OBJECTIVE: To assess the rider's movement during walking the horse in repeated therapeutic horse riding sessions and to determine the relationship between movements of the horse's back and the rider's trunk. METHOD: A total of 12 healthy females (age: 23.3+-2.8 years; height: 167.3+-4.2 cm; weight: 59.2+-5.3 kg) participated in 10 therapeutic horse riding sessions.
Two English Thoroughbreds with similar body constitution (aged 19 and 14 years) were used in the experiment. Nine markers were placed on the rider's body and the horse's back, and four video cameras with a 25 Hz frequency were used.
Col- lected data were processed with APAS software. RESULTS: The mediolateral displacements of C7, Th12, and L5 were gradually decreasing in each of the first three sessions.
Statistically significant differences (p<0.05) were found between individual sessions in the displacement of C7, Th12 and L5 in the mediolateral and vertical directions as well as in the shoulder and pelvic lateral tilt and rotation. These differences did not show any general tenden- cies regarding the riders' increasing experiences with riding.
The relationships between the displacement of C7, Th12, and L5 and the sacral tuber on the horse's back in the vertical direction were statistically significant (p <0.01) during all ses-sions. CONCLUSIONS: The displacement of C7, Th12 and L5 in the mediolateral direction decreased during riding sessions.
A significant relationship was found between the vertical movement of the horse's back and the rider's trunk. These relationships differed between the horses.