The Rat Gallope Analysis - curious topic
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Advanced Search SUMMARY Understanding how animals actually use their muscles during locomotion The Rat Gallope Analysis an important goal in the fields of locomotor physiology and biomechanics. Active muscles in vivo can shorten, lengthen or remain isometric, and their mechanical performance depends on the relative magnitude and timing of these patterns of fascicle strain and activation. It has recently been suggested that terrestrial animals may conserve metabolic energy during locomotion by minimizing limb extensor muscle strain during click here, when the muscle is active, facilitating more economical force generation and elastic energy recovery from limb muscle—tendon units.
Because previous work has tended to focus on the mechanical behavior of ankle extensors The Rat Gallope Analysis animal movements, the actions of more proximal limb muscles are less well understood. To explore further the hypothesis of force economy and isometric behavior of limb muscles during terrestrial locomotion, we measured patterns of electromyographic EMG activity and fascicle strain using sonomicrometry in Anallysis of the largest muscles of the rat hindlimb, the biceps femoris a hip extensor and vastus lateralis a knee extensor during walking, trotting and galloping. Our results show that the biceps and vastus exhibit largely overlapping bursts of electrical activity during the stance phase of each step cycle in all gaits. During walking and trotting, this activity typically commences shortly before the hindlimb touches the ground, but during galloping the onset of activity depends on whether the limb aRt trailing first limb down or leading second limb downparticularly in the vastus.
Biography of Stefano D'Orazio (excerpt)
In both muscles, EMG activity typically ceases approximately two-thirds of the way through the stance phase. In contrast to the minimal strain predicted by the force economy hypothesis, our results suggest that proximal limb muscles in rats operate over substantial length ranges The Rat Gallope Analysis stance over various speeds and gaits and exhibit complex and changing activation and strain regimes, exemplifying the variable mechanical roles that muscles can play, even during level, steady-speed locomotion.
Keywords: terrestriallocomotiongaitmuscleThe Rat Gallope AnalysiselectromyographysonomicrometryratRattus norvegicusbiceps femoris Introduction Muscles provide the forces and mechanical work necessary for moving animals through their environments over a range of speeds. Muscles of animals that interact with fluids to generate propulsion such as fish and birds have been shown to undergo relatively high levels of active strain and to generate substantial amounts of work and power during locomotion Altringham and Article source, ; Biewener et al. In contrast, work by Taylor and colleagues summarized in Taylor, suggests that, during terrestrial locomotion, the limb muscles of cursorial animals probably contract with small length excursions, doing little mechanical work but generating high levels of force.
Specifically, the ankle extensors of wallabies and turkeys undergo very low levels of muscle strain while generating high levels of force during the stance phase of steady, level locomotion.
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By minimizing fascicle strain and, hence, the mechanical work generated by muscles within the limb, Gallooe forces can remain high while the energetic cost of producing these forces can be reduced, increasing the performance Weyand et al. In addition, elastic energy stored in and released from tendons can offset much of the mechanical work that might otherwise be required by limb muscles during level, constant-speed running Alexander, ; The Rat Gallope Analysis et al. Therefore, if the mechanics of terrestrial locomotion allows limb muscles to operate generally with low strains when generating force during stance, animals may conserve metabolic energy expenditure.
However, because turkeys and wallabies constitute such a small subset of terrestrial vertebrates, and ankle extensors are distal muscles, and thus provide a limited sampling of the muscle—tendon systems within the whole limb, it remains important to investigate how widespread in vivo isometric contractile behavior actually is in the limb muscles of terrestrial animals.
Are wallabies and turkeys in some ways unique or do the distal hindlimb muscles of a wide variety of bipeds and quadrupeds also operate under largely isometric conditions during locomotion?
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Work by Walmsley et al. Walmsley et al. Whiting et al. Gregor et al. Prilutsky et al. Furthermore, in some of these studies, it was The Rat Gallope Analysis that muscle length excursions increased with locomotor speed, suggesting that speed or gait may also influence patterns of limb muscle strain during locomotion. In contrast to the relatively large The Rat Gallope Analysis of work that exists concerning in vitro and in vivo functional characteristics of various ankle click in a variety of animals, much less is known about functional aspects of more proximal muscles acting at the knee and hip.
Architecturally, muscles acting at the hip and knee tend to have longer fibers, lower pennation angles and higher muscle-to-tendon length ratios. Do these proximal-to-distal differences in muscle architecture underlie differences in strain patterns, such that limb muscles acting more proximally tend to undergo greater length changes than those acting more distally?
Given the crouched posture and increased limb compliance of small animals, might their limb muscles be expected to undergo greater length excursions than homologous muscles in large animals with more upright postures and click at this page limbs? The use of sonomicrometry for transducing muscle length changes in vivo during locomotion has now been applied successfully in a wide variety of animals Biewener et al.
In the present study, we use electromyography and sonomicrometry to measure directly patterns of activity and length change in two thigh muscles of the rat Rattus norvegicus over a broad range of speeds. We have undertaken this study with several goals in mind.
Introduction
First, we seek to test whether more proximally located muscles Th with higher strain levels during the stance phase than those previously measured in the more distal ankle extensors of wallabies and turkeys. Second, we want to test whether patterns of muscle strain during stance differ among speeds and gaits.
Specifically, do muscles exhibit greater degrees of strain as speed increases and as animals change gaits?]
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