T H E B O W & S T R I N G T H E O R Y

This biomechanical theory was first proposed by Barthez (1798) and later popularised by Slijper (1946). The model refers to how the horse's spine, muscles and ligaments produce the power in movement.

The "Bow":

Refers to the horse's dorsal chain (red).
Consists of the thoracolumbar spine, epaxial muscles, the pelvis, and the nuchal and supraspinous ligaments.
These provide elastic suspension, while also supporting the head, neck and barrel.

The "String":

Refers to the horse's ventral chain (blue).
Consists of the sternum, ventral abdominal muscles and the linea alba.
These provide the tension needed to stabilise and support the core.

When the "String" creates tension during abdominal muscle contraction, the ribcage and pelvis will be pulled causing the "Bow" to flex, creating rounding of the back.

Alternatively, if the "String" becomes too slack, the "Bow" would consequently extend down and result in the horse becoming hollow in their back.

This theory also involves the horse's limbs; as when they protract and retract, the underline is influenced, resulting in reduced concussive forces and improved hindlimb propulsion.

Why is the "Bow and String" theory important?

This mechanism is extremely relevant in equine performance and soundness as it allows the horse to work while maintaining a correct spinal posture, activate their abdominal muscles (contributing to core strength), increases hindlimb enegagment and will aid the development of a well-conditioned top line.

This theory is only a foundation to equine biomechanics, but still provides insight on how important it is in equitation.

Image: Author's Own (2026)