The biomechanical construction of the horse’s body and activity patterns of three important muscles of the trunk in the walk, trot and canter.

The research examines the biomechanical activity of the horse’s trunk while walking, trotting, and cantering, focusing specifically on three trunk muscles. Surface electromyography (EMG) was used to test activity pattern predictions which were made using a theoretical analysis of trunk biomechanics.

Research Methodology

• The study involved five horses that were examined both with and without a rider to determine the patterns of muscle activity when the horses walk, trot, and canter.
• Activity of trunk muscles was measured using surface electromyography (EMG), a tool that records muscle movement and activity.
• An accelerometer was used to synchronize footfall with the EMG data, allowing for correlation of movement with muscle activity.
• The researchers averaged data from ten consecutive activity cycles and compared these findings utilizing statistical methods.
• The start and stop times of muscle activities were identified within 5-10 undisturbed EMG plots. The averages and standard deviations of these times were then calculated.

Key Findings

• Within the walk cycle, activity within the trunk muscles was found to be minimal.
• Increased activity was observed in the rectus muscle (m.rectus) during three-limb support – primarily observed during movement when horses’ mass is propelled upwards at twice the gravitational acceleration.
• In phases of trot and canter where torsional and bending moments are greatest, the external oblique muscle (m.obl.externus) is most active, mainly on one side, with the forces being balanced on the other side by the internal oblique muscle (m.obl.internus).
• The longissimus dorsi muscle (m.longissimus dorsi) was observed to stabilize the vertebral column when the hind legs touch the ground in trot and canter, suggesting that ground reaction forces tend to flex the hip joint and the lumbar spine during these movements.

Conclusion

• The results of the study thoroughly confirmed the predictions made through theoretical biomechanical analysis. They provide insight into the role and importance of the horse’s trunk muscles in maintaining body shape and executing walking, trotting, and cantering movements.