Relationships between Stride Frequency, Stride Length, Step Length and Velocity with Asymmetric Gaits in the Thoroughbred Horse

The present study was to describe the relationships between stride frequency, stride length, step length and velocity in the upper submaximal velocity range in Thoroughbreds.Three Thoroughbred horses, aged two-year-old, in race training were used.Each horse performed six trials at six different velocities including near maximum velocity for each individual horse.Stride length and step length were measured from the hoof prints on the ground and stride frequency was measured from the acceleration curve upon hoof impact on the recording paper.As the mean variation coefficients for stride length and stride frequency were 2.1% and 1.6% respectively, it was considered that the gait characteristics of stride length and stride frequency exhibited good stability at canter and gallop in each individual horse.Both stride length and stride frequency almost linearly increased with increasing velocity.However, at higher velocities, stride length tended to show a decreased rate of increase, whereas stride frequency tended to indicate an increased rate of increase.Airborne and mid step lengths showed a greater increase with increasing velocity than hind and fore step lengths.Airborne step length showed a leveling off, whereas mid step length showed an increased rate of increase at higher velocities.It was considered that the leveling off in airborne step length resulted from the braking force to the forelimb growing bigger and the increased rate of increase in mid step length resulted from the propelling force to the hind limb growing bigger at higher velocities.