The mind-muscle connection may hold the key to the effectiveness of this popular training belief.
Muscle confusion—the idea that if you change your workout, you can shock your muscles and achieve better results, or make you leaner, stronger, faster, etc. Basically, by stimulating the muscle differently, you break its training habit, or its automatic response to exercise.
But how does it work, and is it a strategy for performance?
What’s really happening
First, here’s a bit of an anatomy lesson. Our muscular and nervous systems are tied together during activity. There are 650 muscles in our body. Though not all of them help us run, jump, lift and squat, all are under the control of the nervous system. Now that nervous system consists of the brain, spinal cord and billions of neurons—a type of cell that communicates with one another to monitor and regulate the body’s functions. Neurons are part of the peripheral nervous system (PNS) because they extend out from the spinal cord, which together with the brain make up the central nervous system, aka CNS. For every movement we do, these collective nervous systems are communicating with our muscles to react. In most cases, we don’t even realize it.
So for activities that we do every day, like picking up an object, there is a coordinated effort going on between multiple muscle groups, in which our conscious mind tells our CNS a command that it translates in an electrical impulse that is sent through the PNS to the motor neurons responsible for controlling the necessary muscles. When the message arrives, a chemical reaction stimulates the muscle fibers causing them to contract. The whole process takes a millisecond.
We know that exercise makes not just our muscles fit but our nerves fit by increasing the production of proteins that aid and enhance communication between the nervous and muscular systems, according to a 2014 Basel University study published in “Nature Communications.” Specifically, the protein PGC1α plays a key role in the adaptation of the muscle by regulating the genes that cause the muscles to change accordingly to meet the more demanding requirements. When muscle is inactive or ill, only a low concentration of PGC1α is present. However, when the muscle is challenged, the PGC1α level increases. It is this increase that improves the nerve connections to the result of this feedback from muscle to the motor neuron: The health of the synapse (the connection between the nerve and muscle fiber) improves and its activation pattern adapts to meet the requirements of the muscle.
And it is what we know about how our brain works and communicates with these muscles that lays the secret to how muscle confusion may work.
Before you even lift a weight …
Whether we’re grabbing a dumbbell from the stack or placing plates on a bar or attaching a D handle to a cable, the brain is starting to psych our muscles for the work ahead. And since these are exercise that we do regularly, our body knows how to prepare. “The more that we do a task, less effort is required to execute the brain’s commands; however, the requirements to carry out those orders remain constant. We are physiologically efficient, and our muscles are proficient at training,” says Brad Hatfield, Ph.D., a professor of kinesiology with an appointment in neuroscience at the University of Maryland (College Park).
At least that is what research tells us. A study that looked at the effects of psyching may help illustrate this point—and not because of what it found but what it didn’t. When Hatfield and colleagues recorded the muscle activity along the spines of 15 strength-trained men both after the subjects psyched up for a lift and after they did a distraction task like mental arithmetic, they found no difference in performance—though there is some research that has found the opposite. Why the difference? Hatfield thinks it was the subjects—trained men. “My feeling is that in both conditions, the subjects psyched,” he says. “The difference is that in one group, they had a few seconds to do it, and in the other, they did it instantaneously. I think if we did this study with beginners, then we might see a difference.”
This leads to the most consistent findings in the research: “Untrained athletes doing dynamic movements are likely to produce more force and have better muscular endurance,” says David Tod, Ph.D., of the Centre for Rehabilitation, Exercise and Sport Science at Victoria University in Australia. “The reason: They aren’t used to it.”
Dictating the muscle-nerve conversation
How we stimulate the muscle changes how the nervous system communicates with the muscular system, says a 2015 “Journal of Sports Sciences: Muscle and Nerve” study.
When looking at the brains and, in this case, the quadriceps muscles of people who participated in endurance training, strength training or no training communicate differently depending on the activity, University of Kansas researchers found that the quadriceps muscle fibers of the endurance trainers fired more rapidly. “The communication between the endurance trainers’ brains and their muscles was slightly different from the resistance trainers and sedentary individuals,” says Trent Herda, Ph.D., an assistant professor of health, sport and exercise sciences.
“While it is not immediately clear why the communication between the brain and muscle was different as a result of different types of exercise as evidenced by the difference in rates of muscle fibers firing,” Herda says, “the findings suggest that the human body’s neuromuscular system may be more naturally inclined to adapt to aerobic exercise than resistance training for strength as the communication between the brain and muscles was similar between resistance training and sedentary individuals.”
So can muscles really be confused? No. Simulated differently? Of course we know that our nerves and muscles communicate differently when learning new movements or performing different types of exercises.
Neuromuscular research also shows us that putting your mind back to the task at hand may also alleviate your muscles’ training tedium. Instead of thinking about work or anything else that could grab your attention, a honed focus to the task at hand can yield a measurable outcome, according to a study published in the “Journal of Strength and Conditioning Research.” Researchers investigated the effect of psyching up on force production during the bench press by having 12 men and eight women who strength-trained perform five bench-press repetitions either after being distracted, paying attention or psyching themselves up however they chose. Peak force recorded after psyching up was 11.8 percent greater compared to distractions and 8.1 percent greater compared to attention.
The bottom line: While exercise science studies using MRI show us that different exercises activate muscles differently, what makes a true difference is bringing attention and focus to our workout, or doing one that’s completely new to you.
Photo credit: 123RF, IEGOR LIASHENKO