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Impact characteristics of soccer balls varying in size and design
1042
Abstracts--International
Society of Biomechanics
XII Congress 1989
A CEI~ERALIZ%D TIIRORY OF A STRUCTIJRAL U:Ai,YSIS OF TEE GAIT XiXIECIiAXICS A.P.Kuzhekin, I.nT.Dobrov and B.S.Farber Central Research Institute of Prosthetics, 117071 BIoscow, VSSR. An integrated theory of structural couplings of the gait biomechanits has been suggested for the first time. The theory makes possible to perform a differential estimation of the walking stereotypes based on a total combination of their biomechanical and physiological charecteristics taken as a whole and to analyze purposive orientation of separate phases of a step as well.For this purpose formalization of the laws of of the structural couplings has been developed based on an automodel approach in relation of biomechanics of tha walking. The locomotions have been considered as an act directed to the translation of a human body in space and in time and defined by the three dominant factors: retionality of energetics, specificity of the environment end the need to take into consideration the limitations induced by the structural properties of a supporting-motor apparatus.
IMPACT CHARACTERISTICS OF SOCCER BALLS VARYING IN SIZE AND DESIGN. Charles W. Armstrong & Bruce Kwiatkowski, Division of Exercise Science, University of Toledo, Timothy A. Levendusky, Department of Physical Education, Southern Methodist University, Leon Kugler, Point Loma Nazarene College, The University of Toledo, Toledo, Ohio 43606, U.S.A. Fifty-eight soccer balls, varying in size (size 5, 4, 3) and design (outdoor, indoor, lightweight) were examined to determine the influence of these factors on specific characteristics of impact. Each was dropped repeatedly from a height of 18 meters onto a force platform. Impact data were sampled at 6 KHz and processed to provide measures of peak force, rise time, impact duration, and total impulse. A one-way ANOVA revealed that ball size and design significantly influenced selected impact characteristics. Of specific note, both peak force and total impulse increased as ball size increased. Rise time (adjusted for differences in peak force) was longest in the indoor balls and shortest in the 13 and lightweight balls. These results provide a basis for differentiating the effects of size and design on soccer ball impact, and may provide some insight into the mechanism of head injury in soccer.
REGULATION OF MUSCLE FORCE AND STIFFNESS DURING LONG JUMP TAKE OFF Heikki Kyrblainen, Janne Avela and Paavo V. Komi Department of Biology of Physical Activity, University of Jyvaskyla, SF-40100 JKL, Finland During the take-off a long jumper is subjected to high impact forces. In order to avoid dropping of the body center of gravity during impact the muscle stiffness in the takeoff leg must be as high as possible. In this study a subject performed two good (6.53 + 0.03 m) and two medium (5.20 + 0.18 m) long jumps over the force platform.-+11 jumps had the same maximum run up of 20 m. Each performance was filmed at 100 frames x s , and the film analysis was used to estimate the length changes of the triceps surae muscle during the take-off contact. Achilles tendon force (ATF) was recorded directly using the in-vivo technique, in which the buckle type transducer was implanted under the local anesthesia around the achilles tendon of the take-off lea. Surface EMGs were recorded telemetrically from the qastrocnemius, tibialis anterior and-vastus lateralis muscles. The results demonstrated great differences between good and medium jumps in Fz ground reaction forces (2873 N vs. 2191 Nl than in oeak ATF (2044 N vs. 1975 N). However. the rate of ATF development This was associated with very high peak stiffness was much greater in thegood jumps. coefficients in the good jumps (10.7) as compared to the medium jumps (6.8). During the impact phase the peak angular velocities both in the knee and ankle joints were higher in the good jumps. In addition the duration of the eccentric phase was shorter, but at the same time the IEMG of the gastrocnemius muscle was higher in the better jumps. The results suggest that increased EMG-during preactivation and eccentric (impact) phases causes increased tendomuscular stiffness, which in turn facilitates powerful use of the stretchshortening cycle in the long jump-take-off.
Abstracts--International
Society of Biomechanics
XII Congress 1989
A CEI~ERALIZ%D TIIRORY OF A STRUCTIJRAL U:Ai,YSIS OF TEE GAIT XiXIECIiAXICS A.P.Kuzhekin, I.nT.Dobrov and B.S.Farber Central Research Institute of Prosthetics, 117071 BIoscow, VSSR. An integrated theory of structural couplings of the gait biomechanits has been suggested for the first time. The theory makes possible to perform a differential estimation of the walking stereotypes based on a total combination of their biomechanical and physiological charecteristics taken as a whole and to analyze purposive orientation of separate phases of a step as well.For this purpose formalization of the laws of of the structural couplings has been developed based on an automodel approach in relation of biomechanics of tha walking. The locomotions have been considered as an act directed to the translation of a human body in space and in time and defined by the three dominant factors: retionality of energetics, specificity of the environment end the need to take into consideration the limitations induced by the structural properties of a supporting-motor apparatus.
IMPACT CHARACTERISTICS OF SOCCER BALLS VARYING IN SIZE AND DESIGN. Charles W. Armstrong & Bruce Kwiatkowski, Division of Exercise Science, University of Toledo, Timothy A. Levendusky, Department of Physical Education, Southern Methodist University, Leon Kugler, Point Loma Nazarene College, The University of Toledo, Toledo, Ohio 43606, U.S.A. Fifty-eight soccer balls, varying in size (size 5, 4, 3) and design (outdoor, indoor, lightweight) were examined to determine the influence of these factors on specific characteristics of impact. Each was dropped repeatedly from a height of 18 meters onto a force platform. Impact data were sampled at 6 KHz and processed to provide measures of peak force, rise time, impact duration, and total impulse. A one-way ANOVA revealed that ball size and design significantly influenced selected impact characteristics. Of specific note, both peak force and total impulse increased as ball size increased. Rise time (adjusted for differences in peak force) was longest in the indoor balls and shortest in the 13 and lightweight balls. These results provide a basis for differentiating the effects of size and design on soccer ball impact, and may provide some insight into the mechanism of head injury in soccer.
REGULATION OF MUSCLE FORCE AND STIFFNESS DURING LONG JUMP TAKE OFF Heikki Kyrblainen, Janne Avela and Paavo V. Komi Department of Biology of Physical Activity, University of Jyvaskyla, SF-40100 JKL, Finland During the take-off a long jumper is subjected to high impact forces. In order to avoid dropping of the body center of gravity during impact the muscle stiffness in the takeoff leg must be as high as possible. In this study a subject performed two good (6.53 + 0.03 m) and two medium (5.20 + 0.18 m) long jumps over the force platform.-+11 jumps had the same maximum run up of 20 m. Each performance was filmed at 100 frames x s , and the film analysis was used to estimate the length changes of the triceps surae muscle during the take-off contact. Achilles tendon force (ATF) was recorded directly using the in-vivo technique, in which the buckle type transducer was implanted under the local anesthesia around the achilles tendon of the take-off lea. Surface EMGs were recorded telemetrically from the qastrocnemius, tibialis anterior and-vastus lateralis muscles. The results demonstrated great differences between good and medium jumps in Fz ground reaction forces (2873 N vs. 2191 Nl than in oeak ATF (2044 N vs. 1975 N). However. the rate of ATF development This was associated with very high peak stiffness was much greater in thegood jumps. coefficients in the good jumps (10.7) as compared to the medium jumps (6.8). During the impact phase the peak angular velocities both in the knee and ankle joints were higher in the good jumps. In addition the duration of the eccentric phase was shorter, but at the same time the IEMG of the gastrocnemius muscle was higher in the better jumps. The results suggest that increased EMG-during preactivation and eccentric (impact) phases causes increased tendomuscular stiffness, which in turn facilitates powerful use of the stretchshortening cycle in the long jump-take-off.