A lightbulb flashed brightly in my brain when I read a new scientific study about muscle activity and its role in healthy metabolism.
Muscles aren’t just for moving your skeleton. They also affect body composition, including the all-important level of visceral fat, and the potential to develop metabolic syndrome or type 2 diabetes.
Sadly, many Americans sit for nine or more hours a day, and a sedentary lifestyle carries a huge health risk. Even if you exercise vigorously, you can’t entirely counterbalance the negative effects of prolonged sitting.
As a result of their research in this area, Dr. Mark Hamilton and his team at the University of Houston came up with a novel way to enjoy the health benefits of muscle activation even when you’re sitting.
Muscles are not created equal
Different muscles (and the individual muscle fibers within each muscle) follow one of two basic strategies.
Some are fast-twitch fibers which respond quickly to a stimulus but also fatigue quickly. The other type of muscle fiber, the slow-twitch, is more sluggish responding but can sustain action over a longer period of time.
Each muscle is a mix of these different fiber types. The ratio between the two types will vary based on your exercise habits, and will also shift with the aging process. But certain muscles have a preponderance of one fiber type versus the other based on the job that muscle has to do.
The feeding habits of your muscles
Fast and slow twitchers use different strategies for accessing the energy they need to contract.
Fast-twitch muscles preferentially use their stores of glycogen without initially having to pull glucose from the blood stream. The glycogen is already locked into the muscle tissue, so the energy is quickly accessed. Marathon runners who “carbohydrate load” before a big event are trying to force-feed their muscles and store maximal amounts of glycogen before they line up at the starting line.
Slow-twitch muscles, on the other hand, barely use any stored glycogen for their ongoing, steady-state activity. Instead, they absorb fats and sugars (glucose) from the blood stream for their energy needs.
That’s what you want
You want your muscles to burn fat for energy, so you’ll lose fat and have a leaner overall body composition. And you want your muscles to absorb glucose from the blood stream, to keep your blood sugar levels under control.
Secret of the soleus muscle
The soleus muscle forms the bulk of your calf. It’s responsible for the ongoing job of keeping you upright when you’re standing, so it typically has about 80% slow-twitch fibers, about the highest percentage of any muscle group. Even though it’s not a huge muscle, it probably has the largest mass of slow-twitch fibers of any muscle in the body.
Dr. Hamilton studied a way to activate this muscle repeatedly while you’re sitting. It doesn’t get fatigued, because its slow twitch fibers are designed to stay the course. The secret sauce is that the soleus, though only a small fraction of your overall muscle mass, is a reasonably large fraction of your total slow-twitch muscle mass.
And his team showed that activating this muscle created enormous metabolic benefit. You’ll get a much better blood lipid profile and much more efficient blood glucose uptake.
Even better, the benefits didn’t cease when the exercise ended. Subjects experienced improved metabolism for several hours after they finished exercising.
Put this to work for yourself
While you’re sitting, you can perform “soleus push-ups.”
Start with your feet flat on the floor, and simply raise up your heels as high as they will go. Then lower. Then repeat. You can activate both legs at once, alternate sides, or work the right for a number of reps and then switch to the left. Keep doing this exercise consistently throughout your day multiple times.
You don’t have to move at a super fast speed. It’s more important to have a full range of motion — lift your heel as high as you can.
It’s that simple.
For these experiments, Dr. Hamilton’s subjects performed soleus push-ups for 3 to 4 1/2 hours over the course of 7-8 hours. Given the potential distractions throughout your work day, that may not be realistic for you. Just do the best you can. Your results may not be as dramatic as those measured in these experiments, but you’ll likely reap significant benefits nonetheless.