When I am training clients, I have always touched the muscle at hand as I believe that it helps the client focus on the muscle better and hence, use that muscle more than surrounding muscles that we are not interested in strengthening at the moment.
Is there any science to back that up?
Just today, I found an article from Dr. Gabe Mirkin where he mentions a study by Guang H Yue of the Cleveland Clinic presented to the Society of Neuroscience at San Diego, December, 2001. The study shows that thinking about strengthening muscles makes them stronger. Volunteers thought about contracting muscles controlling their fingers and elbows fifty times in a row, five days a week. After 12 weeks, the fingers were strengthened 35 percent and the elbows, 13.5 percent. How can this be?
Muscles are made of millions of fibers. When you contract a muscle, you use only about one percent at the same time. You become stronger by enlarging muscle fibers and by being able to contract a greater percentage of muscle fibers at the same time. Thinking about exercising did not enlarge the muscles but thinking about muscles helps your brain contract a greater percentage of fibers at the same time. That’s why an athlete who has a broken arm can strengthen that arm by lifting weights with the other arm, but he cannot strengthen that arm by exercising his legs. It’s called cross transference.
So the inference is that touching the muscle makes the client think of the correct muscle to contract. Hence, the muscle will become stronger because it is contracting a great percentage of fibers at the same time. I am so happy I found this!