Comparison of Trunk Strategy to Maintain Balance during the One-Leg Stance on a Medio-Lateral Ramp and an Anterior-Posterior Ramp

Purpose: This study examined two trunk strategies - medio-lateral ramp and anterior-posterior ram - and their effects on pelvis and trunk movements, providing basic material for safe ramp utilization. Methods: The present study included 20 asymptomatic males recruited from a local university. Participants were asked to stand with their feet shoulder-width apart. Their dorsal side faced the camera, and measurements were performed while standing in a neutral double stance, one leg stance, $15^{\circ}$ of medial and lateral ramp, and $15^{\circ}$ of anterior and posterior ramp. Participants were allowed to practice for 3 minutes, and each participant had a 30 seconds rest between the two ramp conditions. One-way repeated measures analysis of variance was used to determine the effects the ramp conditions on spinal alignment. In all analyses, p<0.05 was used to indicate statistical significance. Results: The trunk-inclination angle on the posterior ramp was significantly lower than that of the double stance position (p<0.05). The trunk imbalance angle was significantly higher on the medial ramp, than that on the double stance position (p<0.05). The pelvic position and pelvic torsion angles were significantly higher in the medial, lateral, and anterior ramp positions than that of the double stance position (p<0.05). The pelvic rotation angles on the medial, lateral, and anterior ramps were significantly lower than that of the double stance position (p<0.05). Conclusion: These findings suggest that when people are exposed to the same form of ramp for an extended period, posture modifications may be triggered.