Changes in the Force Produced by the Fingers of the Hand and Their Interdependence in Isometric Tasks. Summary of the Doctoral Thesis
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Date
2022
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Latvian Academy of Sport Education
Abstract
Motor control is the process of initiating, executing, and grading voluntary movements (Medical Dictionary for the Health Professions and Nursing). It studies how the nervous system interacts with the human body and the environment to provide coordinated movements (Latash, 2012). Motor control has evolved rapidly over the last decades and has separated from neurophysiology and biomechanics as a distinct discipline. Motor control can be traced back to ancient Greece, where philosophers and mathematicians of the time were interested in the movements of the human body and the soul that directs and controls them. Over time, different mechanisms of movement control were explored and understood. In the second century AD, the physician Galen discovered that joint movements are controlled by two opposing pairs of muscles: agonists and antagonists. The study of human movement continued during the Renaissance. Descartes put forward a theory based on the idea that humans are composed of two independent parts, the body and the soul (similar to the ancient Greeks) (Cappozzo & Marchetti, 1992; Latash, 2012). The existence of electricity in human internal processes was discovered in the late eighteenth century, and in the mid-nineteenth century, the German scientist Flugger discovered in experiments on decapitated frogs that the spinal cord could generate meaningful and controlled movements (Verworn, 1907). At the same time, the American scientist Woodworth explored one of the first conclusions about motor control: that control of rapid movement consists of an initial impulse and later corrections. This idea is now often formulated as a combination of feedforward and feedback control processes (Elliott et al. 2001). The founder of motor control is the Russian scientist Nikolai Bernstein, who proved that joints do not work independently but correct each other's mistakes when performing a movement task. He concluded that the human central nervous system does not provide a unique and unambiguous motor solution, but uses the information it receives from the periphery to ensure a more precise execution of the movement task. Bernstein developed the theory of limitation of excess degrees of freedom (kinematic and dynamic abundance): in order to realise a movement task, there are infinitely many possible solutions, so unnecessary or excess degrees of freedom must be limited and mechanically coupled. Bernstein's greatest contribution is the development of the multi-level theory of the motion control system, which consists of five levels: the palaeokinetic level, the synergy and pattern level, the spatial field level, the action level and the symbolic, highly coordinated action level, and their sub-levels. This hierarchical system of movement generation that he developed is still considered the best system because it covers all levels of central nervous system activity (Bernstein 1967; Latash, 2012, 2020). Although motor control has its origins in BC, it is a relatively recent development as a separate scientific discipline. It is a young science and therefore has much unexplored or underexplored potential. One such topic of interest to scientists is the control of the human hand and fingers. It is related to the fact that, for example as a result of a stroke or some neurological disease, the human hand is one of the first to deteriorate in its functional activity (Hunter & Crome, 2002). Finger motor development is also of interest to researchers because the flexor muscles of the four fingers (index, middle, ring and little fingers) have two muscles (m. flexor digitorum superficialis (FDS) and m. flexor digitorum profundus (FDP)) and the extensor muscle of the same fingers has only one muscle (m. extensor digitorum). (Kalberg, 1973; Knipše, et al., 2020). Other muscles, such as m. extensor digiti minimi or m. extensor indicis, also contribute to the functionality of the fingers. There are no muscles in the fingers themselves to flex or abduct them. These facts make the study of fingers both simpler (relatively few muscles are involved in the movement) and more complex (finger differences are probably of neural origin). The joint is normally powered by two muscles with opposite actions. This phenomenon is known as agonist-antagonist coactivation (Smith, 1981). The agonist exerts a force and/or moment of force in the direction of the task, while the antagonist opposes this action. When pressed with the fingertips, the agonist is the external finger flexor muscle - FDP - a multifilament muscle in the forearm and the four tendons located in the distal phalanges of the four fingers (Kalberg, 1973; Knipše, et al., 2020). This shows that the fingers are interconnected by nature, which motor control has only started to study in more depth in the last twenty years. Our publications are a complement to these studies and an attempt to further understand finger control and their interdependence. This new knowledge can serve as a basis for future research directions in sport, as in many sports (e.g. archery, shooting, rock climbing, etc.) finger specialisation is a key factor in achieving high performance.
Description
The Doctoral Thesis was developed at Latvian Academy of Sport Education and Institute of electronics and computer science in cooperation with Pennsylvania State University from 2014 to 2022. Defence: at the public session of the Promotion Council of Health and Sports Sciences on 29 June 2022 at 11.00 in the room 205., LASE (Brivibas gatve 333, Riga).
Keywords
Summary of the Doctoral Thesis, sports medicine, wrist, finger, strength, motor control, movement activity
Citation
Āboliņš, V. 2022. Changes in the Force Produced by the Fingers of the Hand and Their Interdependence in Isometric Tasks: Summary of the Doctoral Thesis: Sub-Sector – Sports theory and history. Rīga: Latvian Academy of Sport Education. https://doi.org/10.25143/prom-rsu-lspa_2022-04_dts