Surface electromyography and joint angle kinematics of horses at walk and trot on a treadmill.

Overview

• This study investigated muscle activity and joint movement in horses walking and trotting on a treadmill using surface electromyography (sEMG) and kinematic analysis.
• Researchers aimed to understand how specific muscles and joints function differently between walking and trotting gaits in sport horses.

Study Objectives and Design

• Evaluate muscular electrical activity and joint angle kinematics in horses during walk and trot gaits.
• Subjects: Eleven Brazilian Sport Horses trained for Eventing.
• Conditions: Two gait speeds on a treadmill—walk at 1.8 m/s and trot at 3.6 m/s.
• Design: Completely randomized to assess gait-related biomechanical differences.

Methods: Data Collection Tools and Muscles Analyzed

• Surface Electromyography (sEMG):
  • Measures electrical activity of muscles to infer muscle activation patterns.
  • Used disposable bipolar surface electrodes connected to Miotool Fisio® equipment.
  • Data processed via Miotec Suite 1.0 software.
  • Muscles monitored bilaterally included:
    • Thoracic limb: extensor carpi radialis and flexor carpi ulnaris.
    • Pelvic limb: tensor fascia latae and biceps femoris.
• Kinematic Analysis:
  • Used GoPro camera to record joint movement during treadmill exercise.
  • Focused joints: carpal (wrist area), coxofemoral (hip), and femorotibiopatellar (stifle/knee joint).
  • Joint angles analyzed in KINOVEA software to assess range and timing of motion.

Key Findings on Muscle Activity at Walk and Trot

• Thoracic Limb Muscles:
  • Extensor carpi radialis: Greater activity during forelimb extension at walk, supporting limb stabilization. At trot, it primarily acts as a stabilizer rather than producing movement.
  • Flexor carpi ulnaris: Active during carpal flexion at walk; its role shifts to mainly stabilizing the joint during trot.
• Pelvic Limb Muscles:
  • Tensor fascia latae: At walk, serves to stabilize and flex the femorotibiopatellar joint; during trot, shifts to mainly driving coxofemoral joint extension, indicating functional transition depending on gait.
  • Biceps femoris: Acts to stabilize and propel the limb, especially in the stance phase at trot; shows increased activity with coxofemoral extension supporting forward movement.

Implications of Findings

• Trotting increases biomechanical demands on muscles leading to:
  • Greater muscle recruitment overall.
  • More dynamic shifts in muscle function compared to walking.
  • Increased need for limb stabilization during faster gait.
• The study reveals gait-specific roles of key muscles that could inform equine training, rehabilitation, and biomechanical modeling.
• Understanding these muscle-joint interactions helps optimize performance and injury prevention in sport horses.