02/18/2026
Rethinking Collection: Forehand Organization in the Research of Hilary Clayton
Modern equine biomechanics research increasingly supports what massage therapists, bodyworkers, and skilled trainers have recognized for decades: true collection develops through the horse’s ability to lift, stabilize, and suspend the trunk between the forelimbs.
Seventeen years of kinematic and kinetic investigation led by biomechanics veterinarian Hilary Clayton, BVMS, PhD, DACVSMR, MRCVS, at the McPhail Centre for Equine Performance at Michigan State University have produced some of the clearest objective descriptions of how horses organize their bodies in collection.
Clayton’s findings consistently demonstrate that collection arises from the coordination of the entire horse.
Force-plate and motion analyses show that:
• the hind limbs increase flexion
• they step further beneath the body
• and these adjustments contribute to a broader redistribution of forces
Collection, therefore, is a whole-body event.
The hindquarters provide propulsion and articulation while supporting elevation of the forehand through coordinated interaction with the trunk and front end.
Weight Distribution Explains Why Forehand Organization Is Essential
The average horse carries approximately 58 percent of its body weight on the forehand and 42 percent on the hindquarters. This inherent distribution clarifies why the development of forehand organization is central to achieving an uphill balance.
Clayton’s research demonstrated that the horse learns to direct force upward through the forelimbs, enabling elevation of the trunk. In this arrangement, the hind legs support the body and generate propulsion while the thorax remains lifted.
In simple terms:
• the hind legs push
• the forehand lifts
• the trunk is suspended between them
The Trunk and Chest Are the Keys to Elevation
Clayton’s work showed that during true collection:
• the ribcage and sternum rise between the forelimbs
• the center of mass elevates as part of this action
This occurs through active engagement of the thoracic sling, which raises the body higher between the limbs.
The Thoracic Sling as a Primary Balance System
Unlike humans, horses lack a clavicle. No bony strut joins the forelimbs to the trunk. Instead, the thorax is suspended in a muscular and fascial apparatus commonly referred to as the thoracic sling.
Clayton’s studies confirmed the importance of this system, including:
• the serratus ventralis
• the pectoral musculature
• associated stabilizing tissues
Together, these structures:
• support and elevate the trunk between the scapulae
• demonstrate high activity during collection
• underpin self-carriage
Functional integrity of the sling is fundamental to the development of collection.
This interpretation aligns closely with osteopathic and myofascial models that describe the horse as a suspended, integrated structure.
Forelimbs as Active Participants
Clayton’s work further illustrates that the forelimbs continue to bear substantial load in collection. What changes is the strategy by which that load is organized.
With effective sling function:
• shock absorption improves
• limb timing becomes more elastic
• scapular mobility increases
These adaptations help explain why collection built around trunk elevation is frequently associated with enhanced durability.
Sling Asymmetry and Crookedness
Crookedness may arise from multiple contributors, among them asymmetry within the thoracic sling, particularly in developing horses.
The serratus ventralis spreads from the scapula onto the ribs and toward the base of the neck. Differences in function between sides can influence:
• the height of the withers
• shoulder path
• trunk position
Straightness therefore develops through attention to limb alignment together with symmetrical sling activity, allowing the chest to remain centered and buoyant.
The Role of the Pectorals in Forelimb Control
Clayton also observed that the pectoral muscles increase in strength and cross-sectional area as the chest organizes upward, especially during:
• smaller circles
• accurate turns
• lateral movements
These muscles stabilize the limbs in stance and guide crossing in swing. Their development reflects a posture that is carried rather than held.
Collection as a Coordination Challenge
According to Clayton’s data, collection is supported by:
• neuromuscular coordination
• precise interlimb timing
• trunk stability
• elastic storage and return of energy
Structure and function operate together, and balance emerges from the orchestration of the entire system.
Rider Education Matters
Because thoracic elevation is not always visually dramatic, Clayton emphasized the importance of informed riding.
Her research indicates that:
• thoughtful cues assist the muscles of balance
• rider posture influences trunk mechanics
• stability in the rider encourages stability in the horse
As understanding improves, riders cultivate lift, elasticity, and coordination. Collection then appears quieter, lighter, and more sustainable.
Where Massage and Fascial Therapy Fit
Understanding that collection depends on tissue elasticity and precise neuromuscular timing naturally raises an important question: how can we prepare the system to perform these tasks more easily?
The thoracic sling represents a continuous myofascial network linking limb, trunk, neck, and sternum. Within this network, fascia contributes to force transmission, elastic recoil, and sensory communication.
For effective elevation, tissues must be able to:
• glide
• adapt to changing load
• transmit force efficiently
• deliver accurate proprioceptive information
When these qualities diminish, coordination becomes more difficult.
Massage and myofascial therapy support the conditions that allow coordination to emerge.
By encouraging hydration, sliding surfaces, circulation, and mechanoreceptor responsiveness, bodywork may help the horse access:
• greater trunk freedom
• improved shock absorption
• elastic joint behavior
• refined body awareness
Manual therapy prepares the conditions that allow collection to develop.
The Big Takeaway
Clayton’s research positions collection as the lifting, stabilization, and suspension of the trunk through the thoracic sling.
These findings provide objective biomechanical context for observations long shared by osteopaths, bodyworkers, and accomplished trainers:
• balance precedes power
• elevation precedes engagement
• posture reflects neurological organization expressed through tissue
Together, they continue to shape modern approaches to sustainable performance.
https://koperequine.com/the-bow-the-string-and-the-corset-how-equine-ligaments-and-myofascial-systems-support-movement/
