چکیده (انگلیسی):

The knowledge of the actual center of mass (CoM) position enables an estimation of human motion concerning cause-and-effect relations, e.g. using the principles of linear momentum. Although previous analytical methods are able to calculate the CoM, but its precision strongly depends on the quality of the used models and body segments inertial characteristics. Experimental methods provide a more precise location of body’s CoM, but often only in one dimension or with inadequate measurement errors. The aim of this study is primary (i) to show an experimental setup to determine swimmer’s CoM in 2D (sagittal plane) with small errors of the setup and secondary (ii) to show the location as well as (iii) the variation of swimmer’s CoM for different characteristic positions during an undulatory kick cycle. Five female and five male sport students imitated five different positions of an undulatory swimming kick cycle laying sagittal on a triangular platform. The presented method allows to determine the CoM of swimmer’s actual position with measurement errors of maximum 4 cm. Horizontal and vertical position of the CoM as well as the Euclidean distance significantly differs from the hip for all participants and during all investigated phases of a kick cycle.