The “special” muscle can promote the burning of glucose and fat to fuel the metabolism for hours while sitting

Summary: The pioneering “soleus flexion” effectively increases muscle metabolism for hours, even while sitting.

Source: University of Houston

From the same mind whose research fueled the idea that “sitting too much is not the same as exercising too little” comes a groundbreaking discovery that will give a sedentary lifestyle its ear: the soleus muscle Calf, although only 1% of your body weight, can do great things to improve the metabolic health of the rest of your body if activated correctly.

And Marc Hamilton, professor of Health and Human Performance at the University of Houston, has discovered this approach to optimal activation: he pioneered the “soleus flexion” (SPU) that effectively increases muscle metabolism for hours, even while sitting. The soleus, one of the 600 muscles in the human body, is a muscle in the back of the leg that runs from below the knee to the heel.

Published in the magazine iScience, Hamilton’s research suggests that the soleus flexion’s ability to maintain elevated oxidative metabolism to improve blood glucose regulation is more effective than any popular method currently touted as a solution that includes exercise, weight loss, and intermittent fasting Oxidative metabolism is the process by which oxygen is used to burn metabolites such as blood glucose or fat, but it depends, in part, on the immediate energy needs of the muscle when it is working.

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

Muscle biopsies revealed that there was a minimal contribution of glycogen to fuel the soleus. Instead of breaking down glycogen, the soleus can use other types of fuel such as blood glucose and fat. Glycogen is typically the predominant type of carbohydrate fueling muscle exercise.

“The lower-than-normal reliance on glycogen in the soleus helps it work for hours without fatigue during this type of muscle activity, because there is a definite limit to muscle endurance caused by glycogen depletion,” he added. . “To our knowledge, this is the first concerted effort to develop a specialized type of contractile activity focused on optimizing human metabolic processes.”

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

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

The Soleus Pushup

Based on years of research, Hamilton and his colleagues developed the soleus flexion, which activates the soleus muscle differently than when standing or walking. SPU targets the soleus to increase oxygen consumption, more than is possible with these other types of soleus activities, while being resistant to fatigue.

Marc Hamilton, Professor of Health and Human Performance at the University of Houston, pioneered the “soleus flexion” for the calf muscle that makes up only 1% of body weight, but can improve the metabolic health of the rest of the body if activated. correctly Credit: University of Houston

So how do you perform a soleus flexion?

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

While the SPU movement may look like walking (even though it’s done sitting down), it’s 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 reverses this and causes the soleus to use as much energy as possible over a long period of time.

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

Additional publications are in the works focusing on how to teach people to properly learn this unique movement, but without the sophisticated lab equipment used in this latest study.

Credit: University of Houston

Researchers are quick to point out that this isn’t a new fitness or diet tip of the month. It is a powerful physiological movement that takes advantage of the unique characteristics of the soleus.

Potential first step towards a breakthrough in health care

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

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

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

Hamilton said inactive muscles require less energy than most people seem to understand, calling it “one of the most fundamental yet overlooked problems” that leads the way toward discovering metabolic solutions to help prevent some chronic diseases associated with age.

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“All 600 muscles combined typically contribute only about 15% of the whole body’s oxidative metabolism in the three hours following carbohydrate ingestion. Although the soleus is only 1% of body weight, it is capable of of increasing your metabolic rate during SPU contractions to easily double, sometimes even triple, whole body carbohydrate oxidation.

We know of no existing or promising pharmaceutical product that comes close to increasing and sustaining whole-body oxidative metabolism to this magnitude.”

About this metabolism research news

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

Original Research: Open access
“A Potent Physiological Method to Increase and Maintain Soleus Oxidative Metabolism Improves Glucose and Lipid Regulation” by Marc Hamilton et al. iScience


A powerful physiological method to increase and maintain soleus oxidative metabolism improves glucose and lipid regulation

Slow oxidative muscle, especially the soleus, is inherently well equipped with the molecular machinery to regulate blood-borne substrates.

However, all human muscle accounts for only 15% of the body’s oxidative metabolism of glucose to energy expenditure at rest, despite being the largest mass of lean tissue in the body.

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

Increasing otherwise negligible local energy expenditure with isolated contractions improved systemic triglyceride and glucose homeostasis by a large magnitude, for example, 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 powerful method to improve systemic metabolic regulation while prolonging the benefits of oxidative metabolism.

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