Scientific research quantifies the impact different pads have on the horse's performance
/![[Headline]Scientific research quantifies the impact different pads have on the horse’s performance [Standfirst]The use of pads under the saddle has been common for years, but now scientists are using dynamic testing technology to discover how well they really work [INTRO]In everyday yard situations where multiple horses use the same saddle, putting one or more pads under has been seen as a way of providing cushioning and comfort for the horse, or even relieving pain. However, there has never been any research in racehorses to demonstrate whether this reduces saddle pressures or provides comfort. Furthermore, there is limited scientific evidence to suggest which type of pad is most effective. A recent study suggests that, depending on the material and design, using a pad beneath the saddle might not always achieve the desired pressure-relieving effect. And using multiple ineffective pads under the saddle might not only be a waste of time and money, but it could potentially cause areas of high pressures, compromising the horse’s locomotor apparatus and affecting race performance. [CROSSHEAD] Material matters[FIGURE 1] caption:Peak pressure of more than 35kPa were recorded in two of the three pads. Peak pressure of >35 kPa can cause compression of the capillaries, leading to soft tissue and follicle damage (ischemia) which, in extreme or prolonged cases, results in white hairs, muscle atrophy, skin ulcerations and discomfort. A recent published study evaluated saddle pressure distribution in sports horses using pads made from sheepskin, viscose gel and a medical-grade closed-cell foam. When using a gel pad, the peak and mean pressures increased in the front region of the saddle in trot and canter. This is possibly due to the gel’s lack of ability to dissipate shear forces compared to wool or foam. Similar findings were seen in a pilot study of thoroughbreds galloping at half speed over ground. The same dynamic testing was used (see Technology & Anatomy panel) to compare the forces and peak pressures under polyfill pads, as well as viscose gel and medical-grade closed-cell foam. From the initial trials, the overall forces recorded were significantly higher than those seen in the sports horse study. This seems reasonable, given the difference in locomotion and speed (see Speed & Force panel). Preliminary findings show the forces were 75% lower, and peak pressures were 65% lower under the medical-grade closed-cell foam pad than those recorded under the gel pad. Interestingly the polyfill pad, which deforms to the touch, reduced the forces and peak pressures by 25% and 44% respectively compared to the viscose gel pad. The role of the pad is to act as a dampening layer between the horse and the saddle, reducing pressures and absorbing the dynamic forces which occur during locomotion.Based on findings from the sports horse study, and initial findings from the racehorse study, it appears that the medical-grade closed-cell foam pad is superior in its effectiveness at acting as a pressure-reducing layer between the saddle and the horse. [CROSSHEAD] Pressure to perform Reducing saddle pressures improves gallop locomotion. Horses will still perform when asked, despite areas of high pressures induced by the saddle and pad; but they develop a compensatory locomotor strategy in an attempt to alleviate any discomfort. To increase speed, a galloping horse will either increase stride frequency or increase stride length. Both mechanisms can be used, but the horse will have a natural preference. Published pressure studies have shown that stride length is increased when saddle pressures are reduced. Now, new research is underway quantifying whether a stride frequency approach, which has higher peak forces, could be a compensatory strategy in response to discomfort caused by pressure. Forces are influenced by speed and weight and are produced when the hoof comes in contact with the ground. At racing speeds of 38 mph, the hoof hits the ground approximately 150 times a minute. Stride frequency is an important consideration because a study has suggested that horses have around 100,000 gallop strides before the soft tissues fail. Therefore, any reduction in loading cycles (number of strides) could potentially help reduce injury risk. Harder, faster, longerEvery stride impacts the horse’s joints, causing wear and tear (see Speed & Force panel), so fewer longer strides is the preference for optimum training efficiency. Although horses have a naturally imprinted option, the pressure studies demonstrate that they switch between the two in response to certain extrinsic factors, such as high saddle pressure. Our task as trainers is to optimise the horse’s locomotor efficiency by removing any impediment that might force it to adopt the shorter-stride compensatory gait. We speculate that equipment which increases pressure (such as an unsuitable design of saddle, bridle, girth or saddle pad) will be counterproductive because it may encourage an increase in stride frequency and compromise natural locomotor efficiency. [CROSSHEAD] Contouring is key[FIGURE 2] caption: A saddle pad that is shaped to follow the contours of the back is able to maintain better spinal clearance under the saddle when galloping. In both studies, the saddle pads that were designed to follow the contour of the horse’s back and withers performed better than those that were flat with no shaping. Furthermore, pads with a midline seam connecting the two sides were able to maintain traction and position, providing spinal clearance even at speed. In contrast, pads that were flat without any contouring or with no central webbing seam were observed to slip in response to the horse’s movement, drawing down against the spine under the saddle. This was seen even when the pads were pulled up into the saddle channel before setting off. Quality vs quantityIn an attempt to improve comfort, it’s standard practice to use multiple pads under an exercise saddle. However, adding more shapeless padding can lead to instability and potentially saddle slip. This feeling of instability can encourage the jockey to overtighten the girth in an attempt to keep the saddle still. One study demonstrated a relationship between increased girth tension and a reduced run-to-fatigue time on a treadmill, indicating that girth tension can affect the breathing of the galloping horse. In addition, bulk under the saddle puts a feeling of distance between the horse and rider. This compromises the close contact feel and balance all jockeys strive to achieve and hinders the lowering of the jockey’s centre of mass relative to the horse. Age concernIt’s worth noting that the ability of a material to absorb pressure can be significantly compromised with use and washing, as well as changes in climate. As some materials age, they degrade and lose any initial shock-absorbing qualities. For example, wool loses its ‘crimp’ over time and becomes less effective, so a well-used wool pad may not absorb as much pressure as a new one. The medical-grade closed-cell foam used in the saddle pad studies was developed to prevent capillary damage in bed-ridden hospital patients and the pressure relieving properties are not affected by extremes of weather or machine washing. Saddle systemIt is becoming clear that the saddle, pad and girth operate best when they are viewed as a complete system. When choosing a pad, it’s worth bearing in mind that these pressure studies were carried out under correctly fitted saddles with wide channels and ample spinal clearance. The benefits of a pressure-relieving pad are diminished by a badly fitting or poorly designed saddle with a narrow channel and limited spinal clearance. Likewise, trainers who are experiencing the performance gains associated with advances in saddle design will not reap the full benefits of a pressure-relieving saddle if the fit and effectiveness are compromised by poorly performing pads underneath. [PANEL] Speed & force [FIGURE 3] caption: The hoof exerts a force against the ground, and the ground exerts a force against the hoof, which is transferred through the muscles and tissues of the forelimb. In gallop, the forelimbs have to support two-and-a-half times the horse’s body weight with every motion cycle (stride). In each motion cycle, a fast-moving front foot interacts with the stationary ground and, as the hoof comes to an abrupt halt, the forelimb has to absorb these forces. The forces are transmitted through the soft tissues and muscles to the thoracic vertebrae in the region where the saddle and jockey are positioned. These thoracic vertebrae in front of T16 (the anticlinal vertebra) are responsible for force transmission from the forelimbs, head and neck. The horse’s back does not just have to deal with the large forces from the forelimbs (and hindlimbs) but also the dynamic forces of the jockey, which can be in excess of two-and-a-half times the jockey’s body weight. As speed increases, so do pressures beneath the saddle and pad. There’s a 5% pressure increase when the walk speed rises by 10%, and in trot it goes up to 14%. As the racehorse is travelling at a faster pace the forces involved are inevitably increased and, at gallop with the jockey ‘up in his pedals’, approximately 80% of his weight is focused on the front part of the saddle—the T10-T13 region (see Technology & Anatomy panel). If the saddle pad draws down along the spine during locomotion and creates restrictive pressure, this will interfere with muscle activation and force transmission, potentially causing the horse to adopt the compensatory short-stride gait.The horse will not only need more strides to cover the same distance, but it will also experience more forelimb loading every stride due to the increased speed of each cycle.Studies are ongoing into the long-term impact of this extra limb loading, but we speculate it will potentially result in poor performance and increased risk of injury.[END PANEL] [ PANEL] Stability in Motion[FIGURES 4a,b,c caption: The three axes of rotation]The spine rotates in three directions, providing stability, forcing transmission and generating power efficiently. Lateral bending – left to right Flexion-extension – up and down Axial rotation – rolling one side to the other For optimum locomotor efficiency, the vertebral column needs to be dynamically stable. Stability is the combination of strength and suppleness; it isn’t stiffness. The muscles in the back and neck must be strong so they can support the spine but flexible enough to allow the necessary range of movement and transmission of the dynamic forces required during locomotion.Studies have shown that when the saddle and rider are stable and symmetrical, the horse’s back can stabilise through the cranial thoracic spine at T13 (see Technology & Anatomy), allowing the efficient transfer of forces from the hindlimb.A saddle pad that is causing pressure is likely to compromise this dynamic stability. From a preliminary study, it appears that high pressures are associated with increased spinal instability. This instability is likely to cause the horse to seek a compensatory locomotor strategy and adopt a posture where the back is stiffened. Previous research has shown that back function and gallop kinematics are compromised by a stiffened spine.[END PANEL] [PANEL] Technology & Anatomy[FIGURE 5] caption: Pressure mapping and 3D motion capture are used to quantify the effects of saddle pads on performance at gallop on the track. Thanks to extensive research, scientists now have a greater understanding of the importance of the area around the 10th-13th thoracic vertebrae (T10- T13). This is the location of a high concentration of muscle activity related to posture and movement. Repeated studies have demonstrated how pressure at T10-T13 compromises the locomotor apparatus of the horse and consequently performance. Relieving pressure here affects the mechanics of the whole back, allowing the transfer of propulsive forces from the hindlimb, creating increased power and longer stride length. Testing equipmentResearch teams employ pressure mapping (using a mat with 128 sensor cells on each side of the spine) and 3D gait analysis (using Inertial measuring units) to show precisely how changes in pressure affect spinal movement. The measuring units (IMUs) quantify flexion-extension, axial rotation and lateral bending. The combination of these state-of-the-art measuring systems allows researchers to prove that relieving pressure has a direct effect on spinal kinematics. Long-term trials using pressure testing and gait analysis have demonstrated that back discomfort associated with pressure can affect the development of the horse’s posture, gallop stride and potentially long-term back health. [END BOX OUT] FURTHER READINGR Murray, Journal Equine Vet Science 2019 81 102795 K von Peinen, Vet Journal 2010 538 650-3 S Latif, Equine Vet Journal 2010, 42 630-6 R MacKechnie-Guire, Journal of Equine Veterinary Science 2020ML Peterson, Racing Surfaces white paper, http://www.racingsurfaces.org/bulletins 2012](https://images.squarespace-cdn.com/content/v1/517636f8e4b0cb4f8c8697ba/1619171002004-MBXCIWLV6YDQRJDIHBBU/OPENING+SHOT+%281%29.jpg)
By Dr. Russell Mackechnie-Guire
The use of pads under the saddle has been common for years, but now scientists are using dynamic
testing technology to discover how well they really work.
In everyday yard situations where multiple horses use the same saddle, putting one or more pads under the saddle has been seen as a way of providing cushioning and comfort for the horse, or even relieving pain.
However, there has never been any research in racehorses to demonstrate whether this reduces saddle pressures or provides comfort. Furthermore, there is limited scientific evidence to suggest which type of pad is most effective. A recent study suggests that, depending on the material and design, using a pad beneath the saddle might not always achieve the desired pressure-relieving effect. And using multiple ineffective pads under the saddle might not only be a waste of time and money, but it could potentially cause areas of high pressures, compromising the horse’s locomotor apparatus and affecting race performance.
MATERIAL MATTERS
Peak pressure of >35 kPa can cause compression of the capillaries, leading to soft tissue and follicle damage (ischemia) which, in extreme or prolonged cases, results in white hairs, muscle atrophy, skin ulcerations and discomfort. A recent published study evaluated saddle pressure distribution in sports horses using pads made from sheepskin, viscose gel and a medical-grade closed-cell foam. When using a gel pad, the peak and mean pressures increased in the front region of the saddle in trot and canter. This is possibly due to the gel’s lack of ability to dissipate shear forces compared to wool or foam. Similar findings were seen in a pilot study of Thoroughbreds galloping at half speed over ground. The same dynamic testing was used (see Technology & Anatomy section) to compare the forces and peak pressures under polyfill pads, as well as viscose gel and medical-grade closed-cell foam. From the initial trials, the overall forces recorded were significantly higher than those seen in the sports horse study. This seems reasonable, given the difference in locomotion and speed (see Speed & Force section). Preliminary findings show the forces were 75% lower, and peak pressures were 65% lower under the medical- grade closed-cell foam pad than those recorded under the gel pad. Interestingly the polyfill pad, which deforms to the touch, reduced the forces and peak pressures by 25% and 44% respectively compared to the viscose gel pad. The role of the pad is to act as a dampening layer between the horse and the saddle, reducing pressures and absorbing the dynamic forces which occur during locomotion. Based on findings from the sports horse study, and initial findings from the racehorse study, it appears that the medical-grade closed-cell foam pad is superior in its effectiveness at acting as a pressure-reducing layer between the saddle and the horse.
PRESSURE TO PERFORM
Reducing saddle pressures improves gallop locomotion. Horses will still perform when asked, despite areas of high pressures induced by the saddle and pad; but they develop a compensatory locomotor strategy in an attempt to alleviate any discomfort. To increase speed, a galloping horse will either increase stride frequency or increase stride length. Both mechanisms can be used, but the horse will have a natural preference. Published pressure studies have shown that stride length is increased when saddle pressures are reduced. Now, new research is underway quantifying whether a stride frequency approach, which has higher peak forces, could be a compensatory strategy in response to discomfort caused by pressure. Forces are influenced by speed and weight and are produced when the hoof comes in contact with the ground. At racing speeds of 38 mph, the hoof hits the ground approximately 150 times a minute. Stride frequency is an important consideration because a study has suggested that horses have around 100,000 gallop strides before the soft tissues fail. Therefore, any reduction in loading cycles (number of strides) could potentially help reduce injury risk.
• Harder, faster, longer
Every stride impacts the horse’s joints, causing wear and tear (see Speed & Force section), so fewer longer strides is the preference for optimum training efficiency. Although horses have a naturally imprinted option, the pressure studies demonstrate that they switch between the two in response to certain extrinsic factors, such as high saddle pressure.
Our task as trainers is to optimize the horse’s locomotor efficiency by removing any impediment that might force it to adopt the shorter-stride compensatory gait. We speculate that equipment which increases pressure (such as an unsuitable design of saddle, bridle, girth or saddle pad) will be counterproductive because it may encourage an increase in stride frequency and compromise natural locomotor efficiency.
CONTOURING IS KEY
In both studies, the saddle pads that were designed to follow the contour of the horse’s back and withers performed better than those that were flat with no shaping. …
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![[opening image]Photo credit North Lodge Equine[HEADLINE]Scientists discover performance inhibiting spinal pressure under rollers[STANDFIRST]Reducing pressure under the saddle, bridle and girth has been found to significantly improve performance, and now the roller has been scientifically tested[INTRO][Fig 1 – caption: A modified roller that removes pressure will allow the back to function without restriction.]Lost training days, treatment and medication for back problems are time consuming and costly, so optimising equine spinal health from early on is an essential consideration in improving equine health and welfare. When a young horse is started, one of its first experiences is to have tack on its back, initially a lungeing roller. The roller, a seemingly harmless piece of equipment and its effect on the horse, has previously been overlooked. However, it has now come under scientific scrutiny by the same research team that investigated the impact of pressure distribution under the saddle, bridle and girth on equine health and performance.Their recent study used high-tech pressure mapping to examine the pressures exerted on the horse’s back during lungeing (see technology panel). Localised areas of high pressures were consistently recorded under the roller on the midline of the horse’s back directly over the spinous processes in the region of the 10th and 12th thoracic vertebrae (T10-T12, see anatomy panel).High pressure directly in this region, as seen under a conventional roller, is likely to cause the horse to seek a compensatory locomotor strategy and adopt a posture where the back is stiffened and hollowed, resulting in an extended spine. Previous research has shown that back function and gallop kinematics are compromised by a stiffened spine.Studies have demonstrated that pressure-relieving modifications in a saddle result in increased stride length and hip flexion, along with a greater femur-to-vertical angle (indicating that the hindleg is being brought forward more as the horse gallops). Reducing saddle pressures leads to a marked improvement in the horse’s locomotion, allowing it to gallop more efficiently.The roller is positioned over the part of the back where the front half of the saddle sits; by applying these principles, modifying the roller to remove pressure would allow unhindered back function.The equine back is an essential component of the locomotor apparatus, transferring biomechanical forces from the hindlimb. So, a modified roller will not only result in improved locomotion and performance but will also have long-term spinal health benefits.[CROSSHEAD] Strong startIn racing, where lungeing is primarily used prior to backing, what we do to and the equipment we use on the young horses in the preparatory stages are likely to have a significant impact on the development of the horse’s posture, back health and locomotion.If a young horse begins the training process of being lunged with a roller that exerts pressure directly on the spine at T10-T12, it will develop a strategy to compensate for the discomfort. Then, as the horse progresses to a saddle—which similarly exerts high pressure in the same area—it is inevitable that this will have an effect on the locomotor system. The horse’s athletic performance will be significantly compromised before it even gets on the track.Innovative pressure-relieving modifications in tack design have demonstrated improved locomotion when pressure is reduced. Identifying and replacing any equipment that has limiting effects on locomotion or development could have long-term benefits for the longevity and performance of the horse. This applies particularly to the lungeing roller as it is the first piece of tack a youngster has on its back. It is essential that the horse does not develop a locomotor strategy to compensate at this stage.[CROSSHEAD] Under pressure[fig 2 caption: Pressure mapping during lungeingConventional roller - 35kPa pressure directly on the spine at T10Conventional roller & side reins - pressure consistent at T10 but increases at T11 and T12 to 45kPaNew roller design, even with side reins - all pressure is removed from the spine]In a recent study, horses were lunged on a 20-metre circle on both reins in trot and canter wearing a roller fitted with pads. In canter, peak pressures were seen each time the inside forelimb was in stance (on the ground). In trot, pressure peaks occurred each time a forelimb was in stance phase.Given that the horse is experiencing high pressures under the roller directly on the spine in the region of T10-T12 in every repeated motion cycle (stride), it is inevitable that a compensation strategy will develop.When trotting and cantering with no attachments, such as side reins or training aids, peak pressures under the centre of the roller were found to be similar to those seen under the saddle with a rider on board. Studies have shown pressures over 30kPa can cause back discomfort. In this study, researchers measured pressures up to 35kPa directly on the midline of the horse’s spine, in every stride, with just a roller and pad.With side reins attached, the location of the peak pressure was brought further towards the front edge of the roller. Essentially, the pull of the side reins caused a ridge of pressure under the front half of the roller, and the readings increased to 45kPa.[CROSSHEAD] Compensation costsCompensatory gait strategies lead to asymmetric forces which have a negative effect on limb kinematics (movement). The consideration here is that the horse is experiencing these locomotor compromises before the back has been conditioned to manage the increased forces, and before a jockey has even sat on its back.It remains to be shown whether the compensatory gait and asymmetric forces caused by early roller pressure manifest as lameness or loss of performance later on. There is a coexisting relationship between back problems and limb lameness, but evidence is still being gathered as to which one comes first. Researchers are investigating to what extent loss of performance and lameness issues might be traced back to these ‘training and backing’ experiences. It is therefore essential that young horses are started with correctly fitting equipment to limit any long-term effect.[CROSSHEAD] Lungeing for rehabIn addition to the backing process, lungeing also occurs during other influential periods of a horse’s life, including rehabilitation after surgery. Post-operative recommendations for kissing spines can often include lunge work with training aids to induce spinal flexion and opening up of dorsal spinous processes. In these cases, if horses are being rehabilitated wearing a roller which creates high pressure on the very area it is supposed to be improving, it is likely that the benefits of using any training aid will be diluted.It is also likely that lungeing for rehabilitation using a roller which creates high pressures will have a detrimental effect on any veterinary or physiotherapy programme.[CROSSHEAD] Assess all areasThanks to advances in recent research developments and design, it is now possible to take a more holistic view and examine the whole horse when looking at training tack. Of course, there are benefits from making modifications to individual items, but maximum gains are achieved when the whole locomotor apparatus can function without restriction.For example, girth pressure has been the subject of extensive investigation, and a modified girth design which relieves peak pressures behind the elbow has been proven to significantly improve gallop kinematics. Combining a pressure-relieving lungeing roller with a girth designed to de-restrict the musculature will maximise locomotor benefits.Bridle design has also been shown to have a significant impact on the horse’s locomotor apparatus. When bridle pressure is reduced and stability is improved by using a correctly-fitted noseband, gait analysis shows an increase in forelimb extension and a greater range of hindlimb motion. Using a modified bridle when lungeing will enhance the benefits afforded by the roller and girth. Each modification is a step towards improving comfort, which will improve athletic performance.[BOX OUT] Modified roller design[fig 3 caption A new design of roller, based on a tree similar to that used in a saddle, alleviates pressures directly on the midline of the back by ensuring clearance of the spinal processes is maintained while the horse is moving][fig 4 – each image has a text annotation]High pressure was recorded directly on the spine (T10-T12) under conventional rollers (with pads) used by the majority of yards. Even when used with pads, these rollers still draw down on to the spine when the horse is in motion because they have no integral support to ensure that clearance of the spinous processes is maintained.Reins and ringsUsually, side reins are attached around one or both of the roller’s ‘girth straps’. The lungeing study demonstrated that this pulls the front edge of the roller forward, increasing pressures on the horse’s back. A roller with ring attachments tends to stay parallel to the horse’s back during motion—the ring provides articulation between the roller and the side rein, helping maintain stability.An added benefit of a design with extra rings is that it enables the roller to be used throughout the backing process. For example, stirrups can easily be attached to prepare the horse for the saddle.[END BOX OUT][BOX OUT – Spinal anatomy][fig 5]The area around the thoracic vertebrae T10-T13 (the base of the withers) is the location of a high concentration of muscle activity related to posture and movement.The Longissimus dorsi (m. longissimus dorsi) is a stabilizing muscle that’s most active at T12, and spinal stability is essential for the galloping thoroughbred. This is because, in gallop, the forelimbs have to support two-and-a-half times the horse’s body weight with every stride. In addition, the cranial thoracic vertebra (where the saddle, roller or jockey is positioned) are responsible for force transfer from the forelimbs, head and neck. It’s the back that has to manage these high forces.The horse has no collarbone, and the forelimbs are attached to the trunk by the thoracic sling musculature. Some of the most influential and important thoracic sling muscles attach to the spine, so it’s easy to appreciate why spinal health is critically important. Any compromises in this area at any stage of the horse’s career will impact on performance.When compromises such as high pressures occur, the horse adopts a compensating strategy. It will still perform but will develop a gait that alleviates discomfort.Anatomical structures or locomotion patterns that have been affected by a compensatory gait will be disadvantaged in terms of performance and, potentially, more susceptible to increased risk of injury.[END BOX OUT][BOX OUT] PRESSURE TESTING[fig 6]Pliance is the industry-standard method of measuring pressure on the horse’s body. It has been utilised extensively in research under saddles, and it can operate in all gaits, including gallop and jumping.A large mat with 128 individual pressure sensor cells on each side of the spine is usually positioned over the back, under the saddle. In this study, the mat was positioned transversely across the back, with sensors able to measure pressure directly on the spine.Initially the results are displayed as a moving colour-coded image, with areas of peak pressure showing as pink and red. Data regarding peak pressures, maximum force and mean force is also available, and is extracted and processed for statistical analysis.[END BOX OUT]Further readingEuropean Trainer Magazine, January-March 2020European Trainer Magazine, April-June 2020European Trainer Magazine, July-September 2020R Mackechnie-Guire, Local back pressure caused by a training roller during lungeing with and without a Pessoa training aid, Journal of Equine Veterinary Science 67 (2018)R Coomer, A controlled study evaluating a novel surgical treatment for kissing spines in standing sedated horses, Veterinary Surgery 41 (2012)K Von Pienen, Relationship between saddle pressure measurements and clinical signs of saddle soreness at the withersF Henson, Equine Neck and Back Pathology, Wiley Blackwell (2009)](https://images.squarespace-cdn.com/content/v1/517636f8e4b0cb4f8c8697ba/1603538376744-J61CHNNHPXPO0H3DBRJT/Screenshot+2020-10-24+at+12.19.17.png)
