Electromyography activity of the equine splenius muscle and neck kinematics during walk and trot on the treadmill.

This research focused on studying the activity of the horse’s splenius muscle and its relation to the movement of the horse’s head and neck during walking and trotting, using both kinematic measurements and surface electromyography. The findings showed that muscle activity was maximum at the beginning of the forelimb stance phases in trot, indicating the muscle’s role in preventing, or stabilizing against, excessive movement of the head and neck.

Objective

The purpose of this research was to elucidate the function of the equine splenius muscle during two primary movements, walking and trotting. By focusing on muscle activity and the movement of the horse’s head and neck, the study aims to offer a more comprehensive understanding of equine biomechanics at these gaits.

Methods

• The study involved six horses, aged between 8 to 20 years and weighing 450-700 kg, with no signs of neck pain.
• The researchers placed markers on strategic anatomical locations of the horses—on their left and right facial crests and cervical vertebrae (C1 and C3).
• They used kinematics and surface electromyographic measurements to identify muscle activity, particularly in the splenius muscles located at the C2 neck level.
• Computations for neck and head angles were performed in both sagittal and horizontal planes.

Results

• The maximum surface electromyography (sEMG) values at the trot were higher than at the walk for all horses. The differences between maximum and minimum sEMG values ranged from 45-127 mV during a walk and 154-524 mV during a trot.
• The C1 angle variation was recorded to be 43° during walking and 27° during trotting.
• The study found two EMG peaks in each motion cycle of both gaits, which occurred just before the maximum extension of the C1 angle.
• The C1 angle variation for lateral bending was found to be similar at 16° during walking and 17° during trotting. Maximal sEMG values corresponded with the maximum lateral bending at walk.

Conclusions

The splenius muscle showed the highest activity at the beginning of the forelimb stance phases in trotting—an insight that suggests the muscle’s function in stabilizing the head and neck against flexion. On the other hand, the study did not find the splenius muscle to stabilize the head against lateral movements. Hence the study offers valuable insights into the equine splenius muscle function and can contribute to a better understanding of equine movement biomechanics.