Difference Between Red and White Muscle

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Red and white muscles are the skeletal muscles in our body and they perform some critical functions in the body. At Vedantu, we have created a summary of the difference between red and white muscle for an easy understanding of the students. Let’s first understand what these muscles are. 


There are almost 600 muscles in a human body and these are classified into three categories; skeletal muscles, cardiac muscles, and smooth muscles. The musculoskeletal system of the body has two basic components: the muscles (musculo) and the skeletal structure upon which these muscles are attached. These skeletal muscles can be categorized into red muscles and white muscles.


Red Muscles

Red muscles are red because of the presence of dense capillaries that are rich in myoglobin and mitochondria. One of the main difference between red and white muscle fibres is the colour which is deep red for red muscles because of myoglobin which is present in the sarcoplasm (cytoplasm) of the muscle fibre. The myoglobin present in red muscles binds oxygen and stores it as oxymyoglobin in the red fibres. During muscle contraction, oxymyoglobin releases the oxygen required. A good example of red muscles is the extensor muscle.


White Muscles

White muscles have a lesser amount of myoglobin and mitochondria and hence appear whitish. An example of white muscle is the eyeball muscle.


Let’s look at the red and white muscle difference in detail below


Criteria

Red Muscles

White Muscles

Presence of Mitochondria

They are more in number in the body

Lesser in number than they are in red muscle

Appearance

Red muscles are thinner

White muscles are thicker than red muscles

Capillary bed

Capillary bed is denser

It is less dense

Contraction rate

The contraction rate of red muscles is slower than in white muscle

The contraction rate is faster than that of red muscles

Sarcoplasmic Reticulum (SR)

They have a lesser amount of SR than white muscle

They have  more SR than red muscle

Fatigue rate

Red muscles can perform aerobic oxidation without collecting a lot of lactic acids. This helps the red muscles to contract for a long period

White muscles perform anaerobic oxidation and in the process, they accumulate more lactic acid than the red muscles. This leads to fatigue in the muscles after a short period of contraction.

Oxygen utilization

Red muscles use more oxygen than white muscles and this is one of the reasons why they are used in strenuous activities like exercise.

White muscles use a lesser amount of oxygen than the red muscles

Energy generation

They rely only on oxygen to generate energy and are thus also called slow-oxidative muscles.

They are rich in glycogen and enzymes of glycolysis which gives them the required energy.

Twitch-fibres

They have slow-twitch fibres that contract slowly for a long time without fatigue

They have fast-twitch fibres that contract faster for a short period and get tired soon.

FAQ (Frequently Asked Questions)

Q1. Why are the Red Muscle Fibres Called Slow-twitch Fibres?

Ans: The twitching speed is one of the main difference between red and white muscle fibres. Red muscle fibres are called slow-twitch fibres as they contract slowly for a long time without experiencing any kind of fatigue. An example of red muscles is the extensor muscles. This is one of the reasons why red muscles are put to use during strenuous activities like exercising. Red muscle fibres get their energy from fat and glycogen by using oxygen. This is aerobic energy generation and since it is a lengthy process, the muscles contract slowly. Red muscles have a high tolerance for fatigue and do not tire out easily. 

Q2. Why are the White Muscle Fibres Called Fast-twitch Fibres?

Ans: Unlike red muscle fibres, the white muscle fibres can contract faster and this is why they are called fast-twitch fibres. These muscles have low myoglobin and low oxygen content. White muscles therefore do not depend on oxygen for their energy but get it from glycogen. This anaerobic energy generation process is faster and it helps the white muscle fibres to contract faster and stronger. White muscles tire out easily and this is the reason why the body activates them at the last.