Predomination of one side of the human body over the other side is a wellknown phenomenon. Various methodical studies reveal bilateral differentation to be a common feature in human motor development. Both endogenous and exogenous fibers are generally thought to form in a bilateral manner. However, the lateralization process has not been fully explained. The asymmetry of the hemispheres of the brain is observed in individual development (ontogenesis) from the fetal period on. Greater efficiency of the right hand as compared with the left hand is a recognized characteristic in the functional asymmetry of man, and similar differences are found in the lower limbs (Szczebiotko, 1975). There is significant asymmetry in the length of the bones of the lower limbs, with preference to the left leg, and differences in the circumference of the thighs and calves (Artemeva, 1964; Czabaiiski, 1975; Drozdowski, 1975). Alterations in the functional scope of the respective limbs, combined with morphological changes, are observed (Kurachenkov, 1966). According to some researchers the right lower limb performs functions that require speed and precision, while the left lower limb is used more often in movements requiring great dynamic strength (Wolanski, 1962; Dolja, 1973; Starosta, 1975). The superiority of the right hand and left leg is a type of lateralization characteristic for women, whereas higher efficiency of the right hand and right leg predominates in men (Koszczyc, 1977). The problem of lateralization is particularly significant in sports: such as running, cycling, and swimming, which are symmetrical in nature. Of special interest here are the leg movements in breaststroke swimming. The human structure is not precisely symmetrical, and most human movements are asymmetricaL The following questions arise: 1. Are the requirements for absolute symmetrical motions justified? 2. Will the attainment of symmetry result in improved swimming performance? The purposes of this study were: 1) to verify the extent of asymmetry in the motion of the lower limbs in the breaststroke, 2) to define possible differences in the degree of asymmetry for women and men, and 3) to examine the relationship between asymmetry and swimming speed, assuming the latter to be the best indicator of swimming efficiency.
© Copyright 1979 Swimming III. Proceedings of the Third International Symposium of Biomechanics in Swimming, University of Alberta, Edmonton, Canada. Published by University Park Press. All rights reserved.