What are the Functions of the Muscles in the Human Body?

J.M. Densing

The muscles in the human body perform several important functions. Their primary function is movement, both voluntary and involuntary, and they also support the body, helping to maintain posture. Healthy, strong muscles also stabilize the body's many joints and determine overall body strength. An additional function is to generate heat as a byproduct of other processes.

Maintaining strong muscles is beneficial for overall well-being.
Maintaining strong muscles is beneficial for overall well-being.

The most obvious function of muscles is movement. Voluntary movement involves a conscious effort on the part of the individual, and examples include walking, bending, twisting, and lifting. It also includes fine motor movements, such as writing or playing an instrument. The type of muscle usually responsible for voluntary movement is called skeletal; it is striated muscle that has a banded or striped appearance under a microscope. Skeletal muscles are attached to the bones and produce locomotion by contracting, or tightening, and relaxing.

Skeletal muscles maintain posture, even while sitting.
Skeletal muscles maintain posture, even while sitting.

The other type of movement is involuntary, and it occurs automatically. Examples include breathing, the movement of food through the digestive system, and the beating of the heart. These movements occur without any effort from the individual, and many of them sustain life and continue if the person is asleep or unconscious. Various signals control these involuntary actions, and the muscles that perform these movements are often smooth in nature, except for the striated cardiac muscle.

Involuntary muscle movement keeps the heart beating.
Involuntary muscle movement keeps the heart beating.

Another function of the muscles in the human body is support. The skeletal muscles are constantly working to support the body and help to maintain posture, whether a person is sitting or standing. The muscles also support, stabilize, and strengthen the joints by holding the bones in proper position, especially in areas where the parts of a joint do not fit together closely, such as the shoulders and hips. The skeletal muscles also are vital in determining overall body strength and the ability to perform various physical tasks. Maintaining strong muscles is helpful for general health and well-being.

The muscles are also important for the maintenance of the correct body temperature. As the muscles consume nutrients to provide power for movement, some of the energy creates heat — it is estimated as much as 75% of the energy produced escapes this way. Considering that skeletal muscle comprises a large percentage of total body mass, the amount of heat generated is significant and plays an important role in maintaining a healthy temperature.

A person's muscles comprises a large percentage of their total body mass.
A person's muscles comprises a large percentage of their total body mass.

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Discussion Comments


Working out and healthy food are very important to improve health and build strong muscles. Go for running, walking, push ups, chair squats, bench presses and push ups to make strong muscles and reduce joints pains. Eat fresh fruits, vegetables and salads. Drink fruit juice and plenty of water. This is really good for health and prevents many diseases.


I have always struggled with poor posture. Even when I was a girl, my mom would tell me to sit up straight and keep my shoulders back. I think years of training my muscles this way have resulted in my poor posture as an adult.

I am making an effort to work on building my back, shoulder and skeletal muscles to help with this. I also take a calcium supplement to strengthen my bones, which should have a positive impact on my muscles too.

When my muscles are toned, I know I feel stronger and more confident. It takes persistent effort for me, but the benefits of keeping my muscles in shape are worth it.


My husband has worked construction for many years and is very muscular. This must be one reason his body puts off so much heat. Sitting next to him feels like you are right next to a furnace.

When it is cold, this isn't so bad, but on hot summer days, it can almost be too much heat. I have a small stature so that probably helps explain why I am cold all the time. Since my body doesn't have as much muscle, it doesn't generate as much heat.

I think the muscles of the human body do much more than we ever realize. When you think about all of the involuntary muscles that keep our bodies going day and night, it really is amazing.


@LisaLou - If I remember right there are around 600 different muscles in your body. I don't know how many of those are voluntary or involuntary. I know that most fitness instructors will say how important it is to include muscle building when you are working out.

I used to just concentrate on getting a good cardio workout, but have come to realize how important it is to strengthen my muscles too. Muscle also burns a lot of energy, so you continue to burn off fat even when your workout is over.

It doesn't seem to take long for muscles to get out of shape if you don't use them continually though. If I get lazy and start skipping the weight machine, I can really tell a big difference when I start back in again. I have to start out slowly and work my way up or I will be so sore that I can hardly walk or move without being in pain.

Does anybody know how many muscles are in the human body? When you stop to think about all of the voluntary and involuntary muscles we have, I imagine there are a lot of them.

The only time I think much about my muscles is when I over work them. When I have sore muscles after doing some workout routine I am not used to, I am aware that I have muscles I didn't even realize I had.

One thing I have noticed is that they seem to recover from something like this within a couple of days. It is good knowing that I have exercised my muscles, but sometimes they are so sore that it is hard to walk up and down stairs.

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