Gallop velocity and limb contact variables of quarter horses

High-speed cinematography was used to examine the relationship between velocity and linear and temporal ground contact variables of the equine transverse gallop gait. The stride characteristics of four Quarter horse fillies were used as a model. Horses were approximately thirty months of age and had been raised and trained similarly. Horses were filmed by two cameras simultaneously (243 frames/second) while galloping under the standardized conditions of a specially constructed 1.5m-wide track. Horses were all ridden with the same saddle and bridle by one person. Kinematic variables determined for sixty-two strides included stride length, step lengths and stride frequency as well as contact and non-contact periods of single limbs and combinations of limbs. Galloping velocity (10.0 to 15.0 m/sec) was strongly influenced by stride frequency (2.16 to 3.04 sec⁻¹) and to a lesser extent by stride length (4.41 to 5.56 m). Stride length and stride frequency were independent. Variations in velocity were not associated with any detectable variations in absolute or relative distances between successive limb impacts. Increases in stride length at constant stride frequency were accomplished by increasing the distance between fore limb impacts and also the distance between fore leading limb impact and the subsequent hind trailing limb impact. Decreases in stride duration with increased galloping velocity occurred at the expense of hind trailing limb unipedal contact, fore leading limb unipedal contact and the airborne phase duration.