Fascia is often the forgotten tissue of the musculoskeletal system and until relatively recently was thought to be irrelevant. However, a greater understanding of horse movement, injury, perception, coordination, transmission of muscle force, biomechanics and the adaptations of the fascial system, have shown the importance of this tissue. There is not a vast amount of research into the equine fascial system, but human fascia research has become more prevalent over recent years as its importance has become more apparent. More research into equine fascia is coming through, however some of the human data can be extrapolated for use in the equine sphere, as in 2017 Skalec & Egerbacher investigated the structure and innervation of the deep fascia of the equine forelimb. Using dissection, histology and immunohistochemistry, they found that the general structure of the equine forelimb fascia corresponds to the characteristics of the human limb fasciae. However, Ahmed et al. in 2019, examined the histological differences between horse and dog fascia at specific regions compared with the human model, finding equine fascia exhibits a tight, dense composition, while in the dog’s is looser with non‐dense structure. Equine fascia appears to be different from canine and human fascia, whilst canine fascia is very comparable to the human model. This shows the need for more specific equine fascia research.The Fascial System The fascial system in horses, people and dogs is an intricate complex interconnected network of tissue encompassing all fibrous connectie tissue, enveloping muscles, bones and organs individually and connecting them. Fascia wraps around nerves, blood vessels and other structures forming an uninterrupted, three-dimensional web. This continuous mesh travels through the entire body as one net with no separation from top to toe, or from skin to core. Fascia keeps the body organised, creating shape and function, and is therefore involved in overall musculoskeletal health. It holds the musculoskeletal system together, pulling in on tissues as they press out as a tensegrity system. Due to the proprioceptive capacity of fascia and its influence on sensation signals between body and brain, the fascial system can be classed as the largest sensory tissue, therefore is required for structural integration, stability, balanced movement and postural compensation. It is the organ of stability and mechano-regulation determining how a body is able to move and is necessary for muscles to function with approximately 30% of force transmission occurring through fascia. Findley et al., 2015 studied the transmission of muscle force to fascia during exercise and found that substantial forces are experienced laterally through fascial tissues when muscle shortens. Fascias’ composition is varied depending on its location and role within the body. Most is composed of dense, closely packed collagen fibres in layers of thick fibrous bundles with sparse elastic fibres covered by loosely woven laminae of areolar connective tissue. Nerve fibres and blood vessels are throughout; numerous in the areolar tissue but scarcer in the compact layers. However, some fascia is extremely intricate like the delicate meningeal fascia of the nervous system. Fascias’ multi-layered composition of various densities, textures, molecular and cellular components is thought to facilitate resistance to gravitational forces, volume changes and transmission of muscle force during movement. Deep profunda fascia under the superficial layer is dense fibrous sturdy tissue in some areas but is less developed in others. Some deep fascia supports core structures such as the dura matter, mediastinum, pericardium, diaphragm and pelvic floor. Deep fascia can be divided into 2 types; aponeurotic and epimysial fascia. The aponeurotic fascia envelops muscles connecting them, forming compartments of limbs and fascia septae between muscle groups, it is thick and tightly attached to the underlying muscle, while the epimysial fascia is specific for each muscle defining it. In areas of force transmission and movement change, stability is needed; these areas are covered with aponeurotic fascia, e.g. the lumbar back and ventral line. In areas where more movement is needed, fascia is thinner, providing proprioception for refined movement. Retinacula areas are all over the body, which sense movement and posture precisely. Microscopically crimping of collagen fibres is visible in horse fascia, and histology reveals species variations between horse and dog fascia are related to the absence/presence of superficial adipose tissue and the amount of elastic fibres. Dysfunction of the Fascial System Good musculoskeletal function depends on pliability of the fascia, not just for movement but for sensory input, as the sensory nerves communicate between muscles and the central nervous system are found in fascia. When fascia is well-functioning, fibres slide and glide over one another allowing the fascia to move in all directions. When it becomes disorganised, strained or dehydrated, its ability to glide is impaired, it loses its flexibility leading to reduced range of motion in muscles and joints. Areas of tissue become thickened and tug on the fascial network further up the chain and when the body moves with tension fascia thickens and stiffens even further. The cause can be a natural consequence of trauma or injury, repetitive actions, inflammation, or immobility or when the body is forced to show movements its tissues are not prepared for. Fascia adapts to restricted patterns and spreads it throughout the horse’s entire system beginning the cycle of restriction producing more restriction. The result is fascia no longer has as much give contributing to overall musculoskeletal pain. In turn this leads to local and global problems in the body, signals about joint position and muscle coordination falter causing acute and chronic imbalance, myofascial imbalance, joint, venous and lymphatic dysfunction. This also accounts for the compensations that are seen in the body which can occur far away from the source; therefore restriction can be in one or several movement directions and will affect more than just that area. Fascia Training for Specific Disciplines Trainers of all equestrian disciplines are interested in finding a movement that is free and as effective as possible without compromising other areas of horse health. To achieve this, fascia needs to function well. Depending on how the horses’ body is used, demolition and building will happen as fascia adapts to these changes applied to it. Peak limb force is a major determinant of the strain placed on the musculoskeletal tissues of the limbs. The peak load that can be withstood by the limbs limits maximum speed. Every cell in the body is hooked into, and responds to the tensional environment of the fascia. The extra-cellular matrix of the fascia is capable of remodelling itself in a variety of ways, in response to direct signalling from the cells; injury; long-held mechanical forces; use patterns, gravity; and chemistry within the body. If mechanics are altered the cells can change their function. The intricacies of fascia remodelling are still being researched but knowledge of tensegrity (tension and integrity) and remodelling is the future basis for therapy and discipline specific training. Change the demand on the fascial system, by training for specific discpline or sport, and it responds to that new demand for optimal posture and function essential for the demands of the discipline. It also means small problems can be prevented from escalating into larger issues and to help the long-term consequences of injury. When thinking about discipline specific fascia training, fascial elasticity is also an important element to consider. Fascial elasticity is stored and returned quickly so is only a factor when the motion is cyclic and quickly repeated, such as galloping, but not when the repetitive cycle is too slow. Building in this elasticity requires putting demand on the tissues slowly. The fascial system responds better to variation than to a repetitive program. Evidence suggests that the fascial system is better trained by a wide variety of adjustments in angle, tempo, load, etc. Working in one track may be useful for muscles but is not beneficial for fascia. Loading the tissue one way means it will injure more easily when a movement out of its usual line occurs. This is vital to consider when thinking of a flat race horse where training is linear, with little if any cross training, variety is low and movement is highly repetitive. Exercises that focus repetitively on the same range or plane of motion cause fascia to become sticky and thick, limiting glide which causes some of the dysfunction previously discussed. This is also important to consider at the elite end of dressage where demand to get the precise technical movements faultless, such as piaffe for example, can mean some highly repetitive training. Not only that, the variation in forces of different movements change physiological demand, for example, in passage, there are higher vertical impulses than in collected trot, causing greater elevation of the centre of mass therefore greater ground force reactions. Forelimb and hind limb vertical force distribution determines the position of the centre of pressure. Horses are thought to adjust force magnitudes in order to control movements around the centre of mass the fascial systems proprioceptive and adaptive precision is thought to play a large role in this. Elite dressage horses may also not be getting the same multidisciplinary exercise they were at the lower levels. A logical training regime based on applicable, variable strategies providing different movement directions and exercises at each horse’s level will help fascia develop well and remain healthy. Seven myofascial lines have been found in the horse, whole body movements that engage these chains are the best way to train the fascial system and cross discipline training will help get the variation in movement required. According to Myers 2009 looking at human fascial training these methods include exercises of adaptive movement; due to the role of fascia in proprioception and kinaesthetics, proximal initiation; starting movements with a dynamic pre-stretch, initiation in the desired direction and letting the more distal parts of the body follow in sequence, like an elastic pendulum, however this is difficult to achieve with horse. Also surface tissue stimulation to enhance proprioception; rubbing and moving the skin and surface tissues to enhance fascial proprioception can be extremely effective. This is due to the multitude of sensory nerve endings, which may also help to communicate to the nervous system there is no longer need for tension in the area, also the basis of some fascial release techniques which aim to improve the slide and glide of the tissues, hydrating them through compressing and releasing. This pushing on fascia between bones, muscles, organs, and nerve fibres has been shown to free mobility more than passive stretching alone. Research shows that due to the influence of myofascial release on the nervous system, it largely helps with the baseline tone of muscles too. A well hydrated fascia network plays an enormous role in overall fitness too, so it is vital that the facial system is fully functional and well trained. Management and overall state of health also has a big effect on the fascia such as amount of turnout so the horse can get the chance to use its body freely, in many different ways, on different surfaces and terrain. Conclusion The effect of a healthy fascial system on the horses’ body as a whole has been shown to be highly relevant, and an important factor to consider when training horses’, be it for racing, show jumping, eventing, barrel racing or dressage. For example in flat racing good fascia health is required so the whole of the musculoskeletal system is working at maximum effectiveness to get the speed and stamina required. In the dressage horse the refinement and precision that comes from the sensory and proprioceptive capacities of the fascial system are of highest importance. A need to ensure the fascial system is not over looked, as it has been in the past, has been highlighted in this review. It is extremely important when choosing training methods to ensure fascia training is taken into account, consequently all the structures of the musculoskeletal system will be supported and enhanced by a well maintained fascial network in the course of the horse’s education, as well as helping refine the skills involved in each discipline and preventing injury. Developing better fascial training plans based on the demand of each individual equestrian sport can extend functional movement up the age scale to ensure career longevity future proofing the horse. More equine specific research relating to fascial response to specific training is required so more specific equine exercises can be developed.