Circulatory system 101

The job of circulating blood round your body is owned by your actual heart (obvs) plus your arteries. The arteries are the blood vessels carrying blood from the heart to the rest of your body. They're highly elastic to manage the pressure of blood being pushed out from the heart.

This is what's being measured when you measure your blood pressure. 

The arteries get smaller and smaller so that they can bring oxygen and nutrients to all the cells in your body.

After dropping off the oxygen and nutrients, the blood picks up waste products and carbon dioxide and is carried back to the heart by your veins.

Whereas, veins have zero pressure. The "push" from the heartbeat has long been spent. So they rely on the contraction of the muscles around them to push blood back to your heart.

How does blood get from your feet back up to your heart?

Imagine all the blood that's been pumped down at pressure (and for the most part with the assistance of gravity) to your feet. Now, it has to get back to your heart. Against gravity. And with no pressure. This is where your calf muscles come in. When they contract, they squeeze the veins and push the blood back up towards our heart.

They're helped by valves in the veins that stop the blood from going backwards.

Without this pumping action, blood would pool in our legs, which would leading to swelling, varicose veins, and poor circulation. This is why if you've ever been doing something that really lifts your heart rate, and then suddenly stop or sit down, you can feel a bit wobbly -because the blood's not being moved by the calf muscles back to the heart.

What's the "basic" job of your calf muscles?

So, we've identified this extra job of pushing blood back up the body, but from a purely musculoskeletal (JMSK) point of view, and has two jobs - to provide "push off" action for walking, running and jumping (see also my blog about your big toe here); and to stabilise.

As you might imagine, with two jobs, there are two muscles. Your gastrocnemius, which is the bigger of the two (and the one you can see when you look down at your leg); and the soleus.

The gastroc is full of fast twitch muscles for explosive action and is responsible for driving movement. It works best when the knee is straightened and lifts the heel off the floor and points the toe downwards

But your soleus is all about the slow twitch for endurance and looks after stability of the ankle and knee joints and works best when your knee's bent.

The surprising truth about your soleus and metabolic health

Your gastroc muscle wants a quick easy energy source and takes glycogen out of your blood. This store quickly depletes (which is fine, because we're looking for explosive power).

But the soleus muscles are a special collection of slow twitch muscles, and like to do things a bit differently. They take the glucose and fat that's being carried in the blood and use that directly. And they carry on doing it because - endurance!

Why does this matter particularly as we transition through menopause? 

Because as we transition, our bodies become less efficient at managing glucose. Insulin resistance increases (=> pre-diabetes/diabetes) , muscle mass decreases (=> sarcopenia), and our ability to switch between burning sugar and fat reduces.

How to activate your calf muscles for heart, metabolic & functional health

Well, this is interesting. A 2022 study identified that doing a small exercise called a "Soleus Push Up" can substantially improve metabolic health, heart health and general function.

The exercise is super simple. Sit upright on a stationary chair with your feet on the floor and your ankles under your knee. Push your right ankle joint, where your foot and leg meet forward, slowly rolling through the foot to lift the heel. The roll it back down. Repeat at a rate of 1/ second for about a minute, before swapping legs.

As you get used to it, try and speed it up and, if you like both legs at the same time.

You can do this anytime you're sitting still. But an especially great time to would be after you've eaten to help your body to process the glucose you've just taken on board.

There's also a link to a video for the exercise at the bottom of this email.

The benefits of the Soleus Push Up.

Circulatory Benefits:

• Prevents blood pooling in lower legs.
• Reduces risk of varicose veins and swelling.
• Supports cardiovascular health.
• Improves overall energy and reduces leg fatigue.

Metabolic Benefits:

• Improves glucose uptake from the bloodstream.
• Reduces post-meal blood sugar spikes.
• Enhances insulin sensitivity.
• Supports healthy weight management.

Functional Benefits:

• Strengthens the muscles needed for walking and balance.
• Reduces fall risk (strong calves = better ankle stability).
• Prevents age-related muscle loss in the lower legs.

If you're interested in more calf muscle work, please shout. Of course, I have some other exercises you can do!



Read more:

The 2022 Study

Video for soleus push ups by the lead author of the paper