When I came across an Instagram Reel about a muscle that could burn fat and glucose while sitting and working at the desk, or watching a show on television, I was sceptical. But it was posted by an MD in Metabolic Health, and that was reason enough to delve deeper into whether it actually worked. The muscle in question is the soleus muscle (the word is derived from the Latin term solea which means sandal).
Starting at the back of your shin bone and attaching to your heel bone as part of the Achilles tendon, the soleus muscle is vital when it comes to performing basic functions such as walking, running, and jumping. But here’s the big catch: research done by a professor of Health and Human Performance at the University of Houston named Marc Hamilton shows that when worked and activated in the right way, the soleus muscle can help burn calories for hours through the day, lower blood sugar, and also reduce the risk for Type 2 diabetes. The video below, on the official University of Houston YouTube channel, has Hamilton explain his research.
The paper, published in August 2022, also had contributions from scientists Deborah Hamilton and Theodore Zderic and is titled A Potent Physiological Method To Magnify And Sustain Soleus Oxidative Metabolism Improves Glucose And Lipid Regulation. Thankfully, the exercise Hamilton suggests is way simpler than the title of the paper. And it relies on the special ability of this muscle to function slightly differently compared to the others in the human body. “Unlike most muscles, which use stored carbs (glycogen) for fuel, the soleus uses a mixture of other fuels, including glucose and fat, for energy. This lower reliance on glycogen is what helps it work for hours without fatiguing,” states a Honehealth article that summarises the research.
The exercise is simply known as the soleus push-up. It’s a kind of a sitting calf raise. The key is that the knee has to be flexed while performing it. The exercise can be explained in three simple steps: sit with your feet flat on the floor, raise your heels until it reaches the end of its range, and let them fall back to the floor. That’s it. No wonder that the research is finally catching on, via popular social media. It’s almost like this is what we have been searching for forever: An exercise with minimal effort and a lot of benefits.
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The immediate question that one might ask is why walking does not have the same effect as this basic exercise. That is down to the anatomical behaviour of the soleus. Oddly enough, while walking, the body tends to reduce the amount of work that muscle does. That means it needs to be isolated for specific activity for it to start burning those calories.
“That’s part of the secret sauce to this, is that instead when doing this activity, the muscle is simultaneously shortening, while the motor neurons are activated intensely. With walking, the exact opposite is happening in that the muscle is turned off once the heel starts to rise,” Hamilton says in the video explaining the dynamics of the muscle. But like all things that sound too good to be true, the jury’s still out on how long one has to do soleus pushups for.
Even though the paper says that “volunteers all responded well to the prolonged contractile activity and did not experience fatigue or other adverse responses to the prolonged contractile activity, such as cramps, joint pain, or muscle soreness”, it had people doing it for three to four hours at the rate of 50 times per minute without breaks longer than four minutes. Given that this muscle does not rely on glycogen, it didn’t get fatigued, but is it possible to pull this off on a regular basis? It doesn’t seem so.
There is no problem getting excited about the soleus push-up research, but with fitness, the cliche that there are no short-cuts is unfortunately true. A search on the internet brings up aMedium article in which the author claims to have lost 1kg by doing 10 sets of 100 soleus pushups every day for a month without actively reducing his calorie intake. But these examples are few and the same kind of commitment would rather be used to create a more well-rounded fitness routine that focuses on strength, hypertrophy, mobility, and cardio.
Pulasta Dhar is a football commentator and writer.