Energetics and mechanics of swing phase during terrestrial locomotion

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" Energetics and mechanics of swing phase during terrestrial locomotion "
Frank E. Nelson T. J. Roberts

Document Type	:	Latin Dissertation
Language of Document	:	English
Record Number	:	53348
Doc. No	:	TL23302
Call number	:	‭3241575‬
Main Entry	:	Frank E. Nelson
Title & Author	:	Energetics and mechanics of swing phase during terrestrial locomotion\ Frank E. Nelson
College	:	Oregon State University
Date	:	2006
Degree	:	Ph.D.
student score	:	2006
Page No	:	156
Abstract	:	Previous attempts to understand the factors affecting the energetic cost of locomotion have found a direct link between the energetic cost and the mechanical work done during periods when the limb is in contact with the ground. However, when the limb is not in contact with the ground during the swing phase, this link between mechanical work and energetic cost disappears. I examined the mechanics of swing to explore the possibility of passive mechanisms allowing for the performance of mechanical work with little to no energetic cost during swing. Previous studies have ruled out the possibility of a pendulum exchange of gravitational potential and kinetic energy during human locomotion because the swing frequencies are too high. I added the accelerations of the body during stance to the swinging lower limb to determine if the frequency where the pendulum-like exchange of energy occurs could be increased. These accelerations increased the frequency where energy exchange occurs and thereby reduced the work required to swing the human lower limb. The pendulum-like exchange of energy reduces the work required for swing, but some work is still required. To explore how the remaining work for swing was produced I examined two muscles potentially involved in producing an extension moment about the intertarsal joint of turkeys during swing. The only muscle providing force for intertarsal joint extension during swing was the lateral head of the gastrocnemius (LG). A comparison of the in situ length-tension curve and in vivo operating lengths during swing revealed the LG operated at long lengths on the descending limb of the length tension curve during swing. Finally I characterized the force-velocity curve of the LG and found the muscle to have mechanical properties within the range previously determined for other vertebrates. In conclusion, I determined a passive mechanism which could reduce the required mechanical work of swing and thereby explain part of the apparent lack of a link between mechanical work and energetic cost of swing. In addition, results from these studies suggest the remaining work necessary for swing may be provided by active contraction of muscle.
Subject	:	Biological sciences; Energetics; Locomotion; Skeletal muscle; Swing; Anatomy physiology; Animals; Biophysics; 0786:Biophysics; 0433:Animals; 0433:Anatomy physiology
Added Entry	:	T. J. Roberts
Added Entry	:	Oregon State University