Exercising This Forgotten Muscle Can Boost Your Metabolism
There was something strange about the rabbits...
It was 1873, and French scientist Louis Ranvier was studying the muscles of rabbits. That's when he noticed something odd... Some of the rabbits' muscles were darker and redder – and they behaved differently from the others.
While the paler muscles contracted quickly and powerfully, the redder ones contracted more slowly... But they could keep working longer without tiring out.
Humans have these redder muscle fibers too. Today, we know them as type 1, or "slow twitch," fibers. They're rich in blood vessels and other features that optimize oxygen use and energy production over long periods of time.
Turns out, these muscle fibers appear in a small muscle that research shows could help boost your metabolism – and keeping it active is a lot easier than you might think...
It's called the soleus. And it's one of the major muscles that make up your calf. The soleus sits underneath the larger, more visible gastrocnemius muscle and stretches around your Achilles tendon toward the back of your knee. And even though it accounts for just 1.3% of your total body weight, it's a total powerhouse. Take a look...
The soleus is packed with those slow-twitch fibers I mentioned... the ones built for the long haul. These fibers can keep contracting for long periods of time without tiring. And boy, does that come in handy since the soleus muscles work hard in the background all day...
They help you stand upright, walk, maintain your balance, pump blood from your legs back to your heart, and more.
What sets the soleus apart from the other muscles in your body is that under certain conditions, it can keep working without quickly burning through its storage reserves of glucose (i.e., glycogen).
Instead, the soleus can draw more of its fuel – glucose and fats – straight from the bloodstream. Researchers think the soleus's slow-twitch fibers, rich blood supply, and other unique metabolic features all help make this feat possible.
That's why more research is showing that keeping this small muscle active can have a surprisingly big effect on your metabolism...
For instance, a 2022 study found that exercising the soleus with one simple seated movement can increase the body's rate of burning glucose to as much as 300% of its resting level. And that's despite the muscle making up just 1.3% of body mass.
How to Exercise Your 'Metabolic Workhorse'
We first introduced this movement to Health & Wealth Bulletin readers in a 2022 issue. It's called the "soleus pushup," and it was developed by researchers at the University of Houston.
As a quick refresher, this isn't the kind of pushup that has you lying flat on the floor. Instead, you perform it sitting in a chair.
In the University of Houston's 2022 study that introduced this movement, 25 participants sat while repeatedly raising and lowering their heels in a specific way to keep the soleus working for long periods – all measured by specialized equipment.
In one part of the study, 10 of the participants first sat still for four and a half hours. After that, they performed the soleus pushups for the same amount of time. Muscle samples then confirmed that the soleus used very little glycogen to perform the movement. Instead, it relied more heavily on pulling its fuel from the bloodstream... Just by performing this movement, participants roughly doubled their glucose and fat metabolism.
In the second segment of the study, researchers gave the other 15 participants a sugary drink before they performed soleus pushups for three hours. Compared with sitting still, doing the movement improved their post-meal glucose response by 52%, and their insulin response fell by 60%.
Another interesting study, from 2025, had similar findings... It involved 10 adults who had been diagnosed with prediabetes. First, participants tested their baseline glucose levels by drinking a sugary solution and then sitting for two hours while researchers monitored their blood sugar.
Then, on a separate occasion, they repeated the glucose test while performing soleus pushups. This time, half of the participants received real-time feedback from equipment showing them how well they were activating their soleus. The others performed the movements without the high-tech stuff.
Overall, performing the pushups reduced participants' rise in blood sugar by roughly 32% compared with sitting still.
And get this: Even participants who didn't use the fancy equipment benefited from this movement.
In other words, you don't have to be in a laboratory setting to reap the benefits from putting your soleus to work.
Now, keep in mind... This was a super-small pilot study with just 10 folks, and the researchers themselves confirmed larger studies are needed. So I'm not saying doing this movement will magically cure your high-blood-sugar woes... or that you should ditch walking and regular exercise completely.
Instead, think of these pushups as a way to make some of your sitting time a little less sedentary.
Here's how to get started...
- Sit in a chair with your knees hip-width apart. Relax your leg muscles and make sure both feet are flat on the floor.
- Next, raise both heels while keeping the front halves of your feet firmly planted on the floor.
- When your heels are as high as they can go, let them drop back to the floor.
- Repeat this motion while you sit comfortably. You can also click here to see an example of the movement from the University of Houston's study.
So whether you're stuck behind your desk... catching up on your favorite Netflix series... sitting through a long meeting... or taking a long flight... you can put your calves to work – and boost your metabolism in the process.
And exercising your soleus muscle isn't the only small change that can make a big impact on your health...
Unfortunately, when medications add up over the years, they can have a negative impact. And with nearly half of America's seniors taking at least five different prescriptions at once, "polypharmacy" is sneaking up on a lot of folks as they age – and it can lead to a host of harmful side effects. In my latest issue of Retirement Millionaire, I explained all the details, including how you can give your own medication regimen a "reset." (If you're not a subscriber, you can get a monthlong trial here.)
What We're Reading...
- Something different: The secret to cleaning dirty hands.
Here's to our health, wealth, and a great retirement,
Dr. David Eifrig and the Health & Wealth Bulletin Research Team
August 25, 2026