Effect of speed on stride parameters in racehorses at gallop in field conditions

Abstract

SUMMARY Stride duration, stance duration and protraction duration are key variables when describing the gaits of terrestrial animals. Together, they determine the duty factor (the fraction of the stride for which the limb maintains contact with the ground surface), from which the peak vertical force can be estimated. When an animal changes speed, these variables change at different proportions. Limited measurements of these variables and predictions of peak limb force have been undertaken for large mammals performing high-speed over-ground exercise. This study set out to make such measurements, employing a previously validated system consisting of limb-mounted accelerometers and a Global Positioning System data logger. Measurements were made on nine elite Thoroughbred racehorses during gallop locomotion over a range of speeds from 9 to 17 m s-1. No statistically significant differences were seen in any variables between the lead and non-lead limbs for either the fore or hind pairs of limbs. Mean stance durations of 131 and 77 ms in the forelimbs and 143 and 94 ms in the hindlimbs were recorded at speeds of 9 and 17 ms-1, respectively. Equivalent values for protraction duration were 364 and 342 (fore) and 355 and 326 ms (hind). Peak limb forces (from duty factor) at 17 ms-1 were 24.7 N kg-1 body weight (range 22.6 to 26.0 N kg-1 body weight) for the forelimbs and 15.3 N kg-1 (range 13.7-16.2 N kg-1 body weight) for the hindlimbs. The duration of the aerial phase of the stride (when no limbs are in contact with the ground) was independent of speed. Overlap time (when more than one leg is on the ground) dropped with speed and approached zero at maximum speed.

High speed galloping in the cheetah (Acinonyx jubatus) and the racing greyhound (Canis familiaris): spatio-temporal and kinetic characteristics

“…In contrast, an increase in mean stride frequency from 2.4 to 3.2Hz was observed in the cheetah. Across the whole dataset, maximum stride frequencies of 3.9Hz were used by both species; a maximum that far exceeds that used by other fast quadrupeds (Heglund and Taylor, 1988;Witte et al, 2006) and that previously observed for the cheetah (Hildebrand, 1961). For both species, a linear increase in stride length with speed was observed, and the cheetah used longer stride lengths than the greyhound, which can be explained by the cheetah's slightly longer limbs and back (Hudson et al, 2011a;Hudson et al, 2011b).…”

“…During a stride an animal must produce a vertical impulse that is equal to the product of its body weight and stride time in order to support its body weight. The impulses required to do this must be generated during stance, and therefore, because of decreases in contact time and duty factor with increasing speed (observed in several animals) (Hoyt and Taylor, 1981;Kram and Taylor, 1990;Usherwood and Wilson, 2005;Weyand et al, 2000;Witte et al, 2006), greater peak ground reaction forces (GRFs) must be resisted by the limbs to support the body weight of the animal. An animal may therefore encounter a speed where its limbs cannot resist a higher peak GRF (a force limit) perhaps due to the contraction properties or architecture of its muscles, or the safety limits of the skeletal elements of the limb may be approached.…”

An exploratory clustering approach for extracting stride parameters from tracking collars on free ranging wild animals

“…Changes in stride frequency and length with speed are key parameters in human locomotion research (Maculewicz et al, 2016;Muro-de-la-Herran et al, 2014) and are routinely used in quadruped locomotion research (Heglund and Taylor, 1988;Jayne and Irschick, 2000;Smith et al, 2015;Sue et al, 2011;Witte et al, 2006). Measurement of these parameters enables the locomotor strategy used by an animal to attain a particular speed to be determined.…”

An Investigation of Humeral Stress Fractures in Racing Thoroughbreds using a 3D Finite Element Model in Conjunction with a Bone Remodeling Algorithm

“…Slow gallop and fast gallop joint contact forces were estimated based on peak vertical ground reaction forces, which were based on accelerometer data from a previous study (Witte et al, 2006). In this model, a slow gallop was defined as a velocity of 10m/s at 2.8 times walking force with a peak vertical force of 1.8 times body weight.…”

“…The slow gallop (days 1-5) distance of 0.7 is maintained throughout the entire program except when there is a period of layup in which the horse does not complete a slow gallop workout. Slow and fast gallop speeds of 10m/s and 17m/s were based on stride rates of 2.0 strides/second and 2.2 strides/second, respectively (Witte et al, 2006). After initial training, there is 8 weeks of layup in which the horse only undergoes 0.5 hours of walking and standing each day.…”