If you have an office worker or desk job, you probably spend 8 to 10 hours sitting all day. You may have noticed that your legs feel heavy, your ankles swell, or your energy drops by late afternoon. You are not alone. Millions of people experience the same thing during their workday sitting.
What you may not know is that a small muscle in your calf — the soleus muscle — plays a major role in leg circulation and energy. Researchers call it the "second heart." When you sit for hours, this muscle becomes largely inactive. That may explain why sitting all day affects your legs and leaves you feeling tired.
Heavy legs, swollen ankles, reduced circulation, and fatigue during prolonged sitting are all examples of what we call Soleus Health — the study of how soleus activity influences health during seated hours. Explore sitting physiology →
This page collects educational resources for office workers and anyone with a desk job about leg health, circulation, energy, and the soleus muscle. This is not medical advice. If you have concerns about your health, consult a doctor.
Educational purpose only. This information is not medical advice. If you have sudden leg swelling, pain, or difficulty breathing, seek medical attention immediately.
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If you have a desk job, you have probably felt it: that mid afternoon energy crash even though you have been sitting all day. You might expect to feel rested after sitting for hours. Instead, you feel drained.
One reason may be circulation. When you sit all day, the soleus muscle in your calf becomes less active. This muscle normally helps pump blood upward from your legs. When it slows, blood can pool in your lower legs. Your body has to work harder to maintain circulation, which may contribute to feelings of fatigue.
Another reason is reduced muscle activity throughout your body. Sitting all day means large muscle groups are not contracting the way they would during standing or walking. This can affect how your body manages energy. The result is that after a full workday sitting, you feel paradoxically more tired than if you had been moving.
Learn more about leg heaviness after sitting →
Explore these guides to learn more about what sitting all day does to your legs, circulation, and energy.
Why do my legs feel heavy after sitting all day? The soleus muscle plays a key role in leg circulation.
Read the full guide →Why do my ankles swell after a long workday? Learn how the calf muscle pump affects fluid movement.
Read more →Everything you need to know about the soleus muscle, including anatomy, function, and how it affects circulation during sitting all day.
Read the guide →A new wellness category focused on understanding and activating the soleus muscle during seated hours.
Learn more →A seated heel-raise movement that activates the soleus muscle. Learn how to do it and why researchers studied it.
Read more →The study of what happens inside the body during prolonged seated time. A missing piece of modern health.
Read more →Learn why researchers call the soleus muscle your body's "second heart" and how it supports circulation.
Read more →Published research on the soleus muscle, circulation, and metabolic health.
View research →The Houghton 2021 study found that people with reduced calf muscle pump function were twice as likely to experience serious health events over time. The Niccolini 2020 study confirmed that during soleus contraction, upward blood flow increases 4x compared to rest. These studies help explain why sitting all day may affect leg health and circulation.
These studies are independent. 2HEART did not conduct them. We cite them because they explore the same problem we are working on: what happens to the body during prolonged sitting.
If you have sudden swelling in one leg only, accompanied by pain, redness, or warmth, seek medical attention immediately. These could be signs of a blood clot (DVT).
If you have swelling accompanied by chest pain or difficulty breathing, call emergency services immediately.