Patients who are unable to use their muscles for extended periods of time – such as those who have suffered a stroke – often experience weakened muscles from lack of use. But now, a new study suggests that performing mental imagery exercises can prevent the unused muscles from getting weaker.
The researchers, from the Ohio University Heritage College of Osteopathic Medicine, publish their findings in the Journal of Neurophysiology.
Using mental imagery for physical performance is not necessarily a new concept; professional athletes often use such techniques to improve their athletic performance. However, the team says theirs is the first study to demonstrate that imagery can stop or slow muscle strength loss after long periods of disuse.
The findings have implications for individuals undergoing neurorehabilitation and provide a “major breakthrough” for scientists, in that they offer new evidence about how the nervous system affects muscle weakness.
Though medical scientists have known that the brain’s cortex coordinates and controls muscle movement, until now, the link between the cortex and muscle strength has been up for debate.
“We wanted to tease out the underlying physiology between the nervous system and muscles to better understand the brain’s role in muscle weakness,” says Prof. Brian Clark, study author and director of the Ohio Musculoskeletal and Neurological Institute.
He refers to muscles as the nervous system’s puppets, with the brain acting as the string prompting the muscles to move.
To conduct their study, the team had a group of healthy individuals undergo 4 weeks of wrist-hand immobilization – achieved by wearing a cast – to encourage muscle weakness. Meanwhile, another group also underwent 4 weeks of immobilization, but they performed mental imagery of strong muscle contractions 5 days per week.
In addition, a control group underwent no interventions. Medical News Today did not have access to the number of total subjects who participated in the study. Before, immediately after and 1 week following the immobilization interventions, the researchers measured wrist flexor strength.
As the first group imagined contracting their muscles and flexing their wrist, the researchers recorded their muscle activity using an electromyogram (EMG).
Overall, the results showed that the mental imagery training attenuated the loss of strength. Explaining their findings further, Prof. Clark says:
“What our study suggests is that imagery exercises could be a valuable tool to prevent or slow muscles from becoming weaker when a health problem limits or restricts a person’s mobility.
The most impactful finding, however, is not the direct clinical application, but the support that this work provides for us to better understand the critical importance of the brain in regulating muscle strength. This information may fundamentally change how we think about muscle weakness in the elderly.”
The researchers further say that their findings suggest neurological mechanisms at the cortical level contribute to “disuse-induced weakness,” adding that imagery activating the cortical regions lessens weakness “by maintaining normal levels of inhibition.”
Following on from this study, Prof. Clark and his team will carry out further research on muscle strength loss in a 4-year project funded by the National Institutes of Health’s (NIH) National Institute on Aging.
In October of this year, MNT reported on the development of a new prosthetic arm that is controlled by the brain.