YOUR SECOND HEART
The Muscle Most People Never Think About
A Small Muscle. A Surprisingly Important Role in Your Health.
An Educational Health and Knowledge Sharing Article
By Dr. Amarjeet Singh @ AJ
We spend thousands of ringgit on smart watches, supplements, gym memberships, health screenings and wellness programmes.
Yet many of us overlook one of the body’s simplest and most remarkable natural mechanisms—a powerful muscle hidden deep inside the calf.
Most people know that the heart pumps blood throughout the body. But there is another important pumping mechanism in our lower legs that helps blood return towards the heart.
It involves the calf muscles—particularly the soleus muscle.
WHAT IS THE SOLEUS MUSCLE?
The soleus is a broad, powerful muscle located underneath the larger and more visible calf muscle known as the gastrocnemius.
It begins below the knee and connects to the heel through the Achilles tendon. Together with the gastrocnemius, it helps us:
- Stand upright
- Walk and climb stairs
- Push the foot downward
- Raise the heel
- Maintain posture and balance
Unlike muscles primarily associated with explosive speed and power, the soleus contains a large proportion of slow-twitch muscle fibres.
These fibres are relatively resistant to fatigue and are suited to long periods of low-level activity, such as standing and walking.
WHY IS IT SOMETIMES CALLED A “SECOND HEART”?
The phrase “second heart” is a popular description rather than a statement that the soleus literally functions like the heart.
The actual heart remains the body’s central pump. However, the calf muscles form an important peripheral muscle pump that supports the return of venous blood from the lower legs.
When the calf muscles contract during walking, ankle movement or heel raising, they compress veins running through and around the muscle tissue.
One-way valves within healthy veins help direct the blood upwards and reduce backward flow.
Every step activates a natural pumping mechanism that helps move blood out of the lower legs and back towards the heart.
When people remain still for long periods, this muscle-pump activity decreases. Blood may remain in the lower limbs for longer, contributing to sensations such as heaviness or swelling in susceptible individuals.
Circulation, however, depends on several interacting systems. It would be inaccurate to suggest that the soleus works alone or that activating one muscle can prevent every circulation-related condition.
MODERN LIFE HAS CREATED A MOVEMENT PROBLEM
Human beings were designed to move regularly.
But modern life encourages us to remain seated:
- We sit while driving.
- We sit through long meetings.
- We sit at our desks.
- We sit during flights.
- We sit while eating.
- We sit while watching television.
- We sit while scrolling through our phones.
The issue is not simply that we sit. The greater concern is that many people remain almost completely inactive for hours without meaningful movement.
The human body was designed for movement—not prolonged stillness.
THE SCIENCE IS BECOMING MORE INTERESTING
In 2022, researchers led by Professor Marc Hamilton published a study examining a specialised seated movement known as the soleus push-up, or SPU.
During the movement, the person remains seated with the front of the foot on the floor. The heel is raised while the toes and forefoot remain in contact with the ground, before the heel is lowered again.
The researchers reported that this particular form of soleus-dominant activity could substantially increase local oxidative metabolism for extended periods, with relatively little fatigue.
The study also reported improvements in aspects of post-meal glucose and lipid regulation under controlled research conditions.
Important: These findings are scientifically interesting, but they should not be interpreted as proof that ordinary heel raises will automatically produce identical results in everyone.
The movement studied by the researchers involved a specific technique and controlled conditions. More independent research across different populations is needed to determine its wider long-term clinical value.
IT IS NOT A MIRACLE EXERCISE
Social media has a habit of turning promising research into dramatic headlines.
Some posts suggest that activating the soleus can replace walking, gym training, prescribed medication or established diabetes management.
That is an irresponsible exaggeration.
A seated calf movement does not provide all the cardiovascular, muscular, skeletal, psychological and functional benefits associated with regular physical activity.
It should not be treated as a replacement for:
- Regular walking
- Cardiovascular exercise
- Strength and resistance training
- Balanced nutrition
- Adequate sleep
- Weight management where medically appropriate
- Medical treatment prescribed by qualified professionals
Never stop or alter diabetes, blood-pressure, heart or blood-thinning medication because of an exercise claim found online.
A SIMPLE MOVEMENT WHILE SEATED
A basic seated heel raise can be used as a movement break during prolonged sitting:
Step 1: Sit upright with both feet resting on the floor.
Step 2: Keep the front portion of the foot and toes in contact with the floor.
Step 3: Lift the heels comfortably.
Step 4: Lower the heels in a controlled manner.
Step 5: Repeat gently without forcing the ankle or calf.
This is a general mobility suggestion, not a guarantee that a person is reproducing the precise laboratory soleus push-up technique.
Stop if the movement causes pain, cramping, dizziness, unusual breathlessness or worsening discomfort.
WHO SHOULD PAY ATTENTION?
Regular lower-leg movement may be especially relevant to:
- Office workers who sit for long periods
- Drivers travelling long distances
- Frequent airline passengers
- Older adults with reduced mobility
- People working from home
- Individuals who spend hours in meetings
- Anyone trying to reduce prolonged sedentary time
People with diabetes, heart disease, circulation disorders, previous blood clots, severe varicose veins, recent surgery, injuries or significant leg swelling should seek personalised medical advice before beginning a new exercise programme.
DO NOT ASSUME EVERY CALF PROBLEM IS “JUST POOR CIRCULATION”
Calf pain and swelling can have many causes, ranging from muscle strain to conditions requiring urgent assessment.
Seek prompt medical attention for unexplained swelling—especially when it affects only one leg—or when calf pain is accompanied by warmth, redness, chest pain, faintness or shortness of breath.
Do not massage or repeatedly exercise a painful, suddenly swollen leg without first obtaining appropriate medical advice.
SMALL MOVEMENTS CAN BECOME POWERFUL HABITS
You do not necessarily need sophisticated equipment to reduce long periods of inactivity.
Consider building simple movement into your day:
- Stand and move regularly.
- Walk whenever practical.
- Use stairs when physically suitable.
- Move your ankles during long periods of sitting.
- Take brief walking breaks between meetings.
- Perform comfortable heel raises while waiting.
- Avoid allowing an entire day to pass without purposeful movement.
Health is not created only during one hour at the gym.
It is also shaped by what we do during the remaining hours of the day.
THE BIGGER LESSON
The story of the soleus muscle carries a lesson that extends beyond anatomy.
We often search for dramatic solutions while ignoring the power of small, consistent actions.
A short walk may appear insignificant.
A few minutes of movement may appear unimportant.
Standing after a long meeting may appear too simple to matter.
Yet health is rarely transformed by one spectacular decision.
It is built through hundreds of small decisions repeated consistently.
The soleus reminds us that some of the body’s most valuable work occurs quietly, continuously and without recognition.
The smallest structures can carry major responsibilities.
The smallest habits can create meaningful change.
And the smallest movement is still better than complete inactivity.
FINAL THOUGHT
We spend much of our lives searching for the next miracle supplement, revolutionary machine or instant health solution.
But sometimes the most practical answer is already part of us.
Stand up.
Walk more.
Move regularly.
Activate the body you were given.
Your body was built to move.
The question is—are you giving it the opportunity?
Knowledge Creates Awareness.
Awareness Encourages Action.
Consistent Action Builds Better Health.
Dr. Amarjeet Singh @ AJ
Business Consultant • Strategist • Writer • Health Awareness Advocate
1. Hamilton, M.T., Hamilton, D.G. and Zderic, T.W. “A Potent Physiological Method to Magnify and Sustain Soleus Oxidative Metabolism Improves Glucose and Lipid Regulation.” iScience, 2022.
2. Medical literature on calf-muscle-pump function, venous return and chronic venous disease.
3. Anatomical research examining the venous-muscular pumps of the lower limbs.
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