Young racehorse development through the lens of biotensegrity and fascia science

The debate surrounding the appropriate age to commence racehorse training remains a contentious topic. Advocates of traditional biomechanical models argue that training at 18 months is premature, as a horse's skeletal system does not reach full maturity for several more years. However, skeletal development alone presents a limited perspective. I would like to introduce another perspective from a rising research field. Through the lens of biotensegrity and fascia science, a more comprehensive approach emerges—one that considers the interconnectedness of a horse’s entire physiological system. Well-structured training at a relatively young age can support the holistic development of the racehorse, fostering both physical and psychological adaptability.

The Influence of gravity and early adaptation

From the moment a foal is born, it must quickly adapt to the force of gravity. Passage through the birth canal initiates its structural alignment, and within hours, the foal is standing and moving independently. Foals are born with predominantly fast muscle fibres (2X). The ability to travel up to seven kilometers daily alongside its dam is a testament to the foal’s inherent adaptability. This early exposure to movement and environmental stimuli plays a crucial role in its physiological and neurological development.

Challenging traditional views on skeletal maturity

This article seeks to introduce an alternative perspective on how the horse interacts with gravity, incorporating the principles of biotensegrity and fascia. It is important to note that most research is done on corpses and the fascia dries out almost directly after the circulation stops. Traditionally, equine skeletal maturation has been the primary concern regarding the timing of racehorse training. However, a singular focus on bone development overlooks the adaptability of connective tissues and the overall structural integrity of the horse. All young horses as an adaptation to their environment are in a critical phase of learning and adaptation—both physically and mentally—which must be accounted for in any training approach.

Veterinary discourse on skeletal maturity presents conflicting perspectives. Veterinarian Chris Rogers asserts that the skeleton of a two-year-old Thoroughbred is sufficiently developed for training, drawing parallels to human child development. Conversely, Dr. Deb Bennett posits that full skeletal maturity does not occur until six to eight years of age regardless of breed. All horses go through almost the same skeletal development phases, although thoroughbreds are extremely adapted through breeding to grow much quicker. While Bennett’s perspective has been widely accepted, Rogers’ viewpoint aligns with the practical realities of racehorse development, supporting the industry’s traditional training timelines.

Flat racehorses typically begin training at around 18 months of age. At this stage, their skeletal and connective tissues are still developing, as research consistently shows. Cartilage, bones, muscles, and ligaments undergo intensive growth and adaptation. Every experience the young horse encounters contributes to its physiological and neurological development, shaping its ability to perform the tasks expected of a racehorse. Training at a young age offers several advantages, as young horses are highly receptive and adaptable. As explored later in this article, their connective tissues develop in response to the challenges they are exposed to, reinforcing their structural integrity over time.

Racehorse training inherently involves a selection process. Horses that do not meet performance expectations within the first few seasons are often retired from racing by the age of three or four, making way for new yearlings. Those that demonstrate both speed and durability may continue competing well into their later years.  Those are often geldings. Mares and stallions that show promise may transition into breeding programs. The rest, if their foundational training has been well-structured, can adapt successfully to second careers as riding horses, often becoming ideal partners for young equestrians at the start of their horsemanship journey.

Tensegrity principles

Tensegrity (tensional integrity) is a structural principle that explains how forces of tension and compression interact to create stability in a system. Originally coined by architect and engineer Buckminster Fuller, tensegrity has been widely applied in biological systems, including human and equine anatomy.

The role of fascia and biotensegrity in equine development

A traditional biomechanical view perceives the horse's skeleton like a rigid brick wall—if one part weakens, the entire structure becomes vulnerable to collapse. In contrast, a tensegrity-based perspective views the horse as a dynamic suspension bridge, where forces are distributed across an interconnected network of fascia, tendons, and ligaments. In this model, the skeleton is not a rigid load-bearing framework but rather ‘floats’ within the fascial system, allowing for adaptability, resilience, and efficient force distribution.

Biotensegrity highlights the balance between tension and compression within the body. In equine anatomy, the skeleton functions as a stabilizing framework, while fascia, tendons, and ligaments manage dynamic forces. Fascia, composed predominantly of collagen, exists in various densities, from loose connective tissue that facilitates muscle glide to the more rigid structures forming tendons and bones. This complex, fluid-filled network plays a crucial role in maintaining stability, distributing forces, and mitigating the impact of training. 

Training influences the structural adaptation of connective tissues. Properly executed, it can enhance durability and resilience, reinforcing ligaments and tendons much like steel cables under controlled tension. Understanding the dynamic interplay between muscle, fascia, and skeletal development allows for training methods that optimise long-term soundness and performance.

Fascia

One of the most abundant proteins in the body is collagen, which forms connective tissue in all its various forms—from loose fascia, which separates muscles, to denser collagen structures that align with the direction of force and develop into tendons, ligaments, or bone. One of the key functions of loose fascia is to allow muscles to glide smoothly against one another without friction when one muscle contracts and another stretches.

Loose fascia consists of a collagen network, with its spaces primarily filled with water and hyaluronic acid. It is a highly hydrated structure—young horses are composed of approximately 70% water. Imagine a water-filled balloon, where the skin acts as the boundary between the internal and external environments. During fetal development, collagen structures form first, providing the framework within which the organs develop. Collagen, a semiconductive protein, relies on water to function optimally. 

The water-rich environment surrounding fascia transforms it into an extraordinarily intelligent communication network. Its function is highly responsive to the body's pH levels, adapting moment by moment to internal conditions. As the central hub for force transfer and energy recycling, fascia provides immediate balance and support—often operating beyond the constraints of the nervous system.

Fascia's remarkable adaptability is rooted in its multifaceted properties. It is nociceptive, meaning it is capable of detecting pain and harmful stimuli, alerting the body to potential injury or strain. It is also proprioceptive, enabling the body to sense its position and movement in space, which aids in maintaining coordination and balance. Additionally, fascia exhibits thixotropic properties—allowing it to shift between a gel-like state and a fluid-like state depending on movement, which enhances flexibility and responsiveness. 

Finally, fascia demonstrates piezoelectric properties, generating electrical charges in response to mechanical stress, playing a crucial role in cellular signaling and tissue remodeling. These combined characteristics enable fascia to dynamically adjust to both mechanical and biochemical stimuli, ensuring optimal function in response to ever-changing internal and external conditions."

Fascia has no clear beginning or end; it distributes pressure and counteracts the force of gravity.

The biotensegrity of equine locomotion and how horses rest while standing

Horses possess a remarkable evolutionary adaptation that allows them to rest while standing, a capability underpinned by the principles of biotensegrity. This structural efficiency is achieved through an intricate network of tendinous and ligamentous locking mechanisms working in harmony with the skeleton.

In the forelimbs, the extensor and flexor tendons engage to stabilise the skeletal structure, minimizing muscular effort. Meanwhile, in the hind limbs, a specialised locking mechanism is activated when the patella (kneecap) is positioned against a flat section on the femur just above the stifle, further contributing to this passive support system.

This adaptation allows horses to conserve energy while remaining poised for rapid movement. In the event of sudden danger, they can instantly transition from rest to flight, ensuring their survival—an essential trait for both wild and athletic performance. The efficiency of this natural support system exemplifies the principles of biotensegrity, where tension and compression forces work in balance to maintain structural integrity with minimal effort.

The head and neck function as critical balancing structures, comprising approximately 10% of the horse's total body weight. The forelimbs bear roughly 60% of the body’s weight, but true structural support originates from above the elbow joint. The spine, a central element of equine biomechanics, acts as a suspension system. The primary function of the equine spine is to support the internal organs, a role that also enables the horse to carry a rider. 

This structural foundation ensures both stability and balance, allowing for efficient movement and performance under saddle. The propulsion generated by the hind legs is efficiently transferred to the forehand through the back muscles, which are reinforced with robust connective fascia plates, ensuring optimal movement and stability. This structural complexity underscores the need for a training regimen that respects the developmental timing of multiple interrelated systems beyond just the skeletal framework.

Risks and adaptations in young racehorses

While early training offers advantages in developing resilience in young racehorses ( they have a high percentage muscle fiber 2X), it also presents risks. The spinal column, particularly the lumbar-sacral junction, endures significant forces during high-speed galloping. Without appropriate conditioning, the vulnerability of these structures can lead to pathologies such as kissing spines or pelvic instability. Their growth plates remain open, making them more susceptible to the impact of high-speed forces, compensatory adaptations to early training stress may manifest as different maladaptive adaptations in connective and skeletal tissues, potentially diminishing long-term performance capabilities.

However, when managed correctly, the high adaptability of collagen structures in young horses allows for positive adaptation. Training introduces controlled tensile and compressive forces, fostering the development of strong, functional connective tissues. The challenge lies in striking the right balance between stimulus and recovery to optimise long-term soundness and athletic potential.

The value of tacit knowledge in training practices

Experienced trainers have an intuitive understanding of the complex relationships between tissues and biomechanics, a knowledge that is often honed through years of careful observation and practical experience. This tacit expertise is fundamental in shaping training strategies that take into account the horse’s overall development. A comprehensive training program should not only focus on the maturation of the horse’s bones but also prioritise the adaptive growth of fascia, ligaments, and muscles. By doing so, trainers ensure that young racehorses develop in a way that is aligned with their evolving physiological capabilities, promoting balanced growth and minimizing the risk of injury. This holistic approach allows for the optimal performance and longevity of the racehorse, fostering a more sustainable path toward peak athleticism.

Conclusion: a holistic perspective on racehorse development

The evolution of equine training methodologies has greatly benefited from recent advancements in scientific understanding, offering a more refined approach to racehorse development. By incorporating biotensegrity principles into training programs, a more comprehensive view of the horse’s physical structure and function emerges, shifting the focus from skeletal maturity alone to a broader understanding of the interconnected roles of fascia, connective tissues, and adaptive biomechanics. This shift in perspective allows for the cultivation of healthier, more resilient athletes who can perform at their peak while minimizing the risk of injury.

With equine welfare at the forefront, adopting a holistic approach to racehorse development—one that blends cutting-edge biomechanics, physiological insights, and traditional training wisdom—will pave the way for more sustainable, ethical practices within the industry. Such an approach not only enhances performance in the short term but also ensures the longevity and well-being of racehorses throughout their careers. Ultimately, by embracing this integrated perspective, the racing industry can promote a future where both the performance and welfare of horses are prioritised, leading to a more ethical and effective standard of training.

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Extra Reading References 

- Levin, S. (Biotensegrity: www.biotensegrity.com)  

- Clayton, H. M. (1991). *Conditioning Sport Horses*. Sport Horses Publications.  

- Adstrup, S. (2021). *The Living Wetsuit*. Indie Experts, P/L Austrasia.  

- Schultz, R. M., Due, T., & Elbrond, V. S. (2021). *Equine Myofascial Kinetic Lines*.  

- Bennett, D. (2008). *Timing and Rate of Skeletal Maturation in Horses*.  

- Rogers, C. W., Gee, E. K., & Dittmer, K. E. (2021). *Growth and Bone Development in Horses*.  

- Ruddock, I. (2023). *Equine Anatomy in Layers*.  

- Myers, T. W. (2009). *Anatomy Trains (2nd Edition)*. Churchill Livingstone.  

- Diehl, M. (2018). *Biotensegrity*.  

- Kuhn, T. S. (1962). *The Structure of Scientific Revolutions*. University of Chicago Press.

- Tami Elkyayam Equine Bodywork

Lower limb anatomy and how it can be conditioned for racing

Article by Adam Jackson MRCVS 

Better understanding the appropriate levels of exercise and training while the horse’s body grows and develops has been a topic of research for many years. Although it has been shown that young, growing horses are well-suited to adapt to conditioning, it is vital that continued research is performed in order to develop thoughtful and strategic training methods to promote healthy, fit and sound horses with long careers and lives.  

Horses’ limbs consist of dozens of muscles, bones, tendons, ligaments, and joints that allow the horse to move as well as support its body weight. The limbs function to provide thrust and movement while absorbing impact and bearing weight.  Most of the horse’s weight is supported by the fore limbs, while the propulsion of the horse is provided by the hind limbs. In addition, the horse has two apparatuses referred to as the stay apparatus and suspensory apparatus. The stay apparatus allows major joints in the limbs to lock so that the horse may rest and relax while standing. The suspensory apparatus is designed to absorb shock, carry the horse’s weight, and prevent the overextension of joints. Finally, the hooves are important structures that maintain support and traction as well as provide additional shock absorption.  

Since the cardiovascular system provides blood supply throughout the body, by responding to various stimuli, it can control the velocity and amount of blood carried through the vessels, thus, delivering oxygen, nutrients, hormones, and other important substances to cells and organs in the body.  It plays a very important role in meeting the body’s demands during exercise, stress, and activity.  

Exercise is used to increase the body’s ability to withstand repeated bouts of similar exercise with less impact.  With a strong and healthy cardiovascular system, there is an improved ability of the musculoskeletal system receiving oxygen, thus, allowing muscles to better their capacity to use oxygen and energy.  However, the adaptation period for each of these physiological systems do differ as the cardiovascular system adapts faster compared to the musculoskeletal system. This is often an overlooked consideration when developing training programmes for horses. 

It is important to understand the various functions, structures, and adaptive processes of the horse’s musculoskeletal system such as bone, articular cartilage, tendons, and ligaments in order to develop appropriate training regimens. 

Bone has many important roles that involve locomotion, the storage of minerals (especially calcium and phosphate), soft tissue and vital organ protection, and the support and containment of bone marrow. Bone is a specialised connective tissue, and together with cartilage forms the strong and rigid endoskeleton.  The bone is continuously altering through two processes called bone modelling and bone remodelling, involving four cells referred to as osteoclasts, osteoblasts, osteocytes and bone lining cells.  

Osteoblasts secrete bone matrix in the form of non-mineralised osteoid, which is then mineralised over a few weeks to form a bone matrix.  Osteoclasts are involved in resorption of bone as this process occurs faster than the formation of bone. When the bone surfaces are not in the development or resorption phase, the bone surface is completely lined by a layer of flattened and elongated cells termed bone-lining cells.  Osteocytes are derived from osteoblasts and are highly specialised to maintain the bone matrix.  They are designed to survive hypoxic conditions and maintain biomineralisation of the bone matrix.  Osteocytes also control osteoblastic and osteoclastic activities allowing bone remodelling.

The function of bone modelling is to alter and maintain shape during growth. As the horse grows and develops, bone modelling occurs with the acquisition and removal of bone.  While the young horse grows and develops, bone modelling allows the bone to endure strains from everyday work and exercise. The adult skeleton undergoes a minimal amount of bone modelling. Due to the presence of the high frequency of bone modelling in young horses, their skeletal strength is highly influenced by strains to their bones during exercise and daily use. With this knowledge, it has been concluded and confirmed that short-term dynamic exercise of an adolescent can lead to beneficial changes to its bone morphology.  

Bone remodelling is a different process, in which old and damaged bone is renewed, which enables the bone to respond and adapt to changing functional situations. Bone remodelling is usually a coordinated relationship between bone resorption and bone formation. This process occurs throughout the horse’s life with the renewal of primary, damaged or old bone. Osteoclasts absorb old and damaged bone, and the osteoblasts form new bone and lay down new bone matrix until the earlier absorbed bone is replaced. In those animals with musculoskeletal disease or damage, there is an imbalance of osteoblast and osteoclast activity. With the knowledge that osteoblast activity to make new bone takes months whilst osteoclast activity of removing old and damaged bone only takes a few days to two weeks, bone that is being repaired is at a high risk of further injury as bone removed has not been completely replaced.   Multiple studies have shown that exercise while growing can provide lifelong benefits; however, it must be done with care and knowledge.

In addition, many studies have shown that exercise of a dynamic nature in moderate distances, such as that achieved in the pasture or prescribed short-distance high-speed work is beneficial to musculoskeletal development and may prevent injuries when entering race training. It has also been observed that long slow work does not increase bone strength. Below is a summary of the young horse response of the various types of exercise.

Articular cartilage is a highly specialised connective tissue found in joints with the role of providing a smooth, lubricated surface of articulation and to help transmit loads with a low amount of friction. The articular cartilage is a hyaline cartilage (flexible and strong tissue providing a smooth, slippery surface) with a dense “ExtraCellular Matrix” (ECM) consisting of specialised cells called chondrocytes, collagen and proteoglycans. These components help to retain water in the ECM that is required for the joints mechanical properties. As age increases, hydration of the matrix does decrease, resulting in stiffness. Chondrocytes are residential cells in articular cartilage that play a role in the development, maintenance, and repair of the ECM. They do respond to a variety of stimuli, including mechanical loads, growth factors, hydrostatic pressures, piezoelectric forces (formation of electric charge with force). Because of the lack of blood vessels, lymphatics, and nerves as well as being a harsh biomechanical environment, there is a limited capacity to heal and repair. In addition, chondrocytes have limited potential for replication, thus, have limited healing capacity; and chondrocytes survival depends on an optimal chemical and mechanical environment.  

Maintaining joint health is vital, which requires the preservation of healthy cartilage tissue. Inactivity of joints is detrimental to articular cartilage; thus, regular movement of joints and dynamic loads is needed to provide a normal articular cartilage structure and function. Biochemical responses of the cartilage to exercise are not nearly as well known compared to bone. While the confinement of young horses stunts joint development, excessive straining of cartilage can also reduce joint development. It has been observed that pasture access was optimal for the development of joints and the confinement or excessive sprint exercise (12–32 sprints of 40 metres for 6 days a week for 5 months) causes detrimental effects on the joint and may be deemed as unnatural exercise.  It is also thought that exercise is needed well before two years of age to allow cartilage thickening as well as the avoidance of confinement. It can be concluded that further studies are required with respect to level of exercise and type of exercise in order to achieve healthy cartilage tissue as there is clearly a fine line between frequency and intensity of exercise.  

Tendons and ligaments are distinct but closely related tissues that have unique and important roles in musculoskeletal function and musculoskeletal disease. Tendons and ligaments are dense, fibrous connective tissues that connect muscle to bone or bone to bone, respectively.  These tissues transmit mechanical forces to stabilise the skeleton and allow body movement.  Tendons and ligaments consist mainly of collagen type I as well as small amounts of collagen III, IV, V, and VI. There are also various proteoglycans in tendons and ligaments that both organise and lubricate collagen fibre bundles. The elasticity of tendons and ligaments is due to the large amount of type I collagen. During locomotion, the tendon decreases energy cost to the horse by acting as a spring to store and release energy while stretching and recoiling in the stance and swing phases of each stride. Tendons and ligaments have blood vessels and nerves that allow the homeostasis and response to injury.  

Tenocytes are tightly regulated by a series of growth factors and transcription factors that allow the synthesis, maintenance, and the degradation of the tendon extracellular matrix. Tendons are elastic, but tearing may occur if there is excessive loading on the tendon and the repair of collagen is a slow process. In addition, tendons have crimp morphology where the tendons buckle in a state of relaxation and act as shock absorbers.  Unbuckling of the tendon occurs during loading.  This crimp morphology may be disturbed if an injury occurs and also is reduced in older horses.  

Due to the variation of activity of tenocytes in foals and young horses, it has been observed that both a lack of exercise and excess of exercise can impair tendon make-up and subsequent functionality. With the current data and research that has been gathered, it can be concluded that if horses take advantage of spontaneous exercise when in the paddocks (which they often do), the developing tendons may benefit and be at a lower risk of injury when racing training starts. 

Conclusion

It is clear that further research is needed in order to ascertain the optimal amount and type of exercise that is needed in order to provide a strong musculoskeletal system and functional performance. However, it has been shown that prescribed exercise during the growth of the horse can increase the longevity of the horse’s health and performance. It has been observed that confinement and the lack of loading can result in weaker tissues and the loss of function of none, tendons, ligaments and articular cartilage.  However, it must also be recognised that medical attempts to alleviate pain so that a horse can continue to train through an injury can greatly increase tissue damage which is detrimental to the horse’s health and career. It is far more beneficial to provide an adequate amount of time for the injury to heal, thus, putting the horse’s health and wellbeing as a top priority.  

Nutritional Perspective

Bone development in yearlings from the sales ring to racing

Article by Des Cronin B.Ag.Sc, MBA

Maintaining the equine skeleton is vital to ensure optimal development of the young growing horse, minimise risk of injury in the performance horse, and promote longevity and soundness.

The skeletal development and health of a young horse begins in utero and ensuring the broodmare receives the correct intake of key nutrients will be critical to the growth of the unborn foal. Producing high-quality milk places a significant drain on the mineral reserves of the mare. Maintaining mineral intakes during peak lactation is vital to ensure the foal receives the best nutrition to support the rapid skeletal development in the early weeks and months of growth. During this time, bone formation, body size, and muscle mass greatly increase. Risk of defective bone and related tissue formation increases with one of more of the following:

• Poor diet with the incorrect balance of energy and nutrients in the daily ration

• Inadequate amounts of calcium (Ca) and phosphorus (P)

• A reversed Ca:P ratio

• Low zinc (Zn) or copper (Cu) in the diet

• Low Vitamin D

Feeding a young horse for a maximum growth rate is undesirable because bone hardening lags greatly behind bone lengthening. At 12 months old, the young horse could reach about 90 to 95 per cent of its mature height but only about 75 per cent of its mature bone mineral content.

Ideally, young horses should gain weight at a rate that their developing bones can easily support. Growing bones and connective tissues don’t have the strength to support rapid weight gain from overfeeding, especially energy. Rapid weight gain can also make other skeletal anomalies worse. In these cases the risk of developmental orthopaedic disorders (DOD) and unsoundness increases.

DOD and unsoundness can also occur during uneven growth. For example, switching an underfed, slow-growing horse to a good diet that allows quick growth (compensatory growth), increases the risk of DOD. Foals between the ages of 3 and 9 months of age are at greatest risk of DOD.

Fresh forages, for example grazed grass, usually provide enough major minerals such as calcium (Ca) and phosphorus (P) for the growing horse. However, there can be significant variation in calcium and phosphorus levels in all forages but particularly preserved forages (hay and haylage). Forage analysis should always be undertaken to determine mineral composition. 

For young fast-growing horses, the diet must supply the quantities of calcium and phosphorus needed for normal bone formation. In terms of Ca:P ratio, the ratio must be positive in favour of calcium. Horses are much more tolerant of high-dietary calcium than other species. For practical purposes, a good guideline would be to keep the ratio Ca:P between 1.5 to 1 and 2.5 to 1.  Grains (e.g., oats) contain 10 per cent of the calcium level found in typical forages. Grains are poor sources of calcium, both in terms of the amount of calcium supplied and their effect on Ca:P ratio in the diet. Where grains are fed, supplementation will be necessary to balance the diet.  

While some forages may contain adequate calcium and phosphorus, they will typically supply less than 20 per cent of the daily requirements for trace elements. Supplementation of trace elements will generally be necessary to support normal bone development.

Where concentrates are fed (especially low levels), supplementation may still be necessary to balance the overall mineral and trace element intake. Nutritional advice should be sought to ensure the horse's diet is correctly balanced.

To meet the carefully balanced requirements of key minerals, it is advisable to supplement the daily rations of growing horses and young horses entering training with an appropriate nutritional product. 

Make sure that the supplement used contains the correct ratio of calcium and phosphorus, as well as other key nutrients such as vitamin D and chelated trace elements (copper, manganese, and zinc) to support normal bone development.

Supplementing branch chain amino acids in the diet ensures that growth is maintained. Lysine plays a key role when protein concentrations in the body are low. Vitamin A supports collagen formation, which is a key component of the supportive structures of joints (tendons and ligaments). Vitamin D3 is added to enhance calcium absorption.

Although growth rates slow after the age of two, they are still juvenile in their skeletal development with some growth plates, such as the shoulder and stifles, yet to completely close. Although they may look like fully grown adults, it is still important to meet nutritional requirements especially if starting training and work. With the addition of exercise and training, a young horse's nutritional needs change.  The added forces from groundwork on the long bones and increased requirements of other nutrients like electrolytes need to be considered. 

Finally, horses all grow and develop at different rates because of factors such as genetics. Some youngsters will need  more support for longer periods of time than others, so it is important to manage accordingly.