- Email: [email protected]
A 3-D simulation of a soccer kick: The effect of varying hip and knee torques
Abstracts FACTORS ACCOUNTING FOR VARIABILITY IN DISTAL END SPEED IN KICKING Carol Putnam School of PhYslcal Education, Dalhousie University, Hal ifax, Nova Scotia. B3H 3J5 In an effort to understand kinematic and kinetic factors related to the coordination of the lower extremity segments in kicking, a model was developed to identify factors which determine maximum kicking speed. It was found that the variability in kicking speed.demonstrated by 17 skilled performers could be accounted for by variability in the contributions made by the linear motions of the hip and of the ankle relative to the knee (the latter primarily determined by the angular speed of the leg) to the maximum ankle speed. Subjects’ abilities to achieve maximum ankle speed could also be distinguished by the way segments interacted. Specifically, a significant relationship was found between the effect of the thigh’s angular velocity on the leg and maximum kicking speed, confirming the importance of this aspect of the dynamic interaction between segments when attempting to produce high speed movements of linked systems.
A 3-D SIMULATION OF A SOCCER KICK: THE EFFECT OF VARYING HIP AND KNEE TORQUES IDeWitt, J.K., ‘Hinrichs, R.N., and ‘Yamaguchi, ‘Department
of Exercise
G.T.
Science and Physical Education;
‘Department of Chemical, Bio & Materials Engineering, Arizona State University, Tempe, AZ 85287, USA. A 3-D forward dynamic simulation was used to determine the effects of the absence of hip or knee moments on a soccer kick. The rapid reduction of hip flexor torques during a normal kick induced large accelerations upon the shank prior to impact. Knee flexor torques became present during follow through. The absence of knee torques does not markedly change segment actions during a kick, while eliminating hip torques significantly affected the kicking motion. This suggests large angular momentum transfers from the hip to the shank with little momentum transfer from the shank to the hip. It can be concluded that during a soccer kick hip torques are much more important than knee torques in producing desired leg motion,
SESSION e-MATERIAL PROPERTIES OF BONE Chairperson: Joseph E. Hale
BETWEEN MECHANICAL ENVIRONMENT AND COLLAGEN CROSS-LINKING P’N BONE: AN EXAMPLE FROM THE DEER CALCANEUS S.GunPrtrkaron. h.D., Brent Constantz, Ph.D., John Skedros’, M.D., R.D. Bloebaum”, Ph.D. Norian Corporation, Mountain View, CA 94043 and CORRELATION
*Division of Orthopedic Surgery, University of Utah Medical Center, Salt Lake City, UT 84148 The “Trajectorial theory” introduced by Wolf (1870; 1892) and later supported by others has predicted the relationship between bone remodelling and mechanical stresses. These findings
prompted us to determine the possible chemical and mineralogical changes in bone that happen due to mechanical stress. The calcaneus bone (of mule deer) is a relatively simple beam-like skeletal structure that functions as a lever arm which places its cranial(superior) aspect primarily in compressive stress and its caudal (inferior) aspect primarily in tensile stress. A total of twenty calcaneus bones were examined. The samples were tested for mineralogy using XRD and FTIR and for organic analysis using total proteins and amino acids assay. In addition, a new technique was used to assess the level of protein crosslinking. Highly significant differences were observed in the relative amounts of collagen cross-linking between the two bone sections: An average of 24% higher cross-linking of the superior portion was observed compared to the inferior portion. These results may bs interpreted as meaning that the collagen matrix of bone that is under compression becomes more cross-linked to provide greater mechanical rigidity.
661
A 3-D SIMULATION OF A SOCCER KICK: THE EFFECT OF VARYING HIP AND KNEE TORQUES IDeWitt, J.K., ‘Hinrichs, R.N., and ‘Yamaguchi, ‘Department
of Exercise
G.T.
Science and Physical Education;
‘Department of Chemical, Bio & Materials Engineering, Arizona State University, Tempe, AZ 85287, USA. A 3-D forward dynamic simulation was used to determine the effects of the absence of hip or knee moments on a soccer kick. The rapid reduction of hip flexor torques during a normal kick induced large accelerations upon the shank prior to impact. Knee flexor torques became present during follow through. The absence of knee torques does not markedly change segment actions during a kick, while eliminating hip torques significantly affected the kicking motion. This suggests large angular momentum transfers from the hip to the shank with little momentum transfer from the shank to the hip. It can be concluded that during a soccer kick hip torques are much more important than knee torques in producing desired leg motion,
SESSION e-MATERIAL PROPERTIES OF BONE Chairperson: Joseph E. Hale
BETWEEN MECHANICAL ENVIRONMENT AND COLLAGEN CROSS-LINKING P’N BONE: AN EXAMPLE FROM THE DEER CALCANEUS S.GunPrtrkaron. h.D., Brent Constantz, Ph.D., John Skedros’, M.D., R.D. Bloebaum”, Ph.D. Norian Corporation, Mountain View, CA 94043 and CORRELATION
*Division of Orthopedic Surgery, University of Utah Medical Center, Salt Lake City, UT 84148 The “Trajectorial theory” introduced by Wolf (1870; 1892) and later supported by others has predicted the relationship between bone remodelling and mechanical stresses. These findings
prompted us to determine the possible chemical and mineralogical changes in bone that happen due to mechanical stress. The calcaneus bone (of mule deer) is a relatively simple beam-like skeletal structure that functions as a lever arm which places its cranial(superior) aspect primarily in compressive stress and its caudal (inferior) aspect primarily in tensile stress. A total of twenty calcaneus bones were examined. The samples were tested for mineralogy using XRD and FTIR and for organic analysis using total proteins and amino acids assay. In addition, a new technique was used to assess the level of protein crosslinking. Highly significant differences were observed in the relative amounts of collagen cross-linking between the two bone sections: An average of 24% higher cross-linking of the superior portion was observed compared to the inferior portion. These results may bs interpreted as meaning that the collagen matrix of bone that is under compression becomes more cross-linked to provide greater mechanical rigidity.
661