‘Special’ Muscle Can Promote Glucose and Fat Burning to Fuel Metabolism for Hours While Sitting

Summary: The pioneering “soleus pushup” effectively elevates muscle metabolism for hours, even when sitting.

Source: University of Houston

From the same mind whose research propelled the notion that “sitting too much is not the same as exercising too little,” comes a groundbreaking discovery set to turn a sedentary lifestyle on its ear: The soleus muscle in the calf, though only 1% of your body weight, can do big things to improve the metabolic health in the rest of your body if activated correctly.  

And Marc Hamilton, professor of Health and Human Performance at the University of Houston, has discovered such an approach for optimal activation – he’s pioneering the “soleus pushup” (SPU) which effectively elevates muscle metabolism for hours, even while sitting. The soleus, one of 600 muscles in the human body, is a posterior leg muscle that runs from just below the knee to the heel. 

Published in the journal iScience, Hamilton’s research suggests the soleus pushup’s ability to sustain an elevated oxidative metabolism to improve the regulation of blood glucose is more effective than any popular methods currently touted as a solution including exercise, weight loss and intermittent fasting. Oxidative metabolism is the process by which oxygen is used to burn metabolites like blood glucose or fats, but it depends, in part, on the immediate energy needs of the muscle when it’s working. 

“We never dreamed that this muscle has this type of capacity. It’s been inside our bodies all along, but no one ever investigated how to use it to optimize our health, until now,” said Hamilton. “When activated correctly, the soleus muscle can raise local oxidative metabolism to high levels for hours, not just minutes, and does so by using a different fuel mixture.”  

Muscle biopsies revealed there was minimal glycogen contribution to fueling the soleus. Instead of breaking down glycogen, the soleus can use other types of fuels such as blood glucose and fats. Glycogen is normally the predominant type of carbohydrate that fuels muscular exercise.  

“The soleus’ lower-than-normal reliance on glycogen helps it work for hours effortlessly without fatiguing during this type of muscle activity, because there is a definite limit to muscular endurance caused by glycogen depletion,” he added. “As far as we know, this is the first concerted effort to develop a specialized type of contractile activity centered around optimizing human metabolic processes.” 

When the SPU was tested, the whole-body effects on blood chemistry included a 52% improvement in the excursion of blood glucose (sugar) and 60% less insulin requirement over three hours after ingesting a glucose drink.  

The new approach of keeping the soleus muscle metabolism humming is also effective at doubling the normal rate of fat metabolism in the fasting period between meals, reducing the levels of fat in the blood (VLDL triglyceride). 

The Soleus Pushup 

Building on years of research, Hamilton and his colleagues developed the soleus pushup, which activates the soleus muscle differently than when standing or walking. The SPU targets the soleus to increase oxygen consumption – more than what’s possible with these other types of soleus activities, while also being resistant to fatigue. 

This shows the researcher and a woman on the breathing apparatus
Marc Hamilton, professor of Health and Human Performance at the University of Houston, is pioneering the “soleus pushup” for the calf muscle that is only 1% of your body weight, but can improve the metabolic health in the rest of your body if activated correctly. Credit: University of Houston

So, how do you perform a soleus pushup?  

In brief, while seated with feet flat on the floor and muscles relaxed, the heel rises while the front of the foot stays put. When the heel gets to the top of its range of motion, the foot is passively released to come back down. The aim is to simultaneously shorten the calf muscle while the soleus is naturally activated by its motor neurons. 

While the SPU movement might look like walking (though it is performed while seated) it is the exact opposite, according to the researchers. When walking, the body is designed to minimize the amount of energy used, because of how the soleus moves. Hamilton’s method flips that upside down and makes the soleus use as much energy as possible for a long duration. 

“The soleus pushup looks simple from the outside, but sometimes what we see with our naked eye isn’t the whole story. It’s a very specific movement that right now requires wearable technology and experience to optimize the health benefits,” said Hamilton.  

Additional publications are in the works focused on how to instruct people to properly learn this singular movement, but without the sophisticated laboratory equipment used in this latest study.  

Credit: University of Houston

The researchers are quick to point out that this is not some new fitness tip or diet of the month. It’s a potent physiological movement that capitalizes on the unique features of the soleus.  

Potential first step toward a health care breakthrough 

Hamilton calls it the “most important study” ever completed at his Metabolic Innovations lab at UH and said the discovery could be a solution to a variety of health problems caused by spending hours each day living with muscle metabolism that is too low, caused by inactivity. The average American sits about 10 hours a day.  

Regardless of a person’s level of physical activity, too much sitting has been shown to increase the risk of heart disease, diabetes, dementia and more. Over half of all American adults, and 80% of people over 65, are living with the metabolic problems caused by either diabetes or prediabetes. 

Having a low metabolic rate while seated is especially troublesome for people who are at high risk for age-associated metabolic diseases such as metabolic syndrome and type 2 diabetes.   

Hamilton said inactive muscles require less energy than most people seem to understand, saying it’s “one of the most fundamental, yet overlooked issues” guiding the way toward discovering metabolic solutions to assist in preventing some age associated chronic diseases. 

“All of the 600 muscles combined normally contribute only about 15% of the whole-body oxidative metabolism in the three hours after ingesting carbohydrate. Despite the fact that the soleus is only 1% the body weight, it is capable of raising its metabolic rate during SPU contractions to easily double, even sometimes triple, the whole-body carbohydrate oxidation.  

 We are unaware of any existing or promising pharmaceuticals that come close to raising and sustaining whole-body oxidative metabolism at this magnitude.” 

About this metabolism research news

Author: Laurie Fickman
Source: University of Houston
Contact: Laurie Fickman – University of Houston
Image: The image is credited to University of Houston

Original Research: Open access.
A potent physiological method to magnify and sustain soleus oxidative metabolism improves glucose and lipid regulation” by Marc Hamilton et al. iScience


A potent physiological method to magnify and sustain soleus oxidative metabolism improves glucose and lipid regulation

Slow oxidative muscle, most notably the soleus, is inherently well equipped with the molecular machinery for regulating blood-borne substrates.

However, the entire human musculature accounts for only ∼15% of the body’s oxidative metabolism of glucose at the resting energy expenditure, despite being the body’s largest lean tissue mass.

We found the human soleus muscle could raise local oxidative metabolism to high levels for hours without fatigue, during a type of soleus-dominant activity while sitting, even in unfit volunteers. Muscle biopsies revealed there was minimal glycogen use.

Magnifying the otherwise negligible local energy expenditure with isolated contractions improved systemic VLDL-triglyceride and glucose homeostasis by a large magnitude, e.g., 52% less postprandial glucose excursion (∼50 mg/dL less between ∼1 and 2 h) with 60% less hyperinsulinemia.

Targeting a small oxidative muscle mass (∼1% body mass) with local contractile activity is a potent method for improving systemic metabolic regulation while prolonging the benefits of oxidative metabolism.

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  1. When the heal reaches the ‘up’ position, should the calf muscle be held tightly for 1-2 seconds before returning down? How many of these should be done daily to get the full affect?

  2. So, does this mean that my ADHD/ADD habit of bouncing one or both of my legs in the ball of my foot when sitting can contribute to weight loss?

  3. Soleus is a soft muscle, one of the four muscles types is like the biceps brachii (bipennate), and may not atrophy if not activated for a number of weeks. Could it be like a second “heart”? The four types are muscle bipennate (43.75%), non-pennate (36.25%), unipennate (15%) and multipennate (5%) (Łukasz Olewnik, Nicol Zielinska, Friedrich Paulsen, Michał Podgórski, Robert Haładaj, Piotr Karauda, Michał Polguj. Ann Anat
    . 2020 Nov;232:151584. doi: 10.1016/j.aanat.2020.151584. Epub 2020 Aug 15)

  4. Would leg bouncing be another way to do it? It requires less conscious thought/control to pace it and it bounces at 2 or 3x the rate.

  5. So this is how I can bounce my leg for hours without feeling fatigue, it might be annoying for others but now I have a good justification for doing it.

    1. No es rebote de pierna, es levantar el talón de una forma especial, definida. Mira el video.

    2. Your soleus is simply designed for continual use. Over the time span of many hours, a healthy, trained human can gradually catch an antelope. Think about all of the soleus contractions that requires. Humans are some of nature’s best-designed organisms for rapid, long-distance overland travel. Of course, each step requires a soleus muscle contraction. This evolutionary aspect is a key factor in why you can bounce your leg for hours.

  6. So this might explain why, at 32, my metabolism doesn’t seem to have waned with age, like the rest of my IT-sedentary co-workers. I’m constantly moving my legs up-and-down, in a seemingly similar fashion to what was described above, and still weigh in as much as I did in highschool. The nights I have restless leg syndrome leave me absolutely famished and anemic next morning, too. Perhaps the twitchy are twiggy for this reason…

  7. Umm, what makes the soleus ‘special’ exactly? It’s a slow twitch muscle in the lower leg, one of the calves.

    I wouldn’t expect a neurosciencenews site to need clickbait but here we are.

      1. The article does not actually say how the muscle does this (what biochemical mechanism). It repeats the claims of what, not a deeply explained how.

    1. Any single study that is not corroborated yet is getting this glowing kind of promotion is highly suspect. The first paragraph even reads like the script of an infomercial. I won’t be holding out with excitement for the day this research is even replicated once.

    1. They did a total of 270 minutes, 4.5 hours of it over 7-8 hours of sitting.

      Totally irrelevant finding in a practical sense. That this website left out that bit of data is fascinating. They don’t want people to realize that this means nothing.

      1. Hey, I can focus for 270 minutes on doing calf raises instead of focusing on the task I’m working on in order to increase my metabolism…. uh…. What’s the difference between this and NEAT? You were writing about this a long time ago weren’t you, in I think it was the Rapid Fat Loss Handbook? Can there really be a specific way to contract a muscle that would be more metabolically significant than a combination of normal moving around, even if purposely as in “get up from your desk from time to time and move your body”?

      1. Is not about the motion of the muscle; otherwise is the muscle’d triggering effect producing a chemical in the blood (oxidative?) Necessary for the benefits above mentioned.

      2. A walking desk would achieve 10 times this completely impractical approach to the problem of extended sitting.

        If you do the math they did 450 calories in 270 minutes. That’s about 4.5 miles of walking or so. On a walking desk at 2mph you can do that in 2.5 hours. And you can work at the same time without having to remember to do calf raises every 4 minutes. Walk on that desk for the same 8 hour shift and you can triple the calorie burn.

        And I was writing about most of this 18 years ago.

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