Rosette strain gauges were attached to the midshaft of the radius and tibia of two horses and two dogs, which ran on a treadmill through their entire range of speed and gait. The relative magnitudes of the principal strains on the opposite cortices of each bone remained constant through the stance phase of the stride, and their orientation varied by a maximum of only 14 degrees through the entire speed range. The maximum strain rate increased linearly with speed, but the peak strain magnitude was also dependent upon the gait used, increasing incrementally by up to 59% at the transition from walk to trot, and dropping by 42% from a trot to a canter. Force transducers attached to the shoes of one horse indicated similar changes in ground load. The peak strains induced during vigorous activity are remarkably uniform in a wide range of animals. This suggests that the skeleton is scaled to provide constant safety margins between peak functional strains and those at which yield and ultimate failure occur.

/pdf/limb-mechanics-as-a-function-of-speed-and-gait-a-study-of-5e9cu50myy.pdf

How mammals run

Limb mechanics as a function of speed and gait: a study of functional strains in the radius and tibia of horse and dog

It is argued that the traditional psychological construal of the distinction between central ("open loop") and peripheral ("closed loop") neural processes is no longer tenable. A review of the relevant psychobiological research on the control of movement shows that both the central-peripheral dichotomy and the distinction between sensory and motor systems derived from that dichotomy are incompatible with what is known about the processes underlying action. Based on experimental and comparative data, a new theory of action is proposed. The basic concept of this new theory is the action system: Unlike motor systems, action systems involve sensory as well as motor processes; action systems are not organized into response hierarchies, but rather in coalitional structures of adjustable movements and postures. The phylogeny of action systems is discussed, and the eight most important action systems are distinguished in terms of their evolved distinctive functions. The difficulties of developing a taxonomy of actions for functionally specific types of behavior made up of that can be controlled is resolved by showing how kinds of action are differentiated by the kinds of affordances their components help to realize.

An outline of a theory of action systems.

The available data on maximal running speeds of mammals are presented, and the relationship between speed and body mass is considered. For all mammals (n= 106), maximal running speed scales as (body mass)0–17; however, the largest mammals are not the fastest, and an optimal size with regards to running ability is suggested ( 119 kg). Maximal running speeds are, on the average, somewhat more than twice maximal aerobic speeds.

Within the Artiodactyla, Carnivora or Rodentia, maximal running speed is mass independent, in agreement with theoretical expectations for geometrically similar animals (Thompson, 1917; Hill, 1950). McMahon's (1975b) model for elastic similarity is therefore not supported by the available data on maximal running speeds, and there appears to be no necessary correspondence between scaling of limb bone proportions and running ability.

http://www.biology.ucr.edu/people/faculty/Garland/Garl1983_JZL.pdf

The relation between maximal running speed and body mass in terrestrial mammals

In this paper, I assess the correspondence between locomotor function (climbing, digging, and running) and skeletal morphology in living carnivores. Published behavioral observations are used to assign fifty-three extant carnivore species to four broad locomotor categories: arboreal, scansorial, terrestrial, and semi-fossorial. Body weight and measurements of claw shape, relative size of fore and hind claws, olecranon size and orientation, astragalar shape, and manus and hindlimb proportions are presented for each species. The correspondence between locomotor type and morphologic indices is examined with bivariate and multivariate (discriminant function) analyses. Results demonstrate that osteological indices are good predictors of locomotor behavior among extant carnivores. Arboreal and scansorial carnivores exhibit relatively more curved claws, longer proximal phalanges, and shorter metatarsals than do terrestrial taxa; semi-fossorial carnivores differ from other locomotor types in having relat...

How mammals run

Citations

Limb mechanics as a function of speed and gait: a study of functional strains in the radius and tibia of horse and dog

An outline of a theory of action systems.

The relation between maximal running speed and body mass in terrestrial mammals

Skeletal indicators of locomotor behavior in living and extinct carnivores

Support polygons and symmetrical gaits in mammals

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