If you’re a physically active person, you know how hard it is to be told that you have to stay off your feet. You might be in a position in which you have to keep a limb immobilized because you sprained it or broke a bone…or maybe you had a major illness or surgery that requires you to stay bedbound and then take it easy for several weeks. You might think that this inactivity is sabotaging your hard-won muscle tone and strength—and it is. But here’s a trick to keep your muscles strong if you do end up “out of commission”—and you needn’t even lift a finger to do it…
It’s about mind over matter. Yes. You can think your way to physical strength, according to a team of researchers from the Ohio Musculoskeletal and Neurological Institute at Ohio University.
The team wanted to test the theory that the nervous system strongly influences muscle strength and weakness. They took 44 healthy adults, all of whom were equally strong (proven by strength-measuring tests), and divided them into three groups. The first group served as the control and went about their ordinary lives. The second group had the wrists of their nondominant hands immobilized in casts for four weeks to intentionally cause muscle weakness. The third group also had their nondominant wrists immobilized for four weeks, but they performed mental imagery training exercises five days per week for those four weeks.
The researchers measured the strength of the study participants’ wrist flexor muscles before, immediately after and one week after immobilization. They also used a combination of transmagnetic stimulation, electromyography, and electrical stimulation to measure voluntary activation, which reflects the nervous system’s ability to fully activate muscle, and corticospinal inhibition (a resting phase of communication between the brain and nervous system), which they have previously shown is prolonged when muscles are weak.
Participants in the mental imagery group performed 52 imagined contractions of their wrist muscles during each training session. For example, they were instructed to imagine contracting the muscles in their forearms as hard as they could or imagine pushing against a handgrip with all their might. Each mental “exercise” rep lasted for five seconds, with a five-second rest period between reps. The participants had to keep their arm muscles relaxed and engage only their brains as they imagined the movements. Electromyograms were used to document that actual muscle movement was not occurring.
The results: It’s no surprise that immobilization caused loss of strength, impaired voluntary activation and inhibited corticospinal processes in all subjects with immobilized wrists. However, practicing mental imagery cut the degree of strength loss and voluntary-activation impairment in half. Corticospinal inhibition was equally lessened. In other words, the group that visualized exercises maintained 50% more wrist-muscle strength than the group that simply endured having a wrist cast for the four weeks.
These findings, while intriguing, are not an excuse to stop going to the gym or engaging in your favorite exercise. But they do show how powerful your mind can be in keeping your body strong and fit. In fact, top athletes and musicians are known to enhance their performance by practicing in their minds. Envisioning strengthening movements in between workouts, and especially if you are immobilized due to sickness or recuperation, could yield big rewards when you are back in the game.
