The latest TikTok fitness trend isn’t a new treadmill routine or push-up challenge: It’s seated calf raises.
Namely, it utilizes the soleus muscle, which runs from below the knee down to the heel. As published in the journal iScience, researchers from the University of Houston found that doing “soleus pushups” (SPUs)—which involve raising and lowering your heels while seated—can help your body regulate glucose and improve its metabolizing of fat.
TikTokkers have gotten wind of the study, and some have published viral videos about the supposedly easy way to juice your metabolism.
In fact, experts agree that these findings are exciting. Your metabolic processes can slow down when you’re sitting still for long periods of time, so SPUs could be a way to inject an activity that has a meaningful effect into the lives of people who would otherwise be stationary for hours on end.
“The interesting thing here, which I haven’t seen before, is the development of a protocol that could negate some of the negative effects of inactivity while still sitting,” says exercise physiologist Sharon Gam, PhD, CSCS, who was not involved in the study. “That has the potential to be very powerful.”
Some of those negative effects of being stationary include an increased risk of developing diabetes, metabolic syndrome, obesity, heart disease, and other conditions.
Specifically, what the University of Houston study found that SPUs can do is raise your “local oxidative metabolism.” Brittany Masteller, PhD and research scientist at Orangetheory Fitness, who also was not involved in the study, explains that local oxidative metabolism is “how well your body is able to create/use energy.”
An elevated local oxidative metabolism efficiently turns fats and carbs into energy without spiking your glucose in either direction, while a sluggish one processes those molecules less efficiently. (Think about how low-energy you can get from sitting on the couch or at your desk if you don’t move around.) People who spend a lot of time stationary might be interested in raising that metabolism to help regulate blood glucose (or energy levels), burn fat, and ward off metabolic conditions.
“These findings have revealed a potential tool for improving the rate of muscle metabolism during inactivity,” Masteller says.
A low-effort movement you can do while sitting that raises your metabolic activity and could ward off disease? Sounds great! But there are some important things to keep in mind.
Most saliently, Gam points out that the methods of the study involved people doing SPUs continuously for three to four hours at a time, at least 50 times per minute, without stopping for more than four minutes at a time.
“The study did say that people didn’t report discomfort or fatigue from doing this movement for that long, which I’m honestly surprised by,” Gam says. “If I was doing calf raises for four hours, even unloaded using just the weight of my lower legs, I would think I would eventually get tired. But I haven’t tried it so I guess I can’t say for sure.”
The study’s authors explain that these muscles don’t get tired because they don’t rely on glycogen for fuel, as most muscles do.
“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,” says study author Marc Hamilton, professor of health and human performance at the University of Houston.
But Masteller is also skeptical of how doable this method actually is.
“We should be cautious to extrapolate the findings to real-world applications,” she says. “The study was performed in tightly controlled laboratory environments, which is not the same as people performing SPUs at their work desks in a free-living environment.”
The point is, we know from the research that doing three to four hours of continuous seated calf raises has the potential to fire up our glucose-regulating metabolism. But we don’t know about the possible effects of doing anything less than that, let alone doing SPUs on our own outside of the carefully constructed confines of a lab.
Gam sees SPUs as “a good tool to add to the toolbox in terms of ways to reduce health risks.” But is it a metabolism firing, fat-burning magic bullet? Well, in fitness, if it sounds too good to be true, it probably is. In the case of the soleus pushup, it’s a classic case of promising research getting oversimplified and overstated for social media. A tale as old as time (or at least, as old as TikTok).