Here at String Visions, the term “String Theory” encapsulates the intersection of science and string playing. By definition, this is about the latest research findings in a number of scientific disciplines, all of which have a direct impact on string playing and string teaching. However, this simple-sounding category encompasses an incredible breadth of topics, with disciplines such as physics and string acoustics, sports science and motor learning, and kinesiology. String Visions will provide a link between string players and leading scientists in various disciplines through articles, interviews, and discussions. This will not only allow us to reach a deeper understanding and awareness of the sciences that have a direct impact on string playing, but will also give us exposure to the latest discoveries in these fields, helping us to become more informed teachers and better players.
The science involved in the vibration of the bowed string is the only well-understood example of vibration excited by friction.  However, a number of the important and fascinating discoveries by scientists in string acoustics have not been fully integrated into the general understanding and vocabulary of string teaching
In sports training centers all over the world a lot of time and money is invested into research about sports science. The study of sports science incorporates areas of physiology, psychology, motor control, and biomechanics, all of which are important to musicians. The physical aspect of playing an instrument has a tremendous amount of similarity to a great number of sports disciplines. There is so much that musicians can learn from the latest research in sports science.
Motor learning can be defined as the process of improving the motor skills – the smoothness and efficiency of movements – in order to master a particular task. As an area of research it has held a very important position in both physical education and psychology for more than 100 years. Many scientific experiments have taken place over the years, controlled by leading scientists in motor learning. To take a case in point, blocked practice has often been compared to random practice in scientific studies. Blocked practice involves giving total focus to one aspect of technique, practicing the same thing over and over until it is correct. Random practice on the other hand is where a number of skills are practiced in random order, with the goal of avoiding or minimizing repetition of any single task. While it is encouraged for musicians to use both methods, random practice has been proven by numerous experiments to be much more effective for long term retention. The idea of repeating a skill over and over is often a waste of time and has been proven to be less efficient in terms of practice technique. This point can be summed up in the words of the late Russian physiologist N.I. Bernstein:
The process of practice towards the achievement of new motor habits essentially consists in the gradual success of a search for optimal motor solutions to the appropriate problems. Because of this, practice, when properly undertaken, does not consist in repeating the means of solution of a motor problem time after time, but in the process of solving this problem again and again. 
Kinesiology, derived from the Greek words kinesis (movement) and kinein (to move), also known as human kinetics, is the science of human movement. Over the years I have read as many books about string teaching as possible. One of the books that had the most profound influence on me as a young teacher was: “The teaching of action in string playing” by Paul Rolland. In that book there are numerous examples of specific practice and performing techniques where string players can learn a tremendous amount from knowledge gained from kinesiology. One example is:
The speed at which a skill is first practiced should be approximately that of the speed at which it is to be used later. 
That quote is one of the most important aspects of instrumental practice. If the end goal is not clear in the mind of the performer, then practicing is a waste of time. In order to master a fast passage it has to be practiced fast in order to find the most efficient movement pattern. In addition the muscles involved with executing a fast movement is completely different than the muscles involved in executing a slow movement.
Kinesiologists work in the fields of sciences that relate to human movement, as well as in fitness and sport, occupational therapy and the movie animation industry. This discipline incorporates special equipment to measure human movement, including optical cameras or electromagnetic sensors in 3-dimensional space or in the 2-dimensional plane to measure telemetry. There are a great number of scientific discoveries that we can incorporate into our instrumental teaching and understanding from research in kinesiology.
Look at the video below to see how motion capture systems can be used to visualize bowing gestures in violin playing. The circular bowing gestures and the figure 8 bowings are very easy to observe. This experiment was supervised by Erwin Schoonderwaldt a brilliant scientist from Sweden who at the present time is a postdoctoral fellow at the Institute of Music Physiology and Musicians Medicine in Hannover, Germany.
The Constrained Action Hypothesis refers to knowledge gained from measuring EMG (Electromyography) activity in performers muscles.  EMG clearly shows in numerous experiments that when performers utilize an internal focus of attention they constrain and interfere with automatic control processes that would normally regulate the movement, whereas an external focus of attention (focus on the movement effect) allows the motor system to more naturally self-organize.  Although many musicians intuitively understand this process, recognizing the scientific fact makes it much more powerful.
 Woodhouse, Jim and PM Galluzzo. “The Bowed String As We Know It Today.” Acta Acustica United with Acustica 90 (2004): 579-589. http://www-acad.sheridanc.on.ca/~degazio/AboutMeFolder/MusicPages/VL%20Docs/BowedStringReview.pdf.
 Bernstein, Nikolai A. The co-ordination and regulation of movements. Oxford: Pergamon Press, 1967.
 Rolland, Paul. “The teaching of action in string playing: Developmental and remedial techniques for violin and viola.” 2nd ed. Illinois String Research Associates, 2000. Pg. 205. Also see the film series based off of the same material at http://www.paulrolland.net/.
 McNevin, Nancy H., Charles H. Shea, and Gabriele Wulf. “Increasing the distance of an external focus of attention enhances learning.” Psychological Research 67 (2003): 22-29. Link.
 Wulf, Gabriele, Barbara Lauterbach, and Tonya Toole. “The learning advantages of an external focus of attention in golf.” Research Quarterly for Exercise and Sport 70 (1999): 120-126. http://www.csuchico.edu/~tciapponi/pdf/W,%20L%20and%20T.pdf