All muscle tissue in the body is made up of two different types of muscle fibers, both of which you can see if you were to look at a cross-section of muscle tissue under the microscope. These are red muscle and white muscle.
White muscle fibers tend to be smaller than red muscle fibers and can be found in the heart, tongue, esophagus, blood vessels, intestines, and other parts of the body where speed or endurance isn’t as important as it is in large muscles that work hard during exercises like the quadriceps or gluteus maximus.
What is White Muscle (Cardiac)?
Found in internal organs (like your heart), as well as in your esophagus, stomach, intestines, etc. These are called white muscles because they aren’t red when cut. They’re also smooth to touch. Contractile tissues within these muscles move food through our guts and blood through our hearts. These are slow-twitch muscles – meaning they can work for long periods without fatiguing. Think of a marathon runner vs a sprinter.
The white muscle is located in the center of your body. This muscle is responsible for moving food through your digestive system. Your red muscle is located on the outside of your body. This type of muscle is used to move blood throughout your body.
What is Red Muscle (Skeletal)?
Skeletal muscles have a red hue because they contain an oxygen-storing protein called myoglobin. Myoglobin helps muscles access oxygen so they can keep contracting to produce force. This is why your biceps get sore after lifting weights; those tiny fibers are storing oxygen for use during future contractions.
In addition, skeletal muscle cells have many nuclei, which help coordinate the contraction of all of their constituent fibers. The more nuclei you have, the stronger you are—think bodybuilders with bulging biceps. The downside of having lots of nuclei is that it takes longer for muscles to repair themselves after exercise.
That’s why it’s important to give yourself plenty of time between workouts if you want to make progress toward increasing strength or endurance in any particular muscle group.
How do they Differ?
Both red and white muscle tissue is capable of contracting. Red muscle is responsible for endurance, while white muscles are responsible for strength. This difference stems from differences in fiber composition between white and red muscles. More mitochondria in red muscle allow it to use oxygen more efficiently than white muscle, allowing it to contract slowly but with a greater force generation potential.
Your white muscle is much larger than your red muscle. Your red muscle is about 1/10th the size of your white muscle. Your red muscle is located inside your heart. Your white muscle is located outside your heart.
Cardiac vs. Skeletal
Cardiac muscle is found only in your heart. Skeletal muscle makes up everything else. Your body contains all kinds of muscles, but those two categories—cardiac and skeletal—make up 95 percent of all muscle mass in your body. Their function is slightly different, but if you’re trying to lose weight safely, that shouldn’t matter to you. Both types will help you shed fat whether you know it or not.
The difference between red and white muscles is based on their history. The red designation comes from myoglobin, a protein that helps transport oxygen in your blood. Myoglobin makes your muscle look red—and gives it a higher capacity for generating energy.
This means you can work out longer before fatigue sets in. That’s great news if you’re looking to build strength and endurance, but not so great if you want to lose weight (more on that later). For now, let’s focus on building strength with red muscle by lifting weights.
|Basic Terms||Red Muscle||White Muscle|
|Fatigue||Show less fatigue||Show fast fatigue|
|Accumulation||Low accumulation of lactic acid||High accumulation of lactic acid|
|Power||Low power||High power|
|Work||Suitable for performing prolonged work||Suitable for performing short-time work|
|Alternative name||Slow-twitch muscles||Fast-twitch muscles|
|Example||Extensor muscles of the human||Eyeball muscles|
Both red and white muscle tissue plays a key role in the movement, but their distinct physical composition sets them apart. What’s more, even if your body has a higher ratio of one over another, neither type is more important than the other: Both perform critical roles. Understanding how they differ will help you develop a more well-rounded understanding of how your body works as a whole. Read on to learn more about red and white muscle tissues.