Differences in equine spinal kinematics between straight line and circle in trot
Authors: Byström A., Hardeman A. M., Serra Bragança F. M., Roepstorff L., Swagemakers J. H., van Weeren P. R., Egenvall A.
Journal: Scientific Reports
Summary
# Editorial Summary: Equine Spinal Kinematics on Circles versus Straight Lines Lateral bending during circular work is fundamental to dressage training, yet its biomechanical reality had never been quantified until Byström and colleagues used three-dimensional motion capture to examine how the equine spine actually moves on circles. Twelve horses were trotted on left and right circles and in straight lines on a soft surface without riders, with motion capture markers tracked along the spine at 100 Hz to measure lateral bending angles throughout the thoracolumbar region and neck. The results revealed statistically significant lateral bending toward the inside of the circle in both the thoracolumbar spine (3.75° on left circles, 3.61° on right circles compared to straight-line trotting) and the neck (5.23° and 4.80° respectively), with range of motion also increasing slightly during circular work. Individual horses showed considerable variation in the magnitude of these differences, though each animal demonstrated consistency across repeated trials—a finding that suggests inherent biomechanical preferences rather than random variation. For practitioners, the take-home message is nuanced: whilst the recorded bending angles are modest and may not always be visually apparent, these spinal changes occur alongside unmeasured alterations in muscle recruitment and limb loading that collectively contribute to the horse's observable outline and performance on circles, making this research directly relevant to understanding training effects and assessing individual responses to lateral work.
Read the full abstract on the publisher's site
Practical Takeaways
- •Horses naturally bend their spines and necks to the inside of circles during trotting, supporting the dressage principle of asking for lateral bend on curved lines
- •Back bending differences between circles and straight are small (3-4°) and may not always be visually obvious—focus on overall balance and consistency rather than exaggerated bend
- •Each horse shows individual differences in how much they naturally bend; use this knowledge to work within the horse's biomechanical preferences rather than forcing uniform bend
Key Findings
- •Horses showed increased lateral bending of the thoracolumbar spine toward the inside of circles (3.75° left circle, 3.61° right circle vs. straight)
- •Neck lateral bending increased toward circle direction by 5.23° (left) and 4.80° (right) compared to straight line trotting
- •Lateral bending range of motion increased on circles by 0.87° and 0.62° respectively
- •Individual variation in spinal kinematics was substantial but consistent within horses across multiple trials