In transverse gallop the leading feet (i.e. the second limb of each pair on the ground) of hind and forelimbs are ipsilateral. Therefore, we can distinguish a right-leading by a left-leading gallop.

When turning, a horse leads with its inside limbs. Consequently, during direction changes, right-hand bends are covered using right-leading gallop and vice-versa. Even if there are preferences for the leading foot on straights, probably due to individual asymmetries of the body, we also observe periodical lead changes. Potential reasons for those are: a) the interaction between the shoulder and the thoraco-pulmonar complex, which is maximum during the lead leg support, and b) musculo-skeletal stress induced by the gait asymmetry (the trunk sagittal plane deviated from the progression plane by 3ordm;, pers. obs.).

Also by considering that the lead change discontinuity on straights is expected to decrease gallop performance, we hypothesized that there should be a consistently "optimal" number of strides or distance between lead changes.

From the analysis of 84 horse-race videos of different tracks in Italy, we found that 48 ± 20 strides were covered between two successive lead changes on straights. As expected, race distance, the number of bends to be covered and, possibly, the 'rider-factor' influenced the number of changes. The predominant leading leg used on straightaways is significantly different from that employed during bends in both clockwise and counter-clockwise racetracks.