- Email: [email protected]
Strenuous exercise effects on mechanical properties and geometry of weightbearing vs nonweightbearing mature bones
Abstracts--International Society of BiomechanicsXII Congress1989
1091
COMPARISON OF VOLUNTARY AND OPTI= REGIMENS OF CYCLIC MOVEMENTSIN PEOPLE OF DIFFERENT AGE Utkin
V-L., Zaitseva Institute of
V-V., Sylakova E.V. (All-Union Research Physical Culture, Moscow, USSR)
among the most common criteria of Economy and performance are human motions. The question arises what is the optimality of difference between optimal and voluntary regimens of cyclic chosen by people of different age and physical movements, fitness. Results show that during even walking and running healthy adults voluntarily choose the most economic speed of significantly higher speed. In locomotions. Children choose voluntary chosen walking patients with ischemic heart disease is below energetically optimal. Voluntary dynamics of speed mechanical power differs in sportsmen and untrained subjects. choose almost constant power, and sportsmen choose Untrained Authors suggest to call the most productive regimen "all-out". this law as a "principle of maximal performance".
STRENUOUS EXERCISE EFFECTS ON MECHANICAL PROPERTIES AND GEOMETRY OF WEIGHTBEARING VS NONWEIGHTBEARING MATURE BONES Arthur C. Vailas, Ronald F. Zernicke*, Barbara J. Loitz*, Kelly McCranie*, Daniel Martinez Biodynamics Laboratory, 2000 Observatory Dr., Univ. Of Wisconsin, Madison, WI 53706 USA *Department of Kinesiology, UCLA, Los Angeles, CA 90024-1568 USA To examine the potential influencesof mechanicalloading and systemicfactors in bone remodeling, we comparedchangesinmechanicalpropertiesand geometryforthetarsometamrsus(TMT)andradius(RAD) between two groups of roosters: controls (n = 6) that receivedno exerciseand experimental animals (n = 5) that ran on a motorized treadmill 1 h/day, 5 d/wk for 9 wk at 80 - 85% VozmaX.Bones were loaded to failure in three-point bending. Middiaphysial crosssectionswere cut from contralateralbones to determine crosssectional geometry. Weightbearing and nonweightbearing bonesresponded differently to strenuousrunning. structural properties significantly increasedin TMT without changing geometry, while RADsignificantly increasedgeometry with no changesin structuralproperties. Cortical cross-sectionalarea increased27% in therunnerRADcomparedtocontrols;~corticalcross-sectionalareasdifferedlessthan1%betweenthe groups. Maximum load for runner TMT exceededcontrols by 62%, while runner RAD showed a 30% greater maximum load compared to controls. Resultssuggestedthat weightbearing and nonweightbearing bones respondeddifferently to strenuousexercise. Differences may reflect differing remodeling rates, with weightbearing bonesproducing and mineralizing new matrix faster than nonweightbeting bones. If loadbearingroles of the radius did not differ between exerciseand control animals,then remodeling in the nonweightbearing bones may reflect a generalizedsystemicresponseto strenuousexercise. Supportedby the Department of the Navy N66001-87-CO285
A METHOD OF MEASURING TRANSLATIONAL AND ROTATIONAL TRACTION CHARACTERISTICS OF FOOTWEAR Gordon A. Valiant NIKE Sport Research Lab, 9000 SW Nimbus Dr., Beaverton, OR 97005, USA. A device was developed to measure both the translational and rotational traction characteristics possessed by shoe outsoles. It incorporates a force measuring platform to which many different test surfaces can be fastened. High normal loads are achieved by stacking weights on a shaft pinned within the shoe. In the translation test, a shoe is pushed or pulled along the surface by the piston of an air cylinder. Sliding velocities are adjusted to speeds approaching footstrike velocities. The orientation of the shoe outsole with respect to the pulling force is variable. Kinetic coefficients, which are limited to the anterior outsole, are specified as a range. Less reliable measures of mean static coefficients are available. In addition to translation, the shoe can be rotated about a vertical axis through the medial metatarsal heads by a pressurized rotary actuator. The magnitude of the mean peak moment resisting rotation is analogous to a peak friction force developed during translation. It has been observed that materials used in current day footwear outsoles do not obey the classical Coulomb friction relations. Thus, in addition to comparing the friction characteristics of outsoles at loads and velocities that are equivalent to those occurring during activities for which each outsole was designed, the device is also useful for studying the physics of friction of these viscoelastic materials.
1091
COMPARISON OF VOLUNTARY AND OPTI= REGIMENS OF CYCLIC MOVEMENTSIN PEOPLE OF DIFFERENT AGE Utkin
V-L., Zaitseva Institute of
V-V., Sylakova E.V. (All-Union Research Physical Culture, Moscow, USSR)
among the most common criteria of Economy and performance are human motions. The question arises what is the optimality of difference between optimal and voluntary regimens of cyclic chosen by people of different age and physical movements, fitness. Results show that during even walking and running healthy adults voluntarily choose the most economic speed of significantly higher speed. In locomotions. Children choose voluntary chosen walking patients with ischemic heart disease is below energetically optimal. Voluntary dynamics of speed mechanical power differs in sportsmen and untrained subjects. choose almost constant power, and sportsmen choose Untrained Authors suggest to call the most productive regimen "all-out". this law as a "principle of maximal performance".
STRENUOUS EXERCISE EFFECTS ON MECHANICAL PROPERTIES AND GEOMETRY OF WEIGHTBEARING VS NONWEIGHTBEARING MATURE BONES Arthur C. Vailas, Ronald F. Zernicke*, Barbara J. Loitz*, Kelly McCranie*, Daniel Martinez Biodynamics Laboratory, 2000 Observatory Dr., Univ. Of Wisconsin, Madison, WI 53706 USA *Department of Kinesiology, UCLA, Los Angeles, CA 90024-1568 USA To examine the potential influencesof mechanicalloading and systemicfactors in bone remodeling, we comparedchangesinmechanicalpropertiesand geometryforthetarsometamrsus(TMT)andradius(RAD) between two groups of roosters: controls (n = 6) that receivedno exerciseand experimental animals (n = 5) that ran on a motorized treadmill 1 h/day, 5 d/wk for 9 wk at 80 - 85% VozmaX.Bones were loaded to failure in three-point bending. Middiaphysial crosssectionswere cut from contralateralbones to determine crosssectional geometry. Weightbearing and nonweightbearing bonesresponded differently to strenuousrunning. structural properties significantly increasedin TMT without changing geometry, while RADsignificantly increasedgeometry with no changesin structuralproperties. Cortical cross-sectionalarea increased27% in therunnerRADcomparedtocontrols;~corticalcross-sectionalareasdifferedlessthan1%betweenthe groups. Maximum load for runner TMT exceededcontrols by 62%, while runner RAD showed a 30% greater maximum load compared to controls. Resultssuggestedthat weightbearing and nonweightbearing bones respondeddifferently to strenuousexercise. Differences may reflect differing remodeling rates, with weightbearing bonesproducing and mineralizing new matrix faster than nonweightbeting bones. If loadbearingroles of the radius did not differ between exerciseand control animals,then remodeling in the nonweightbearing bones may reflect a generalizedsystemicresponseto strenuousexercise. Supportedby the Department of the Navy N66001-87-CO285
A METHOD OF MEASURING TRANSLATIONAL AND ROTATIONAL TRACTION CHARACTERISTICS OF FOOTWEAR Gordon A. Valiant NIKE Sport Research Lab, 9000 SW Nimbus Dr., Beaverton, OR 97005, USA. A device was developed to measure both the translational and rotational traction characteristics possessed by shoe outsoles. It incorporates a force measuring platform to which many different test surfaces can be fastened. High normal loads are achieved by stacking weights on a shaft pinned within the shoe. In the translation test, a shoe is pushed or pulled along the surface by the piston of an air cylinder. Sliding velocities are adjusted to speeds approaching footstrike velocities. The orientation of the shoe outsole with respect to the pulling force is variable. Kinetic coefficients, which are limited to the anterior outsole, are specified as a range. Less reliable measures of mean static coefficients are available. In addition to translation, the shoe can be rotated about a vertical axis through the medial metatarsal heads by a pressurized rotary actuator. The magnitude of the mean peak moment resisting rotation is analogous to a peak friction force developed during translation. It has been observed that materials used in current day footwear outsoles do not obey the classical Coulomb friction relations. Thus, in addition to comparing the friction characteristics of outsoles at loads and velocities that are equivalent to those occurring during activities for which each outsole was designed, the device is also useful for studying the physics of friction of these viscoelastic materials.