Electromyography activity of the equine splenius muscle and neck kinematics during walk and trot on the treadmill
Authors: ZSOLDOS R. R., KOTSCHWAR A. B., KOTSCHWAR A., GROESEL M., LICKA T., PEHAM C.
Journal: Equine Veterinary Journal
Summary
# Editorial Summary: Splenius Muscle Activity and Neck Kinematics in the Horse Understanding how the splenius muscle contracts during movement is fundamental to interpreting neck biomechanics and diagnosing functional limitations in ridden horses. Zsoldos and colleagues used surface electromyography combined with marker-based kinematic analysis in six sound horses to characterise splenius muscle activity patterns during walk and trot, placing particular emphasis on the relationship between muscular contraction timing and cervical vertebral motion in multiple planes. Peak muscle activity more than tripled during trotting compared to walking (ranging from 154–524 mV at trot versus 45–127 mV at walk), with two distinct activation peaks per stride cycle occurring just prior to maximum C1 extension in both gaits. Notably, the splenius muscle functioned primarily as a dynamic stabiliser against dorsal flexion at the beginning of forelimb stance rather than providing unilateral control of lateral neck bending, suggesting that other cervical musculature may be responsible for lateral stabilisation. For practitioners involved in neck assessment and rehabilitation, these findings indicate that splenius dysfunction would most significantly compromise the horse's ability to stabilise the cranial neck during weight-bearing phases of locomotion, rather than affecting lateral flexibility as traditionally assumed.
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Practical Takeaways
- •Splenius muscle activity peaks during the forelimb stance phase at trot, suggesting it functions to stabilize the head and neck against flexion—understanding this may inform assessment of neck pain or poor posture
- •The substantially higher muscle activation at trot compared to walk indicates different biomechanical demands between gaits, which could be relevant when evaluating horses with gait abnormalities or neck issues
- •Normal neck kinematics show substantial flexion-extension range at C1 (27–43°), providing a baseline to compare against horses with restricted or abnormal neck movement
Key Findings
- •Maximum sEMG values at trot were significantly higher than at walk, with ranges of 45–127 mV in walk and 154–524 mV in trot
- •Splenius muscle reached maximum activity just prior to maximum extension of the C1 angle in both gaits, with 2 EMG maxima per motion cycle
- •C1 flexion-extension angle changed by 43° during walk and 27° during trot
- •Bilateral splenius activity increased during lateral bending at C1, but unilateral stabilization against lateral movement was not demonstrated