• Porch House Clinic

Our Second Heart

Updated: Jan 27

Most of us are aware of the phenomenal job our heart is doing, pumping blood out to our extremities all day every day. But are you aware of the amazing job our deep muscles are doing to pump that blood back towards the heart? One of the most important of these is the soleus muscle of the lower leg and that is exactly why it is sometimes referred to as our 'second heart.'

Where is the soleus muscle and what makes it so important?

The soleus muscle extends from the ankle to the back of the knee, lying predominantly behind the two-headed gastrocnemius muscle that we clearly see at the back of the lower leg. In conjunction with the plantaris muscle, the soleus and gastrocnemius form the 'triceps surae,' or what we commonly refer to as the calf muscle. Both the gastrocnemius and the soleus fuse together and attach to the strong calcaneal tendon (or Achilles tendon).

Soleus Muscle

Gastrocnemius Muscle

The positioning of the soleus muscle, far away from the heart and towards the lowest gravitational point when standing, places it in an ideal position to work together with the heart as a super-efficient pumping system. The heart exerts enough power in just one pump to send oxygen and nutrient-rich blood throughout the body and to the lower extremities within seconds. However, getting blood back to the heart and lungs to replenish those supplies (and in the process to eliminate toxins through the lungs, kidneys and liver along the way) is another matter altogether. As this process is now running against gravity, it requires significant help from veno-muscular pumps to keep blood flowing back to the heart efficiently and in the right direction.

How does the soleus muscle work as a pump?

The process of venous return starts with the foot. As you take a step, the heel touches down and blood collects in the veins. As the front of the foot connects with the ground, this blood is pushed upwards towards the soleus muscle. Then, as the soleus muscle contracts, it exerts another upward pressure which propels the blood onwards, up through its veins to the knee and on towards the groin. It then continues with less support from the lower leg through the abdominal cavity and up through the vena cava to the heart. The stronger and healthier the ankle and the soleus muscle, the stronger this important partnership.

What happens if you don't use your calf muscle?

When you stop moving, the heart continues to apply some direct pressure BUT the rate of blood flow throughout the lower leg slows significantly as that upward pressure stops. As time goes on, blood pools in the veins and puts us at greater risk of developing spider veins, varicose veins and even blood clots.

What's more, if your lifestyle is highly sedentary or you spend long periods standing still on your feet, the one-way valves in those deep leg veins can become weak and inefficient. Blood falls backwards and pools in the lower legs which can lead to swelling, pain, cramp, ulcers and even a deep vein thrombosis (DVT) that can potentially travel upwards and be extremely serious. The risk further increases if you are overweight.

A largely sedentary lifestyle, ageing and injury can all contribute to muscle atrophy too, or muscle wasting, and the smaller our soleus muscle becomes, the harder it has to work to get the job done. This can lead to exhaustion caused by over-exertion when exercising and also leaves you at greater risk of heart disease.

How do you maintain a strong and efficient calf muscle pump?

It really does come down to exercise and nutrition, it's that simple! Continue to keep your soleus well-nourished, strong and injury-free and you can proactively assist your heart in circulating your blood, moving deoxygenated blood and toxins up and away from your lower extremities and this in turn will have a powerful impact on your overall health.

At Porch House clinic, we have a deep understanding of muscles, tendons, ligaments, nerves and joints and we are seriously proactive in our approach to any musculoskeletal pain or injury. We have high expectations ourselves so we deliver those for you too. If you need help with a lower limb injury, or any musculoskeletal pain or injury, we use the most effective hands-on techniques to accelerate your recovery and we expect some pretty serious results.

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