Kinematyczna Analiza Elementu “Grand Pas De Chat”
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Kinematic analysis of the “Grand pas de chat” element J. Gorwa1, L. B. Dworak1, J. Jurkojć2, R. Michnik2, D. Tejszerska2 1 Department of Biomechanics, University School of Physical Education in Poznan 2 Department of Applied Mechanics. Silesian University of Technology, Gliwice 1. Introduction Current research shows that some of dancing movements, specially during the landing phase (during the eccentric phase of muscle work related to amortization) produce high values of the vertical component of ground reaction force, able to reach the level of 9.4 BW (Picon, 2002; Dworak, 2004; Gorwa et al. 2008). Serious injuries often happen during these phases of jumps. As reported by Luke et al. (2000), Solomon et al. (1995, 1996), Liederbach in: Brownstein and Bronner (1984), the largest percentage of post-traumatic injuries that occur in the circles of professional dancers are chronic injuries such as: inflammatory conditions of soft tissues, overload injuries, muscle strains and tears. Various authors report on different location and percent share of injuries (Micheli, (1983), Brown and Kaufer, (1971); DeMann, (1994); Solomon, (1986); Świderska, (1995)), Gorwa (2008). Nevertheless, the ankle joint, the foot, the spine, the hip and the knee joints are regions that are mentioned most frequently. Since correct technique is a factor that significantly lowers the risk of injuries, and the degree of control of movement habits, that is the appropriate execution of a particular sports technique, determines the force values observed during the landing phase (Rutkowska-Kucharska et al. (2004)), the authors of this study assessed the kinematic values as well as recorded the technique of performing the „grand pas de chat” classical dance element . This jump, belonging to the family of the so called "grand jumps" of classical ballet, in previous tests (Gorwa, 2008) generated the highest vertical components of ground reaction (7.47 BW for a female dancer and 9.43 for a male dancer). 2. Methods The tests used in this study were performed in the Biomechanical Laboratory of the Department of Biomechanics at the University School of Physical Education in Poznan. The tests were carried out on two participants working as professional classical dancers (a female and a male). Each participant performed the „grand pas de chat” element - a jump imitating a delicate, graceful jump of a cat. Fig. 1 Location of the markers: R MT - head of the metatarsal bone of the second toe of the right limb, R HEEL - the calcanean tuber of the right limb, R LMAL - center of the lateral malleolus of the right limb, R TIB - right tibia, R LCON - lateral epicondyle of the left femur, R THI - right thigh, R GTRO - greater trochanter of the right femur, L ASIS - left anterior superior iliac spine, R ASIS - anterior superior iliac spine, SACR – L5S1. The dancers performed the movements barefoot. During the experimental measurements kinematic values as well as line graphs of ground reaction forces were determined. The kinematic values were determined with the use of the APAS motion analysis system, ground reaction forces were measured with the use of the Kistler dynamometric platforms. The motion of the participants was recorded with four Basler digital cameras with the sampling rate of 200 Hz. The images recorded by the cameras were transmitted to a computer where the films were processed with the APAS software and the locations of the markers attached to the tested dancers were determined. At the same time ground reaction forces during the landing phase were recorded. Due to the spaciousness of the performed dancing maneuvers the cameras were positioned in a way that permitted a detailed observation of pelvis kinematics as well as the right lower limb during the landing phase. The number of markers as well as their location (Fig. 1), allowed the authors to determine the centers of the lower limb joints, and then the 77 relative angular motion of individual segments of the lower limb and the pelvis. The calculations were performed with the use of a proprietary software developed in the Matlab environment. 3. Results On the basis of the measurement results it was possible to assess the movements performed by the dancers by observing the graphs of ground reaction forces as well as the graphs of angles in the lower limb joints. Fig. 2 Graphs showing the tilt angle of the pelvis in the sagittal plane for a) female dancer and b) male dancer Analyzing the graphs of ground reaction forces the authors observed high values of ground reaction forces (4.92BW – for the female and 4.75BW - for the male). The duration times of the landing phase in case of classical dancing movements are very short. The authors also observed significant tilt of the pelvis in the sagittal plane during the landing phase (Fig. 2), ranging from -5o to 35o for the female dancer and from 2o to 37o for the male dancer. The analyzed dancing movements included rotational movements of the body along the long axis. The change in the pelvis rotation angle during the landing phase equaled 68o for the female dancer and 50o for the male dancer, whereas the change in the angle of the foot in relation to the vertical axis was little. Analyzing the graphs of joint angles in the sagittal plane, one can observe that they have a similar shape but differ in the range of motion. It concerns in particular the angle in the hip joint. The range of motion in the hip joint equaled 76o for the female and 62o for the male. In case of the knee joint, the range of motion equaled 32o for the female dancer and 23o for the male dancer. The range of motion in the sagittal plane for the ankle joint equaled in case of the female dancer 87o, and in case of the male dancer 52o.. 4. Discussion The testing methodology presented in this study allows for simultaneous determination of kinematics of movements performed by dancers as well as ground reaction forces. It enables one to analyze the influence of the technique of the performed movements on the values of external loads (ground reaction forces). References [1] Picon A., Lobo da Costa P., De Sousa F., De Sacco I., Amadio A. (2000) Biomechanical approach to ballet movements: a preliminary study. ISBS, Hong Kong, 472-475. [2] Dworak L.B., Gorwa J., Kmiecik K., Mączyński J. (2005) A study characterizing dynamic overloads of professional dancers. Biomechanical approach. Acta of Bioengineering and Biomechanics, 7(1), 77-84. [3] Gorwa J.(2008) Dynamic overloads and biomechanical profile of classical and modern dance dancers. Doctoral thesis. [4] Luke A., Kinney S., Dhemecourt P., Baum J., Owen M., Micheli L. (2000) Determinants of injuries in young dancers. Medical Problems of Performing Artists, 8, 105-112. [5] Solomon R., Micheli L.J., Solomon J. (1995) The „cost" of injuries in a professional ballet company. Medical Problems of Performing Artists, 10, 3-10. [6] Solomon R., Micheli L.J., Solomon J., Kelley T. (1996) The „cost" of injuries in a professional ballet company. A three year perspective. Medical Problems of Performing Artists, 9, 67- 74. [7] Liederbach M. (1984) Movement and function in dance. In Brownstein B., Bronner S. Evaluation, treatment and outcomes in orthopedic and sports physical, 8, 253- 310. [8] Micheli L. (1983) Back injuries in dancers. Clinical Journal of Sports Medicine, 2(3), 473-484. [9] Brown T., Kaufer H. (1971) Mechanical function of the patella. Journal of Bone Joint Surgery, 53A, 1551-1560. [10] DeMann L. (1997) Sacroiliac dysfunction in dancers with low back pain. Manual Therapy, 2(1), 2-10. [11] Świderska K. (1995) Zdrowie tancerzy (Dancer health), University of Music in Warsaw. [12] Rutkowska- Kucharska A., Bober T., Serafin R. (2004) The loads acting on the locomotive system in sports. W: Edited by Maciej Nałęcz, Biocybernetyka i Inżynieria Biomedyczna (Biocybernetics and Biomedical Engineering. 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