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Comparison of mechanical energy expenditure of anthropomorphic locomotion machine and human
Abstracts-InternationalSocietyof BiomechanicsXIV Congress1993
645
THE KINETICS AND KINEMATICS OF POWERFUL UPPER BODY MOVEMENTS: THE EFFECT OF LOAD Robert U. Newton and Greg J. Wilson Centre for Human Movement Science and Sport Management University of New England, Northern Rivers, Lisrnore, NSW 2480, Australia There has been considerable controversy over the use of light (3050% MVC) versus heavy (80-95% MVC) loads for the development of muscular power. This study aimed to compare the muscular force, EMG, power output and bar velocity during dynamic bench throw movements over a range of relative loads. Force was measured using a Kistler force plate with a specially designed bench attached. The Plyometric Power System was used to record displacement time data for subsequent calculation of velocity, acceleration and instantaneous power output. Both stretch shorten cycle (SSC) and concentric only (CO) throws were attempted at loads of 15, 30, 45, 60, 75, 90 and 100% of 1 repetition maximum load. Force output of the muscle was greater for heavy as compared to lighter relative loads (~~0.05). However, force output when throwing the lighter loads was 2-5 times the actual weight thrown due to the acceleration component. The typical concentric force velocity relationship was evident during the dynamic, multijoint upper body movement used in this study. Mechanical power measured as the average over the entire concentric movement was maximised at the 30% and 45% 1RM loads. Peak instantaneous power was produced at the 15% 1 RM load. There was no significant effect of load thrown on EMG activity indicating that during powerful movements even with a light load there is considerable activation of the muscles involved. The SSC did not enhance performance in terms of peak velocity attained or throw height. It would seem that although the SSC contributes to the start of the concentric movement, its effect is diminished towards the release point. The study highlighted a need to further assess the adaptations to power training using accelerative movements especially with regard to the optimal load for the development of useable power for sport and work performance.
STRESS AND STRAIN IN THE FLIGHT MUSCLES AS CONSTRAINTS FLYING ANIMALS
ON THE EVOLUTION
OF
C.J. Pennycuick Departmentof Zoology, University of Bristol, Woodland Road, Bristol BS8 lUG, Great Britain. The minimum mechanicalpower required for a bird to fly horizontally can be calculated, if the bird’s body mass, wing span and wing area are known, plus the strength of gravity and the air density. The wing beat frequency can also be estimated, and hencethe work done by the muscles in each contraction. From this, the product of stressand strain during shorteningcan be estimated.This calculation was carried out for 150 speciesof living birds, using only new data, collected by standard methods,by observersknown to the author. The calculated specific work for the myofibrils increases with about the 0.26 power of the body mass,the largest speciesrequiring about 57 J/kg to account for level flight. This could be accomplished,for example,if a stressof 240 kPa were combined with a strain of 0.25. Extrapolation of the data to simulate the giant Miocene bird Argentavis magnificens suggests that this creature could not have flown horizontally, unless gravity were weaker at that time. The aerobic scope (ratio of minimum power for horizontal flight to basal metabolic rate) was calculated from the same data, and found to increasewith the 0.38 power of the body mass. Values approaching 50 would be required in the largest speciesknown to be capableof prolonged horizontal flight during migration, The effect of thesetrends is that the potential diversity of flying animals is high in the range of body mass lo-100 g, reduced at 1 kg, down to a few speciesat 10 kg, and zero above about 14 kg.
COMPARISON OF MECHANICAL ENERGY EXPENDITURE OF ANTHROPOMORPHIC LOCOMOTION MACHINE AND HUMAN B.I. Prilutsky BiomechanicsLaboratory, Central Institute of Physical Culture, Moscow 105483,Russia. Preserktaddress:Human PerformanceLaboratory, The University of Calgary, Calgary, Canada. The aim of this study was to compare mechanicalenergyexpenditure(MEE) of the lower extremities of a human, with those of an anthropomorphiclocomotion machineusing a theoretical analysis.Sourcesof mechanical energy producing movement of the human lower extremity model were presentedby eight muscles,three of which were two-joint musclea.Sourcesof mechanicalenergyproducing movement of the machine model were joint momenta.For convenienceof comparisonof the MEE of both models, the model of the anthropomorphicmachine was changedby ‘identical transformations’.The mechanicalenergy sourcesof the machine extremity (the joint momenta)were substituted for muscle forces of the human model in such a way that total MEE of the sources of the machine extremity model remained unchanged.The transformedmodel differed from the model of the human extremity by absenceof two-joint muscles,which have been substitutedby pairs of one-joint muscleshaving the same action at correspondingjoints. The above transformationsensuredthe samemomentaand powers at the joints for a given movement of the models. The transformationsdid not changetotal MEE of the machine extremity energy sourcesif antagonistic muscleswere not active. It was shown that the model of the human extremity (with two-joint muscles) could spendless mechanicalenergythan that of the model of the anthropomorphicmachine
645
THE KINETICS AND KINEMATICS OF POWERFUL UPPER BODY MOVEMENTS: THE EFFECT OF LOAD Robert U. Newton and Greg J. Wilson Centre for Human Movement Science and Sport Management University of New England, Northern Rivers, Lisrnore, NSW 2480, Australia There has been considerable controversy over the use of light (3050% MVC) versus heavy (80-95% MVC) loads for the development of muscular power. This study aimed to compare the muscular force, EMG, power output and bar velocity during dynamic bench throw movements over a range of relative loads. Force was measured using a Kistler force plate with a specially designed bench attached. The Plyometric Power System was used to record displacement time data for subsequent calculation of velocity, acceleration and instantaneous power output. Both stretch shorten cycle (SSC) and concentric only (CO) throws were attempted at loads of 15, 30, 45, 60, 75, 90 and 100% of 1 repetition maximum load. Force output of the muscle was greater for heavy as compared to lighter relative loads (~~0.05). However, force output when throwing the lighter loads was 2-5 times the actual weight thrown due to the acceleration component. The typical concentric force velocity relationship was evident during the dynamic, multijoint upper body movement used in this study. Mechanical power measured as the average over the entire concentric movement was maximised at the 30% and 45% 1RM loads. Peak instantaneous power was produced at the 15% 1 RM load. There was no significant effect of load thrown on EMG activity indicating that during powerful movements even with a light load there is considerable activation of the muscles involved. The SSC did not enhance performance in terms of peak velocity attained or throw height. It would seem that although the SSC contributes to the start of the concentric movement, its effect is diminished towards the release point. The study highlighted a need to further assess the adaptations to power training using accelerative movements especially with regard to the optimal load for the development of useable power for sport and work performance.
STRESS AND STRAIN IN THE FLIGHT MUSCLES AS CONSTRAINTS FLYING ANIMALS
ON THE EVOLUTION
OF
C.J. Pennycuick Departmentof Zoology, University of Bristol, Woodland Road, Bristol BS8 lUG, Great Britain. The minimum mechanicalpower required for a bird to fly horizontally can be calculated, if the bird’s body mass, wing span and wing area are known, plus the strength of gravity and the air density. The wing beat frequency can also be estimated, and hencethe work done by the muscles in each contraction. From this, the product of stressand strain during shorteningcan be estimated.This calculation was carried out for 150 speciesof living birds, using only new data, collected by standard methods,by observersknown to the author. The calculated specific work for the myofibrils increases with about the 0.26 power of the body mass,the largest speciesrequiring about 57 J/kg to account for level flight. This could be accomplished,for example,if a stressof 240 kPa were combined with a strain of 0.25. Extrapolation of the data to simulate the giant Miocene bird Argentavis magnificens suggests that this creature could not have flown horizontally, unless gravity were weaker at that time. The aerobic scope (ratio of minimum power for horizontal flight to basal metabolic rate) was calculated from the same data, and found to increasewith the 0.38 power of the body mass. Values approaching 50 would be required in the largest speciesknown to be capableof prolonged horizontal flight during migration, The effect of thesetrends is that the potential diversity of flying animals is high in the range of body mass lo-100 g, reduced at 1 kg, down to a few speciesat 10 kg, and zero above about 14 kg.
COMPARISON OF MECHANICAL ENERGY EXPENDITURE OF ANTHROPOMORPHIC LOCOMOTION MACHINE AND HUMAN B.I. Prilutsky BiomechanicsLaboratory, Central Institute of Physical Culture, Moscow 105483,Russia. Preserktaddress:Human PerformanceLaboratory, The University of Calgary, Calgary, Canada. The aim of this study was to compare mechanicalenergyexpenditure(MEE) of the lower extremities of a human, with those of an anthropomorphiclocomotion machineusing a theoretical analysis.Sourcesof mechanical energy producing movement of the human lower extremity model were presentedby eight muscles,three of which were two-joint musclea.Sourcesof mechanicalenergyproducing movement of the machine model were joint momenta.For convenienceof comparisonof the MEE of both models, the model of the anthropomorphicmachine was changedby ‘identical transformations’.The mechanicalenergy sourcesof the machine extremity (the joint momenta)were substituted for muscle forces of the human model in such a way that total MEE of the sources of the machine extremity model remained unchanged.The transformedmodel differed from the model of the human extremity by absenceof two-joint muscles,which have been substitutedby pairs of one-joint muscleshaving the same action at correspondingjoints. The above transformationsensuredthe samemomentaand powers at the joints for a given movement of the models. The transformationsdid not changetotal MEE of the machine extremity energy sourcesif antagonistic muscleswere not active. It was shown that the model of the human extremity (with two-joint muscles) could spendless mechanicalenergythan that of the model of the anthropomorphicmachine