Why Does Sitting at a Computer Cause Knee Pain?

Back in 2011, I didn’t realize my knee pain was caused by sitting at a computer for long periods of time. I thought it was from overtraining. Besides, the first time I ever felt knee pain was after a long run. But the pain that day was the effect of my problem. Running was a variable that made the knee pain worse. However, the cause of the knee pain was repetitive strain from sitting at a computer for long periods of time.

Photo by Khosrork via Megapixl

Why does sitting at a computer cause knee pain?

As soon as I felt knee pain, I made an appointment with a massage therapist. He was a really sharp guy. He was also a CrossFit coach, which is the main training method I was doing back then.

I told him my knees hurt, but I wasn’t sure why. He explained to me that pain and inflammation in a joint is often caused by a tight muscle somewhere else. Muscles are attached to tendons. Tendons are attached to bones. Often at a joint, like a knee.

For example: the quadriceps, hamstrings, IT bands, and calves all attach to tendons at the knee. When these muscles get tight, we might feel muscle tension. But it didn’t really hurt in the muscle for me. It just felt tight. The problem is, tight muscles pull extra hard on tendons, which get overextended easily. These tendons at the knee are where we’re more likely to feel the pain first.

None of my content is professional medical advice. I write about my personal experience. What worked for me. And what didn’t. I write about the poor posture mistakes I made at a computer. Then, I write about how I fixed those mistakes into correct posture. Do your research. Make good decisions. And be the best advocate possible for your own healthcare.

Photo by Pixologic via Megapixl

Tight hamstring muscles

There are 3 hamstring muscles on each leg. All 3 of them attach to a tendon at the knee. When one (or more) of them is tight, it can overextend it’s tendon(s). This caused long term knee pain and inflammation for me.

illustration of having a tight hamstring - sitting at a computer cause knee pain
Photo by MedicalStocks via Megapixl

The above picture shows the 3 hamstring muscles in the leg. If you look closely at the knee joint, you can see the light-colored tendons that attach to bones.

But, I know. That still doesn’t explain how they get tight from sitting. Take a look at the picture below.

Photo by Inegvin via Megapixl

The user on the left has poor posture. His hamstrings are constantly activated and overused. I know this because his feet are pulled underneath his office chair. In order to pull his feet back under him, he has to contract his hamstring muscles. He also has his knees bent too much. This will overextend his quadriceps. Holding his quadriceps like this for long periods will overuse and lengthen them. These are all classic poor posture mistakes I used to make.

The user on the right is using correct posture for sitting at a computer. He has his knees bent at a comfortable angle. He has his feet flat on the floor and not pulled back underneath him. That’s how we know the hamstrings are in a balanced, neutral position.

If you like this article, click here to check out my book titled, "45 Ways to Improve Computer Posture."

Tight calf muscles

illustration of a person sitting with tight calf - sitting at a computer cause knee pain
Photo by Eraxion via Megapixl

Notice how this user has one foot flat on the floor in correct posture. But his other foot is pulled underneath his office chair, resting on his toes. This poor posture mistake overextends the calf muscle. I used to sit in this position for long periods. It essentially lengthened the calf muscles, making them weaker and less activated. Just like the hamstrings, the calves are connected to tendons that attach to bone in the knees. I never felt pain in my overextended, overused calves. It was always in my knees.

Tight psoas muscles

The psoas is a very complex group of muscles. They all attach, via tendons, to different bones (lumbar spine, pelvis, and thigh bone). I try not to get too tied up in high-level anatomy of the body. Because that can get pretty intense. But take a quick glance at the picture below to get a basic understanding of the psoas muscles.

tight psoas muscle illustration - sitting at a computer cause knee pain
Photo by Maubuk77 via Megapixl

On the other hand, what I try to do when it comes to anatomy, is to correct posture mistakes as simply as possible. In my experience, my psoas muscles got super tight from one main reason. My torso would slouch forward at an excessive angle. The psoas muscles are working overtime in this poor posture position. Take a look at the picture below for a good example of a user slouching forward.

person leaning towards the monitor
Photo by AndreyPopov via Megapixl

Everything in the Body is Connected

It may not seem likely that a tight psoas would cause me to suffer from knee pain. Maybe not directly, because the psoas doesn’t attach to the knee. However, everything in the body is connected. And the psoas connects to the thigh bone, which supports both the quadriceps and the hamstrings. With that said, my tight psoas indirectly caused me to suffer from knee pain. It made all the muscles in my upper legs work harder than necessary to compensate for my tight psoas muscles.

difference between sitting properly and not
Photo by Burlesck via Megapixl

Take a look at the user on the left in the above picture. This is how I used to sit. My office chair and hips were too low. I had my knees bent too much. But most importantly, look at how his torso is slouched forward. Look at the large difference in the angle of the hips, compared to the user on the right who has correct posture.

How to avoid knee pain caused by sitting at a computer

Keep your feet flat on the floor, or a footrest, at all times.

When working at a computer for long periods, keeping my feet flat on the floor is a good posture habit that has helped me avoid knee pain. This keeps the hamstring muscles in a neutral position. It also keeps the knees bent comfortably, which decreases muscle tension in the quadriceps. Notice the picture below for a good example on how to sit properly in an office chair.

Photo by Eraxion via Megapixl

Side note: You may have noticed that I said keep your feet flat on the floor “or a footrest.” If your desk is not height adjustable, you may need to raise your chair height to get your elbow level above your desk. After elbow level is correct, your feet may or may not be able to touch the ground. If they don’t touch, this is when a footrest is necessary. Elbow level, desk chair level, and desk level can very depending on the user. Click here to download my free ebook that explains these variables.

Maintain a neutral spine when using a computer.

Mainly, don’t slouch forward. This will avoid overusing tight psoas muscles. But also, don’t sit up “too straight.” This can overextend the lumbar spine. The spine isn’t a straight line. It has natural curves in it. In order to be in a balanced, neutral position, the spine needs to maintain its natural curves.

Photo by Logo3in1 via Megapixl

Check out the above photo for another example of slouching forward with poor posture (on the left). The user on the right has a neutral spine with correct posture. To learn more about how to maintain a neutral spine, click here to check out my article titled, “Can Sitting at a Computer Cause Back Pain?”

Switch from sit to stand positions multiple times throughout the day.

One way to avoid knee pain is to stop sitting for long periods of time. I can get the same amount of work done, if not more, when I switch from sit to stand positions multiple times throughout the day. Having a desk that is height adjustable makes this transition very easy.

This user shows an example of correct posture while standing at her height adjustable computer desk. Standing posture at a computer is a great way for me to naturally lengthen the psoas and hamstring muscles. Muscle tension in these 2 muscle groups were a big contributor to my knee pain caused by sitting at a computer.

Notice how she has one of her knees bent. This is an acceptable position, as long as she doesn’t stand with the same knee bent for long periods. It’s important to switch up. Keep the right knee bent for a while. Then, left knee bent for a while.

Standing on a hard floor for long periods also caused me to suffer from knee pain. I was able to relieve this problem and avoid knee pain by using an anti-fatigue mat when standing. I got mine for $14 on Amazon (not paid promotion).

Thanks for your interest in computer posture. 

If you haven’t already, download my free ebook titled 3 Ways to Improve Computer Posture Immediately!   

>>> Click here to download your ebook

Ways to Improve Computer Posture

This ebook talks about the 3 most painful computer posture mistakes I used to make. Then, it talks about how I fixed those mistakes with 3 simple changes to my ergonomic computer workstation. 

Take care,

Todd Bowen

P.S. You can sign up for my free computer posture newsletter here.

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