From Big Medical Encyclopedia

BIOMECHANICS (Greek bios life + mechane the tool, the machine) — the section of biophysics studying mechanical characteristics of living tissues, bodies and an organism in general and also the physical phenomena occurring in them in the course of life activity and movement of a body in space. The term «biomechanics» called also the section of embryology earlier — development mechanics (see. Embryology ). Being based on the data of anatomy and using methods of theoretical and applied mechanics, B. investigates deformations of structural elements of a body, the movement of liquids and gases in a live organism, movements of links of a body relatively each other and all body in space, the stability and controllability of movements and other questions available to methods of mechanics.

B. movements investigates structure of a musculoskeletal system (character of mobile joints, number of degrees of freedom), kinematics of movements (speed, accelerations, trajectories), dynamics of the movements — a picture of operating forces. Most often the problem of a biomechanical research consists in that to determine a picture of operating forces by kinematic characteristics of the movement.

Modern B. is not limited to the analysis of movements. The sphere of appendices B. extends, and now it includes studying of respiratory system, the blood circulatory system, specialized receptors, etc.

B. of the respiratory device studies kinematics and dynamics of the respiratory movements, respiratory resistance caused by friction of air at the movement on a throat, trachea and bronchial tubes (not elastic resistance), resistance connected with elasticity of a thorax, elasticity of tissues of lungs, and also the liquid tension, a thin coat covering alveoluses (elastic resistance). B. blood circulations emergence of acoustic vibrations in cardiovascular system, questions of heat exchange, etc. studies rheological properties of blood, a vascular wall and perivascular fabrics, features of a blood flow in the branching vessels, in vessels of small diameter and capillaries, the hydrodynamic phenomena in cardial cavities and the main vessels.

History. The foundation to researches on B. was laid for Leonardo da Vinci who showed great interest to different types of the movement of the person and animals. Studying flight of birds and the movement of the person, work of skeletal muscles and heart, mechanics of breath and a phonation, he considered that functioning of a row of systems of an organism is subordinated to laws of mechanics.

Considerable impact on B.'s development was exerted by J. Borelli's works; in the book «About the Movement of Animals» it gives the analysis of various movements of a body during the walking, run, swimming from positions of mechanics. Borelli for the first time defined a center of gravity position of a body of the person. Pilot study of walking was conducted by Weber's brothers (E. and W. Weber, 1836). They defined the relation of duration and length of a step, amplitude of vertical movements of a body during the walking, changes of functional length of an extremity during the walking, etc. The invention of the snapshot and cinematography promoted rough blossoming of B. of movements in Germany [Anschutz], France (E. Marey) and America [Maybridzh (E. Muybridge)]. Essential results on biodynamics of locomotions were received it. scientists Brown and Fischer (Cii. W. Braune, O. Fischer), H. Elftnian.

In Russia the foundation of studying of questions B. is laid by I. M. Sechenov's works π P.F. Lesgafta. In «Sketches of labor movements of the person» (1901) I. M. Sechenov gave the report of the major biomechanical characteristics of movements of the person; problems of theoretical anatomy of a musculoskeletal system were developed by P.F. Lesgaft with attraction of data of a comparative anatomy and mechanics. In the USSR in 20 — the 30th years a number of institutes was engaged in applied B.'s questions (for the purpose of rationalization of a workplace, forms of tools, working methods, a working pose etc.) (Central in-t of work. All-Union in-t of economy, Central in-t of work of disabled people). Since 1924 in Leningrad un-those A. A. Ukhtomsky began to give a course of physiology of the motive device where the section B was included. In the book «Physiology of the Motive Device» (1927) he stated extensive material according to B. of muscles, joints and coordination of movements. As an introduction course in B.'s orthopedics N. V. Pariysky read in Rostov medical in-those.

The significant contribution to B.'s development was made by N. A. Bernstein who considerably improved methods of registration and the analysis of movements (a kimotsiklografiya, a tsiklogrammetriya), who carried out the biodynamic analysis of walking of healthy people, its evolution at children and old men, races, jumps, a march etc. In 1938 A. Engelgardt and M. N. Lyubimova for the first time showed existence of communication between mechanical and chemical processes. In a crust, B.'s time it is taught in Ying-those physical culture. There is the international society of biofur nicknames; the International congresses according to B. S are carried out 1968 the international magazine «Biomechanics is issued».

Methods of biomechanical researches include various methods of registration of situation and the movement of a body, measurements of force of groups of muscles, the moments of inertia of links of a body, etc. For studying of position of a body there are devices allowing to define the provision of the general center of gravity in relation to a surface of a support, the size of a basic contour, degree of stability of a body in space. For registration of the movements various options of light record are used. Tsiklografiya (see) consists in registration on a motionless photographic plate of several chosen points of a moving body. Apply to registration of the movements which trajectories can be imposed at each other (e.g., the cyclic movements) kimotsiklografiya (see) — registration of the movements on evenly moving film. The system of processing of cyclograms (tsiklogrammetriya) allows to determine amplitude of the movement, speed and acceleration by the cyclogram. Big distribution was gained by methods of electric registration of biomechanical parameters of the movement. By means of various sensors it is possible to register directly the curve movements in joints, components of basic reactions and a point of application their equally effective, peripheral and angular speeds and accelerations, etc. During the studying of labor movements of the person use special nozzles to the working tool with the sensors allowing to register the size of the enclosed muscular moments in various planes, force of blow, etc. At electric registration of parameters of the movement their direct input in the COMPUTER is possible. It gives the chance of receiving in real time such major indicators of the movement as the moments of forces operating in a joint, work and power.

Value of biomechanics for medicine

Results of biomechanical researches are of interest to physiology and clinical medicine. On the basis of these researches biomechanical characteristics of bodies and systems of an organism which knowledge is the major premises for studying of processes of regulation can be made. B. is of considerable interest to prosthetics, being the principle of design of prosthetic and orthopedic products. Many characteristics of a musculoskeletal system are used at design of other technical systems (see. Bionics ). A number of biomechanical indicators of a condition of blood circulation (e.g., a ballistokardiografiya, a dinamokardiografiya) and breath plays a role of important quantitative indices in diagnosis, in definition of indications and contraindications to heart and lungs operations. Researches B. of breath and blood circulation are used during creation of the device «heart — lungs». Characteristics of durability of bones, joints and sheaves, elastoviscous properties of muscles and other fabrics are of considerable interest to traumatology and orthopedics, to understanding of mechanisms of action of disturbing factors and the prevention of injuries. B.'s studying sports movements and physical exercises opens bases of skill and helps development of evidence-based system of trainings.

B.'s studying labor processes allows to estimate profitability of different options of movements and to improve their structure.

Important problem B. is studying of biomechanical characteristics of fabrics, that is properties of bodies and tissues of the person and the animals who are shown at different types of mechanical influence. Some data on biomechanical characteristics of fabrics became property of applied medicine, use them in prosthetics, traumatology, for definition of optimum loadings at athletes.

Bibliography: Alexander R. Biomekhanika, the lane with English, M., 1970, bibliogr.; Bernstein N. A. General biomechanics, M., 1926, bibliogr.; about N e, About creation of movements, M., 1947; it, Sketches on physiology of movements and physiology of activity, M., 1966, bibliogr.; Researches on biodynamics of locomotions, under the editorship of N. A. Bernstein, M. — JI., 1935; Researches on biodynamics of walking, run, a jump, under the editorship of N. A. Bernstein, M., 1940, bibliogr.; Nikolaev JI. P. The guide to biomechanics in use to orthopedics, traumatology and prosthetics, p.1 — 2, Kiev, 1947 — 1950, bibliogr.; Sechenov I. M. Sketches of labor movements of the person, M., 1901; A. S's Burton. Physiologie und Biophysik des Kreislaufs, V., 1969, Bibliogr.; Frost Η. M. An introduction to biomechanics, Springfield, 1967; Pulsatile blood flow, ed. by E. O. Atinger, N. Y., 1964, bibliogr.; Y a m a d a H. Strength of biological materials, Baltimore, 1970.

Biomechanical characteristics of fabrics — Anikin Yu. M. Physicomechanical properties of vertebrae of the person, Uchen. zap. Mosk. Region ped. in-that, t. 273 — Zoology, century 8, page 12, 1970, bibliogr.; Lesgaft P. F. Fundamentals of theoretical anatomy, p.1, SPb., 1892; About y with about in A. S. Reliability of biological fabrics, M., 1971, bibliogr.; Evans F. G., L i s-s n e r H. R. a. Pedersen H. E. Deformation studies of the femur under dynamic vertical loading, Anat. Rec., v. 101, p-225, 1948, bibliogr.; Trie-p e 1 H. Ober gelbes Bindegewebe, Anat. Anz., Bd 15, S. 300, 1898.

V. S. Gurfinkel.