SURFACE ELECTROMYOGRAPHY OF ABDOMINAL AND SPINAL MUSCLES IN ADULT HORSERIDERS DURING RISING TROT

Abstract

The purpose of this study was to determine activation patterns of iliocostalis lumborum and rectus abdominis in horse riders during rising trot. Horse riders (n=10) of varying abilities (casual rider to Prix St George rider), aged from 20 – 57 were involved in the study. Electromyographic activity was recorded bilaterally from iliocostalis lumborum and rectus abdominis. In addition, movement at the lumbosacral joint was recorded using an electrogoniometer. The subjects were asked to walk and then perform rising trot on their horses. The electromyographic signals were full-wave rectifed and a moving filter was applied to the signal. Patterns of activation between sides and between muscles were determined. Coactivation of the right and left sides was present for all riders. The novice riders displayed coactivation of rectus abdominis and iliocostalis lumborum whereas the experienced riders had a phase shift between these two muscles. Rectus abdominis behaved as an agonist in the experienced rider, contracting as the rider made contact with the saddle on the outside diagonal. Controlled activation of the rectus abdominis is an important feature in the experienced rider. Training regimes for horse riders should incorporate specific exercising of the abdominal muscles.