Arena surfaces are subject to compaction, drainage issues, surface irregularities, and influences of climate and temperature. A surface that is too hard can lead to bone, joint, and hoof injuries. A surface that is too soft and yielding can lead to soft tissue injuries. An irregular surface can not only interfere with a horse’s performance due to tentativeness about the footing but also cause injury due to unexpected transition between hard and soft, lumpy and firm. The best way to ameliorate some of these concerns is to build a well-engineered arena.
From the Foundation Up
A research team at the Animal Health Trust (AHT) in Newmarket, U.K., has been studying the elements that make a riding arena durable and safe. The starting point for developing any arena is the foundation. “The main purpose of the foundation underneath the surface footing is to provide a stable base for the arena,” says Carolyne Tranquille, BSc, a research assistant at the AHT who has collaborated on this topic with senior orthopaedic advisor Rachel Murray, MA, VetMB, MS, PhD, MRCVS, Dipl. ACVS, ECVS, and others.
Tranquille notes that it is important to use the same foundation material beneath the entire arena for consistency; she cautions against using unstable bases such as crushed concrete, suggesting limestone or asphalt instead. Additionally, she recommends leveling the base or grading it to have a slight incline toward the center to assist with drainage. “These three factors—the material used, consistency of foundation material, and the effectiveness of drainage—affect how the top layers behave,” she says.
Drainage is particularly important for an outdoor arena that’s subject to changing weather. “Establishing a good drainage system with perforated pipes within the base layer ensures that the arena drains adequately and evenly; otherwise, areas that flood in heavy rain are likely to create an inconsistent surface for the horse to work on,” Tranquille says. “Use of a geotextile material placed between the base and the top layer is helpful to limit the amount of sand grains that could sift down and block the drainage system, thereby allowing water to wash away the surface.”
Once you’ve prepared your base foundation and drainage system, it’s time to apply the 3- to 6-inch top layer. “The top layer needs to provide the horse with a stable and even surface to work on,” Tranquille explains. “Ideally, the material used allows the hoof to slide forward on ground impact but also provides enough support to give the horse and rider confidence.”
She recommends choosing an appropriate surface type and depth for the riding you perform. “For example,” she says, “jumping and dressage pursuits need a more stable surface than reining.” For these former two disciplines she recommends using angular sand (as opposed to round sand), as the edges allow the grains to “grab” each other for surface stability.
“The addition of fiber and/or wax further increases the stability of the surface by increasing the binding between sand particles,” she continues. “And, amending with rubber is good for smoothing out the sand arena even more.”
The FEI (Fédération Equestre Internationale) has published a document titled “Equestrian Surfaces—A Guide” (fei.org/fei/about-fei/publications/fei-books) that explores various equestrian activities’ footing needs and arena surface development. It describes the characteristic of grip: “Surface grip is important when the hoof lands, when the horse turns, and during propulsion. It is important that the hoof can slide somewhat on landing, as that helps to absorb the impact. Meanwhile, the hoof should not slide too much, as this means the surface is slippery. When the horse pushes off (during movement on a straight line), the materials beneath the surface must withstand the push. The same principle holds on turns.”
Because different disciplines have different footing requirements, arena surfaces require the proper preparation for each sport. The FEI Guide authors note, for instance, that a dressage horse needs some traction to be able to perform advanced collected movements, yet he also needs sufficient “give” to be able to achieve speed and stretch at extended gaits. A jumping horse needs impact-dampening upon landing but still must have sufficient traction for takeoff. Horses competing in sports that demand tight turns (barrel racing, reining, some advanced dressage moves, jumping) need a firm surface to maintain footing, yet not so much that limbs stick and are overstressed because they are unable to rotate.
It can be difficult to account for each sport’s needs, especially when one arena plays host to several different disciplines. Often, facilities manage to strike a compromise and install a multipurpose surface that each discipline can use safely.
The Effects of Weather and Climate
“All arena surface types are suitable for use on indoor or outdoor arenas,” says Tranquille. Just remember that inside or out, weather significantly affects a surface’s consistency and behavior, and an inconsistent surface affects a horse’s stability and factors into fatigue. “Previous research on racing surfaces has shown that temperature and moisture content alter how the surface behaves, particularly with waxed surfaces and sand,” Tranquille says. “Consider the local weather patterns to ensure that the chosen surface material is suitable for the local climate.”
Many facility owners choose sand as their primary arena surface material, adding other materials to improve the footing based on temperature and moisture. Rubber or fiber amendments, for instance, reduce compaction. Rubber also helps retain moisture and so is a useful additive in drier climates, Tranquille says.
The FEI Guide authors explain that arena engineers often combine wax and polymer coatings with sand to improve a surface’s consistency and permeability, which reduces the effects of moisture. Drainage and maintenance also strongly affect how arena footing behaves in changing climates.
The Right Amount of Water
The FEI Guide authors stress that controlling water in and on an arena’s surface is at least as important as the surface material selection itself. Tranquille explains that evaporation rates differ between indoor and outdoor spaces and depending on sun or shade exposure.
For example, she says, “if the sand is too dry, the surface will ride deep and loose. In this case, increasing the moisture content increases the stability of the surface. Salt is sometimes used to prevent freezing; however, adding too much salt can harden the surface. Depending on the climate it may be more suitable to add rubber or wax to the sand to prevent freezing.” With good drainage, she adds, wax-coated sand requires less maintenance than other materials.
Dusty arena surfaces create a health hazard for horse and human alike when the footing material becomes airborne with horse activity. The dust can incite inflammatory airway disease in susceptible horses or asthma in people. “If a surface is dusty, this should be evenly watered on a regular basis,” Tranquille says. “Rubber or wax amendments to the sand help keep the surface moist, and this reduces dust levels in the atmosphere.”
Constant upkeep ensures an arena surface’s stability and consistency and helps it last longer. “Emerging evidence suggests that horses modify their gait patterns based on even small changes in surface preparation,” says the FEI Guide.
Tranquille suggests leveling, harrowing, or rolling the arena frequently using appropriate equipment and following the surface manufacturer’s guidelines. “Depending on the type of surface and riding pursuits, an arena is likely to benefit from daily maintenance if used by approximately 20 horses,” she says. For fewer horses, it might only be necessary to work the arena once or twice a week.
“The appropriate type of maintenance depends on the surface,” she continues. “For example, a waxed sand surface that becomes hard may need deep harrowing, or a sand surface that becomes deep may need watering and rolling. If a watering system is used it should dampen the entire surface evenly.”
Monitoring the surface for inconsistency is important for determining when it needs maintenance. Tranquille recommends looking for patchy, flooded areas in the arena that might develop after heavy rainfall. Water collection in patchy areas indicates a potential problem with the drainage system.
“There may also be patchy, hard areas suggesting that a different maintenance regimen should be used,” she says. “Owners should also keep an eye on the evenness of the surface—if it becomes too rolling, it could require professional leveling. Riders should also be aware if their horses are getting tired quickly or if the horse trips in specific locations in the arena, as for example in the corners—this often indicates that the surface is uneven or deep with a need for changing the maintenance regimen.”
Tranquille is currently heading up a project with the AHT’s Equine Orthopaedic Research Team, in collaboration with Lars Roepstorff, DVM, PhD, and his team at the Swedish University of Agricultural Sciences, examining different maintenance techniques’ effects on sand-based surface properties. The results will be available later this year.
In addition to managing an arena surface’s physical properties, Tranquille recommends weeding outdoor arenas regularly and removing manure daily to reduce surface contamination rate and, thereby, increase footing longevity. Manure and urine can degrade waxed, polymer, fibrous, or wood chip materials. Additionally, manure decreases grip and traction and, when dried and aerosolized, degrades air quality.
The FEI Guide includes a particularly compelling point for encouraging manure cleanup: “If every horse produces manure once during each session in the arena, the manure will have a volume of about 2 liters. With 50 horses a day using the arena and no mucking out, this means 100 liters of manure daily being mixed into the surface. After three years, 50% of the top layer will represent manure.” If you’re not mucking your frequently used arena daily, you might need to replace the top layer every three years.
The FEI Guide also advises against using an arena as a turnout area because a loose horse frolicking and rolling can cause the surface to become unlevel. Similarly, longeing horses increases compaction and unevenness in that location, thereby altering the surface’s consistency. Just as you shouldn’t always longe your horse in one specific space, you should vary your riding track away from the rail and move jumps around periodically to avoid compaction.
Every Arena is Different
Remember that arena surfaces at different competition venues vary signficantly. This range poses a challenge to keeping a horse sound and performing at his best.
“It is important to train on a variety of different surfaces, including those used at competition, to promote musculoskeletal health,” urges Tranquille. She also advises riders to not work their horses very hard or fast on a surface that they are not used to.
One might also wonder how different types of horseshoes and trims work mechanically on different arena surfaces. Researchers have investigated the effects of deceleration and vibration (when the foot hits the ground in a stride) of the shod versus unshod hoof, finding fewer impact forces in the barefoot horse. Long toes are known to delay breakover, increase tension on the deep digital flexor tendon (DDFT), and increase the depth of toe penetration into ground surfaces. Shoes with wider heels lessen ground penetration at the heels and reduce strain on the DDFT. These shoeing approaches might alter the hoof-ground interaction and limb loading patterns.
“Horses are shod to increase grip on a surface, so therefore you would expect a difference with the hoof-surface interaction between a barefoot and a shod horse,” Tranquille says. “However, this requires further investigation before conclusions can be made.”
As it turns out, arenas affect a horse’s athletic ability and longevity. The science of building an arena is well-studied, and you can use the available research results to design one that is appropriate for your horse’s needs. An excellent foundation, good drainage, and a consistent surface are just some of the essential components that make up a safe, durable arena design.