Asymmetry of the Human Body in Space
Nowadays there are a lot of facts of asymmetry of morphological, functional and biomechanical indices on the front and transversal planes in comparison with the sagittal plane. It is know that the gravitation force is a standing factor of the environment. In anatomy and physiology there is the concept "antigravitative muscles". This term is used to denote the muscles of the lower limbs, counteracting the gravitation force.
Kozlov, I.M. Asymmetry of the Human Body in Space / I.M. Kozlov, A.V. Samsonova, V.S. Stepanov //Acta of Bioengineering and Biomechanics Proceedings of the 13-th conference of European Society of Biomechanics //Wroclaw, 2002.
Kozlov I.M., Samsonova A.V., Stepanov V.S.
ASYMMETRY OF THE HUMAN BODY IN SPACE
Keywords sports biomechanics, asymmetry in space, human movement
The lows of symmetry are widespread in nature. We apply a system approach, founded on the principles of symmetry to the human body. In the point called a common mass center (CMC) three common perpendicular planes are intersected: sagittal, frontal and transversal, fig. 1.
Three planes divide the human body into right and left, front and back, upper and halves. Only the sagittal plane is considered to be the plane of symmetry, at the same time the front and transversal planes don't possess this quality, fig. 2. However in most researches in the field of physical activities and sport (E.P. Ilyin, 1963; N.N. Bragina, T.A. Dobrokhotova, 1981; K.D. Chermit, 1992; V.M. Lebedev, 1992) the problems of asymmetry were viewed mainly in terms of the left and right preferences (the sagittal plane), i.e. where the least asymmetry is pronounced.
Nowadays there are a lot of facts of asymmetry of morphological, functional and biomechanical indices on the front and transversal planes in comparison with the sagittal plane. It is know that the gravitation force is a standing factor of the environment. In anatomy and physiology there is the concept "antigravitative muscles". This term is used to denote the muscles of the lower limbs, counteracting the gravitation force. The physiological diameter of the antigravitative muscles (I.M. Sechenov, 1905; P.F. Lesgaft, 1905; M.F. Ivanitsky, 1929; G. Schumacher, E. Wolff, 1966) exceeds a similar index of their antagonists. Therefore there is a large asymmetry of morphological indices of the muscles of lower limbs to the front plane.
Biomechanical factors of the interaction of the human body with the outer force field affected substantially the formation of the differences in the upper and lower halves of the body. The arms, that is to say, are in the position of "upper support", the gravity force affects uniformly the flexors and extensors. The legs, on the contrary, interact with the gravity force being on the lower support. Morphological differences are shown when the diameters of the flexors and extensors of the muscles of the upper and lower limbs are compared. There are no great differences between the physiological diameter of flexors and extensors. As to the muscles of the legs the difference is substantial.
Consequently, there is a pronounced asymmetry of the human body relative to the transversal plane.
In conclusion it should be noted that this approach gives the possibility to receive a new fundamental knowledge of the laws of the formation of the efficient motor action structures and the deep individualization of the sport and technical training process.
Dr. Alla Samsonova
Dep. of Biomechanics of the Lesgaft State Academy of Physical Education, Decabristov 35 St.Petersburg, 190121, RUSSIA