Male vs. Female Horse Riders: Differences in Musculoskeletal Response to the Force Generated by a Horse at the Trot

Abstract

Anatomic differences in the bony pelvis and lumbar spine of male and female riders affect their riding postures. We have previously shown that the vertical force from the horse is directed toward the bodies of the lumbar vertebrae and intervertebral discs in males, but toward the zygapophyses and pedicles, an area less well-suited for force distribution, in females. The purpose of this study was to detail more specifically the forces generated by the muscles of a male and female rider in response to the force from the horse. Analysis of the classical riding posture in two phases (P1, P2) of the trot revealed: (1) In P1 of the trot, the torque from the horse affects the thorax, but not hip, of the female. It affects both in the male, who thus recruits the longissimus thoracis muscle for counterbalance. (2) In P1 of the trot, the psoas muscle is more vertically-oriented in the female, and thereby less capable than that of the male in creating forward movement of the lumbar spine. (3) The male generates relatively larger muscle forces in response to the same force from the horse in both phases, but in P1 the female iliacus muscle generates a force almost as large as that of the male, demonstrating its relative importance in the female. A better understanding of the functional consequences of such sexual dimorphisms allows riders to adapt their techniques to increase their effectiveness and decrease the potential for discomfort and injury.