Motor imagery: Can the mind flex the muscle?

In the practice of motor imagery, a person imagines performing an exercise, without actually moving a muscle. The exercise must be imagined in great detail, for best results. If the exercise is a push-up, one would need to recreate in the mind every action needed for a push-up, and then perform multiple repetitions.

Now, before you throw away your dumbbells, a few riders. Motor imagery must be combined with some actual strength training and exercise. (Interestingly, the combination of exercise and motor imagery, in limited-scope studies, has shown better results than exercise alone.) The second rider: Motor imagery cannot work effectively if the activity one is imagining is not an activity one has actually performed. The degree of detail with which the mind recreates the movements is crucial. Some psychologists say it even helps to practice motor imagery in a gym or other such space that one would use for the actual exercise.

So, how does it work? A 2016 experiment, conducted by University of Northampton biomechanics professor Tony Kay, in association with BBC for the TV series Trust Me, I’m A Doctor, tested the effects of motor imagery on a group of seven people with a sedentary lifestyle, who did not exercise for more than two hours a week.

Kay measured calf strength, thickness and the percentage of calf muscle that they were actually using. Then, for four weeks, he asked them to imagine contracting their calf muscles as vividly as possible, 50 times, for 15 minutes a day, four days a week. By the end of the four weeks, the group’s calf muscle strength had risen by an average of 8.1%.

The participants did not actually contract their muscles any more than usual in this time. Calf muscle size remained almost the same. What changed was the percentage of muscle being used.

“They went from using an average of only 46.3% of their muscle before training, to an average of 68.8% of their muscle after training,” Kay states in the series. In essence, he adds, motor imagery acts as a rehearsal of a skill, with the result that the subject gets better at using the same muscles.

It is important to note that the fitness levels of the subjects did not technically change. Essentially, motor imagery can improve strength, but it does not increase fitness.

The use of motor imagery is now being explored in sports medicine. A study by researchers at the University of Glasgow, published last November in the journal Medicine & Science in Sports & Exercise, found that during periods when athletes do not or cannot train physically, motor imagery practice “…seems to be a viable tool to maintain and increase physical performance capacity.”

The study examined the effects of motor imagery on a group of 20 professional basketball players, against a control group that was assigned the same training exercises but no motor imagery. Strength performance in the first group improved by between 2% and 9%.

Could this also be an effective practice for musicians; for surgeons? Could it have applications in motor rehabilitation? A study by University of Cape Town physiotherapist and pain researcher Katleho Limakatso, published in the journal of the Chartered Society of Physiotherapy in 2019, indicates that motor imagery could help ease the pain of phantom limb syndrome.

In Limakatso’s study, 21 adults who had undergone limb amputations were put on a six-week graded motor-imagery programme alongside routine physiotherapy, and reported significantly less phantom limb pain than a control group of 21 who were practising only the physiotherapy. How’s that for mind-bending?