Why Do I Have Stiff Joints After Sitting? (And What To Do About It)

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Imagine this scenario in which you are toiling away at your desk for multiple hours, only to realize it’s well past lunchtime and you haven’t gotten up and walked around since you got to work.

As you finish sending the email you are working on, you push your chair away from your desk and stand up, only to find that you’re stiff after sitting or that you have knee stiffness after sitting.

Experiencing a stiff knee after sitting or stiff legs after sitting is quite common, leading to common questions such as Why do I get so stiff after sitting for a while or Why do I get stiff legs after sitting?

In this article, we will discuss common causes for stiff joints after sitting or stiff legs after prolonged sitting and what to do to prevent feeling stiff after sitting for a while.

We will cover the following: 

  • Why Am I So Stiff After Sitting for a While?
  • How to Prevent Stiff Joints After Sitting

Let’s jump in!

A person holding his stiff joints after sitting.

Why Am I So Stiff After Sitting for a While?

The first thing to establish is that although it’s not necessarily normal to experience stiff legs after sitting or a stiff knee after sitting, questions like “Why do I get stiff after sitting?” or “Why do I have joint stiffness after prolonged sitting?” are extremely common.

Feeling joint stiffness after sitting or stiffness in your legs after sitting for a while is especially common in middle-aged and older adults, though it can also happen in young adults and potentially even adolescents.

Having stiff legs after sitting is generally attributable to either muscle stiffness after sitting or joint stiffness after sitting.

In terms of stiff muscles or tight muscles after sitting, the most common muscle tightness from sitting that people experience is tightness in the hip flexors and quadriceps in the front of the leg and/or muscle tightness in the glutes, hamstrings, and calves in the back of the leg.

Although it’s possible to experience stiff joints after sitting in any of the major joints in the body, it’s particularly common to experience stiff knees after sitting, stiff hips after sitting, or stiff ankles after sitting.

So, what causes stiff joints after sitting and stiff or tight leg muscles after sitting?

The short answer is that joint stiffness, muscle tightness, and stiff tendons after sitting is usually caused by a lack of movement for an extended period of time. 

But why does physical inactivity, either sitting or lying down for a while, cause the body to feel stiff? 

A person holding their knee.

Here are some of the consequences of sitting for a while that can cause stiffness in your legs:

#1: Lack of Circulation

Sitting can reduce circulation to your muscles and connective tissues and will reduce the circulation of the synovial fluid, the lubricating “oil“ in your joints.

Physical activity or moving your body increases circulation to the muscles and joints in your legs.

Blood is warm and carries oxygen and nutrients to these tissues, helping you feel more limber and spry and bathing the muscle fibers in a bounty of rich nutrients.

Consider, for example, the purpose of doing a warm-up before exercise.

Your muscles do receive blood flow at rest, but not nearly as much as when you are up and moving, and certainly less than when you are engaging in vigorous physical activity

This can cause your muscles to feel relatively cold and stiff, which is why some light cardio and dynamic stretching are advisable before jumping into intense exercise after you have been sitting or resting.

A person working at their desk.

Moving your body will enhance circulation to help warm up your muscles and joints and start stretching the muscle fibers and tendon junctions to increase your range of motion and mobility.

As mentioned, the joints are also lubricated with a biological substance known as synovial fluid, which is an oil-like substance inside the joint capsule. The synovial fluid helps reduce friction in your joints so that the bones slide and glide smoothly between one another.

Synovial fluid, like blood, will pool or stop circulating if you sit for a long period of time.

For this reason, you may find that you have a stiff knee after sitting for a while but that the knee stiffness after sitting starts to go away once you get up and start walking or bending your knees. 

Even a couple of partial and then full body weight squats can help start stimulating the flow of synovial fluid within the knee joint capsule, which will help your knees feel agile and lubricated rather than stiff and creaky.

A person at their desk with a stiff neck.

#2: Hemodynamics

Additionally, one reason that your legs get stiff after sitting for a while is that when you are sitting in a chair, the legs are in a dependent position. This means that your legs are below the level of your heart.

This can contribute to swelling in the feet, ankles, calves, and knees.

The veins, which are the blood vessels that carry oxygen back to the heart after circulating to these distal parts of the body, have built-in valves.

These valves help prevent backflow of your blood so that the blood continues to travel back up to your heart. 

Arteries, which are the blood vessels that carry blood from the heart to your extremities and other areas of the body, have muscular walls. The muscles help squeeze and propel blood along the course of the blood vessel to the destination.

Although the valves do help prevent backflow of blood from pooling in the feet or extremities, if you are sitting for a long time and your feet and legs are in the dependent position down from your heart, the blood has to fight against the force of gravity in order to circulate back up to the heart to be reoxygenated in the lungs through the pulmonary circuit.

This means that the deoxygenated blood in your veins may not completely circulate back up to the heart at the same rate at which oxygenated blood is entering the legs through the arteries.

As a result, you can experience some amount of pooling of blood and resultant swelling in your ankles, feet, and lower legs when you sit for a long period of time.

This swelling can lead to a feeling of stiffness or tightness because excess fluid can impede mobility around the joints and will make muscles feel tight.

A person working at a desk.

#3: No Joint Movement

Another reason that your joints can feel stiff after prolonged sitting is because the inactivity means that your joints and muscles are not moving through their range of motion while you sit.

#4: Poor Posture

Another reason for experiencing stiff joints after sitting or tight and stiff muscles after sitting for a while is poor posture and muscle imbalances.

Lower crossed syndrome describes a static and dynamic postural deviation that occurs due to muscle imbalances that develop around the pelvis and hips due to chronic and frequent periods of sitting.

As a result of sitting, particularly with poor posture of the pelvis and lower back, certain muscles become overactive and tight, whereas others become underactive and overstretched.

A person holding their knee.

#5: Delayed-Onset Muscle Soreness

The aforementioned causes of joint stiffness after sitting for a while are all primarily attributable to inactivity.

However, many highly active people, such as runners, cyclists, and people who frequent the gym to lift weights, find that they feel notable joint stiffness after sitting or stiff legs from sitting.

This tends to occur when you do a long or hard workout in the morning and then sit for the rest of the day. 

Particularly if you skip a cool down or do not refuel well after your workout, your muscles can feel very tight and stiff after sitting later on in the day. 

Glycogen needs to be replenished, your cells need adequate hydration, and you should be getting 20 to 25 g of protein within 30 minutes after your workout. 

It is also important to cool down after a vigorous workout rather than quickly shower and then sit at your desk all day. 

Metabolic byproducts accumulate in your legs during long or vigorous workouts, which can contribute to inflammation, stiffness, and soreness after exercise. 

When you sit for a long time after exercising, your muscles are unable to get enough oxygen and nutrients to repair the damage from your workout. Additionally, the circulation to flush away these acidic metabolic byproducts is inadequate.

Doctors walking around at work.

How to Prevent Stiff Joints After Sitting

Here are a few tips to help prevent stiff legs after sitting for a while:

  • Get up at least once an hour and walk around for five minutes or do some jumping jacks, bodyweight squats, marching in place, or take a flight of stairs or two.
  • Stay well hydrated. This will also help you naturally get up once an hour or so to use the bathroom.
  • Cool down and stretch after your workouts, and make sure to focus on proper refueling.
  • Use good posture when you sit with your knees bent 90° and feet flat on the ground. Keep your core tight and your pelvis in a neutral position.
  • Consider physical therapy if you believe you have lower crossed syndrome.
  • Try a standing desk.

For more ideas for improving mobility, check out our guide to the best mobility stretches here.

A person squatting at home.
Photo of author
Amber Sayer is a Fitness, Nutrition, and Wellness Writer and Editor, as well as a NASM-Certified Nutrition Coach and UESCA-certified running, endurance nutrition, and triathlon coach. She holds two Masters Degrees—one in Exercise Science and one in Prosthetics and Orthotics. As a Certified Personal Trainer and running coach for 12 years, Amber enjoys staying active and helping others do so as well. In her free time, she likes running, cycling, cooking, and tackling any type of puzzle.

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