Understanding equine biomechanics is crucial for assessing workload and the risk of injury. Back pain is a common problem many equine veterinarians treat, and one contributing factor may be the training method used or a horse that has a naturally high head set.
Bow and String Theory : The Essence of the Bow and String Theory
Your horse’s spine and pelvis work together to move the body forward . The muscles attached to the sacrum and pelvis are akin to the engine, generating energy for movement. The lumbosacral junction converts this energy into forward motion by storing and releasing tension.
The "Bow and String Theory" provides a biomechanical framework for understanding how potential energy is generated, stored, and released in the spine during locomotion. In this analogy, the "bow" represents the rigid component comprising the bony spinal segments and surrounding ligaments, while the "string" encompasses the horses back muscles, as well as the, hip flexors, abdominals, and cervical flexors like the scalenus.
The rigidity of the ‘bow’ arises from its bony architecture and the dense network of intrinsic ligaments intimately attached to it. When the locomotion muscles contract, they act like strings drawn by an archer, flexing and cocking the bow, thereby storing potential energy in the spine. Upon release of this mechanism, unimpeded by any obstacles, all stored potential energy is converted into kinetic energy, resulting in a net positive gain in energy required for engagement, collection, and movement forward. Any hindrance in the cocking or release process of this mechanism will diminish the net gain of energy and cause the horse overload the front half of the body.
Most often this breakdown occurs because:
Abdominals are weak
Hip flexors are tight
Back muscles are held tight
Weak hind end muscles: Hamstrings, glutes, and quadriceps
Recent studies have examined how different head and neck positions affect horse kinematics, highlighting the importance of proper positioning for optimal performance. Equine performance longevity relies on optimizing biomechanical principles, particularly the positioning of the head and neck axis, which profoundly influences the horse's athletic ability and comfort for both horse and rider. Recent findings have shed light on how different positions affect horse movements, with higher positions often restricting stride length and flexibility.
Specifically:
Very high head and neck position (Neck extremely elevated and bridge of the nose considerably in front of the vertical) significantly reduced flexion-extension movement of the spinal vertebrae, lateral bending of the lumbar back, and axial rotation of the pelvis.
Nose at the vertical, slightly behind, or neutral did not negatively influence flexion-extension movement of the spine, lateral bending of the lumbar back, and axial rotation at walk or trot.
To comply with a high head position, the horse performed at reduced speed and increased peak force on the forelimbs.
A low neck position (long and low headset) increased flexion-extension movement of the spinal vertebrae, but also increased peak force on the forelimbs
In Conclusion
A high head carriage with the nose above the vertical like the sillouette image locks up the back and increases wear and tear in the front half of the body. Most horses look like they are in true collection, and can almost get there by keeping their nose at vertical or neutral, however in this study true collection was rare no matter what level the rider/horse pair.
Once this pattern of carrying the head high becomes a habit, the back and neck muscles eventually contract and shorten around the spine. At this point, chiropractic adjustments are needed to correct the fixated segments.
Horses going through dressage training will never have perfect collection all the time. Therefore the horses I see in heavy training have several areas in the lower lumbar region that are stiff and immobile from incorrectly storing potential energy. Their core maybe weak as well, and back muscles are very tense. With home rehabilitation exercises we are able to supple the back muscles and allow the horse to have a stronger posture to improve their performance.
According to the research, the stiffness of poor posture and improper elevated head carriage was most obvious at the walk. The stride is short and choppy. If this sounds like your horse consider it a warning sign of unnecessary stress and strain. Here at The Zen Vet we can help improve your horse's performance but improving spinal function and flexibility.
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