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When advancing into higher levels of horsemanship, you may seek to understand the complex system that enables your horse to perform optimally. The horse’s carrying system is designed to support the horse's body, absorb shock, and provide balance and stability during movement. It allows the horse to carry its own weight, the rider, and loads with elegance and power.
by Andria Massie, Director & Equine Physiotherapist The Equine Healing Center & Massie Equine Veterinary Clinic
Understanding how this system works is important- it shapes our riding and training approaches and is vital for maintaining horse’s health and peak performance. Without this knowledge, we cannot fully appreciate the demands we place on our horses under saddle. In this article, I’ll walk you through your horse’s anatomy and the mechanics of its carrying system.
Understanding the Horse’s carrying system
Horses aren’t naturally built to carry weight; rather, they’re designed to suspend their weight. The horse's body is structured like a sling system, with support at the front and back, a hanging basket in the middle, and four supporting pillars. For a horse to carry weight effectively, all these parts must work together seamlessly. Let's explore the four critical components below:
The Thoracic Sling
Unlike humans, horses lack a collarbone to connect their front limbs to the trunk and hold their chest cavity in place. Instead, they rely on a strong mechanism of ligaments, fascia, and muscles that act like "slings" to suspend the chest between the front limbs, hence the term "thoracic sling."
The thoracic sling is a complex network of muscles and connective tissues that supports the horse’s chest cavity between its front limbs. It includes the shoulder, wither, and neck muscles.
The primary components of the thoracic sling are the M. Serratus Ventralis (cervical and thoracic), supported by the pectoral group. It’s an integral part of your horse’s carrying system because it helps lift the back and withers and activate their core.
When functioning correctly, the thoracic sling lifts the horse's chest, allowing for good vertical and horizontal balance. When dropped or inactive, the horse tends to lean on the forehand and become unbalanced.
It is important that the thoracic sling muscles are in good condition to enhance posture and biomechanics. Unfortunately, this region is often underdeveloped or compromised in many horses, leading to stiffness, poor balance, and reduced mobility. I regularly observe horses not moving forward freely and leaning on the bit due to compromised or weak thoracic sling muscles.
Addressing these problems requires rest, targeted exercises, and sometimes veterinary intervention. Strengthening exercises, such as core training and controlled downhill walking, can activate the thoracic sling muscles.
The Pelvic Girdle
The pelvic girdle, or sublumbar muscle group, consists of four muscles extending from the lower end of the thoracic and lumbar vertebrae to the front of the pelvis and femur. This structure includes the pelvis, sacrum, and surrounding muscles and serves as a pivotal point for transferring forces between the hindquarters and the spine.
In simple terms, the pelvic girdle is the engine of your horse. It is instrumental in the dorsiflexion and ventriflexion of the spine, providing stability to the vertebral column and pelvis. A strong pelvic girdle is essential for the hindquarters’ strength and propulsion. Your horse relies on this region to perform dynamic activities like leaping and galloping.
Issues with the pelvic girdle lead to altered gait and performance. Proper conditioning, regular exercises with solid warm-up routines, and attention to any discomfort or imbalance can help maintain a healthy pelvic girdle.
The Abdominal Basket
The abdominal basket houses the horse's vital organs and ribcage, supported by a network of muscles and connective tissues. Like humans, horses need a strong core to stay fit and prevent injuries. The abdominal muscle group is an essential part of the core muscles that stabilize the pelvis and back.
Strong abdominal muscles provide a stable base for the horse to engage the deep muscles connecting the pelvic limbs and spine, leading to quality and controlled movement. This stability reduces the risk of injuries, as your horse can better cope with sudden changes like uneven terrain or slipping. It also improves posture and enables the horse to carry the weight of a rider by lifting through its back.
One thing to remember is that horses achieve physical balance from the inside out, beginning with the central axis of their bodies. Good center coordination radiates throughout the entire body and dictates the use of the legs, neck, head, and other body parts. A strong core also increases the soft tissues' ability to protect the spine from injury or re-injury.
Core-strengthening exercises, such as belly lifts, carrot stretches, backing up, polework, and targeted groundwork, improve the strength and flexibility of the abdominal muscles and activate the horse’s core.
The Pillars of Support - The Legs
The legs are the horse's pillars of support and shock absorbers, yet they are also its most vulnerable points. Understanding the mechanics of equine legs is vital for preventing injuries and extending the horse's career.
The front legs primarily support the horse's body and absorb shocks during movement. They are positioned closer to the horse's center of gravity than the back legs, making them more susceptible to injuries, especially during high-impact activities like jumping. The back legs, on the other hand, propel the horse forward, carry its hindquarters, and provide power and agility during jumps.
Horses naturally carry a larger proportion of their weight (about 60%) on their front limbs, leading to increased stress in these areas. A horse's conformation and previous training will determine how much it relies on its forehand for balance.
Training a horse to shift excess weight from the forelegs to the hindquarters is not straightforward. I usually begin by gradually encouraging each hind limb to step further under the horse's center of gravity. With consistent practice and targeted exercises, the horse can better support its weight and that of the rider in motion.
Common leg problems include abscesses, laminitis, tendon, ligament, or joint injuries, and degenerative diseases that cause lameness. Proper nutrition, regular hoof care, appropriate exercise, and prompt injury treatment are essential for maintaining leg health.
Final Say
Every component of the horse's carrying system is vital to its overall health and performance. When all parts are in sync, the horse achieves horizontal and vertical balance. I believe this article has deepened your understanding of your horse’s structure and how to maintain its balance for optimal performance. With this knowledge, you can spot anomalies in your horse’s movement.
At The Equine Healing Center and Massie Equine Veterinary Clinic we address a range of equine concerns, from training routines to problems with conformation and balance. If you have questions or need assistance with an equine restorative fitness plan for your horse, get in touch with me and we can schedule an in person or virtual evaluation and coaching session.
