Equine locomotion; 1. The analysis of linear and temporal stride characteristics of trotting standardbreds.

The movements of the individual limbs of 30 clinically sound Standardbred trotters were studied using high-speed cinematography. At a speed of 12 metres per second (m/sec; 1:23.6 min/km) the mean stride length was 545 cm and the mean duration of the stride was 455 milliseconds (msecs). The stance phase in the forelimbs was 100 msecs and 177 msecs in the hindlimbs. This difference was due to a longer restraint period in the hindlimbs and resulted in slightly shorter swing phases for the hindlimbs. The variations in any particular horse for stride length and for the duration of stride, stance, swing and propulsion were very small (variation coefficient: approximately 2 per cent). For the restraint stage, however, the variation coefficient was around 5 per cent. The variations noted between different horses were generally 2 to 3 times greater than those recorded for the same horse. There was a close correlation between stride and swing phase duration, suggesting that the swing phase was the main contributor to the stride-time variations of different horses trotting at the same speed. The restraint and propulsion stages did not seem to play an important role in this respect for this group of animals.