to fatigue relative to slow-twitch fibers.

• also known as “white fibers” just because they do not contain much blood linking to the low number of mitochondria in them.

This from the question above fast fiber have twitches with a very brief contraction phase.