In 2014, The Swedish Equestrian Federation sponsored and co-produced with the Swedish University of Agricultural Sciences an extensive guide on equestrian surfaces. Presented here is Equestology's summary of this comprehensive 129 page document.
Many equestrians discuss and want an answer to what is "the best" riding surface. However, several factors should be used to decide on the best materials and construction for your arena.
Furthermore similar surface properties can be obtained with different materials.
It is the properties of the surface rather than the material it is composed of that affects the horse.
The properties of the same arena will change based on wear, maintenance and environmental factors.
The risk of injury on a surface is to a large extent determined by how it is used. The intensity, speed, duration, frequency and type of work are all as important as the properties.
A riding surface is only as good as its maintenance programme.
Water is one of the most important influences on the properties of an arena surface.
THE INTERACTION BETWEEN THE HOOF AND THE ARENA SURFACE:
The leg and hoof of the horse have to with stand great forces the the hoof hits the ground (hoof landing /touchdown), when it carries the full weight of the horse (support phase) as well as during turns and when increasing and decreasing speed. Several factors influence the force and load on the leg: the properties of the surface, shoeing, the conformation of the horse, gait, speed and direction.
A stride is defined fro the time when the hoof touches the ground until the next time it touches the ground in the subsequent stride. The stride is divided into the support phase and the swing phase.
Hoof landing and breaking (touchdown)
As the hoof lands there is a pride braking effect during which the hoof slides forward and downward onto the surface. The impact and braking forces transmit shockwaves and vibrations through the hoof, joints and bones in the lower part of the leg. The harder the surface and the more grip it has, the more shockwaves and vibrations the leg experiences. the risk of injury in this phase mainly affects the hoof and distal part of the leg. there fore there should be a certain slide in the surface to avoid heavy loads on the lower part of the leg.
Support Phase (Full contact and load) The support phase begins when the hoof stops sliding/braking and is in full contact with the ground. The hoof and leg are loaded from above by the full weight of the horse. The risk of injury in this phase mainly affects the tendons, ligaments joints and bone.
At the end of the support phase the horse in effect braces the hoof against the ground, propelling the leg forward. At that moment surface grip (friction dn shear strength)his important fro the hoof to get sufficient traction. This final phase before the hoof leaves the ground is called rollover(breaker). The hoof lifts at the heels first and rolls over the toe. This phase loads the ligaments, the hoof wall and the tip of the coffin bone and stretches the superficial digital flexor tendon.
ARENAS, THEIR FUNCTION AND PROPERTIES
How do you characterise a riding surface. It is the properties of a riding surface that affect the horse this paper came up with six functional properties of riding arenas which helps to define and evaluate riding surface properties.
Impact Firmness- describes the mechanical shock experienced by the horse when the hoof first hits the ground.
Cushioning- describes how the surface is able to dampen and reduce the maximum force when the horse puts its full weight on the leg during the support phase. A surface that provides good cushioning can reduce the stress and strain on the horse's leg when the hoof is in full contact with the ground.
Responsiveness- Describes how active the surface feels to the horse.
Grip- affects how much the horse's hoof slides during landing, turning and pushing off. Grip is determined by both surface friction and and how well the top layer and the materials beneath interlock and hold the surface together to provide traction. Surface grip is important when the hoof lands, when the horse turns and during propulsion. The friction on the surface affects the hoof landing It is important that the hoof is able to slide a little 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, the materials beneath the surface must withstand the push.
Uniformity and consistency- Uniformity describes how much the characteristics vary across a whole area. A surface can be even and look level but the impact firmness, cushioning and grip can change. If the variations within the arena are greater and more frequent the horse can find it difficult to adapt, and is more likely to trip or even be injured. Unlevel surfaces are also likely to vary in their properties. For this reason activities need to be varied across the arena especially lunging and riding along the track.
Traditionally jumping and dressage riders have slightly different expectations and demands of a surface. Experience from international events including championships such as the Olympics or World Cup Finals with Dressage and jumping held in parallel show that the two disciplines can share the same arena. Jumping riders expect surface with more impact hardness which can be achieved mainly through rolling the surface and increasing moisture content by more watering. Dressage riders typically want a looser, softer top layer. This can be achieved by harrowing the superficial layer.
Sand: The major ingredient in most riding arenas is sand which consists of varying proportions of sand, air and water. The sand may either be natural sand (which tends to consist of grains of early round polished sand grains) or crushed from rock (with particles which are more angular) The shape of the individual sand grains greatly determines the abrasiveness, the durability, the grip, and the compactability of the arena surface. Natural sand tends to be more durable and less prone to compaction, but provides less grip.
Washed sand is sand in which the smallest particles have been washed away. if used on its own it tends to provide less traction/grip as all the grains are approximately the same size.
Water: Water is the single most important factor that influences the properties of an arena. Compare walking or running on a beach; too much water and the sand is too boggy, too little water and the sand is too loose and deep. Somewhere in between the sand is ideal for running on because of its impact firmness (shock absorption), cushioning (force reduction), responsiveness (springyness) grip (ability to withstand the pressure of your foot as you push off from the ground with each stride) as well as it's uniformity and consistency. Water can either be applied from above the ground via various watering systems or by subsurface watering with "ebb and flood systems" which have been developed in continental Europe, are becoming increasingly popular.
Fibre and textiles: Fibre and textiles increase the binding between sand particles thereby improving the grip and friction. Like sand there is much variation the textiles available so it is important to consider the size of the particles, its UV stability and the presence of glues/rubber as in recycled carpet based materials. The more fibre used the more grip imparted and the better the arena will be suited to higher speeds. Indoor arenas are best constructed with fine sands which adhere better to fibre. silica sand is ideal as it is more durable. Outdoor arenas require a coarser sand to help facilitate drainage. for a fibre sand mix to function correctly, the sand and fibre must be mixed property and watered appropriately. If the sand is allowed to dry out the fibres can accumulate on the surface of the arena. A well maintained fibre and sand arena should last for 20 years. Considerations about final disposal need to be made.
Wood chips: a renewable resource which improves responsiveness and elasticity of a sand arena. Has a short lifespan than fibre/sand but is easily disposed of. because it is naturally biodegradable it can get slippery and will need regular top ups. diligent removal of manure will reduce slipperiness.
Wax: Requires less watering, protects vertical drainage, and is easily installed and maintained. However it can be difficult to dispose of, is more sensitive to environmental temperatures ( soft and loose in summer, prone to compaction in cold weather).
Manure: uncollected manure accumulates quickly on an arena quickly becoming an ingredient in itself and having a detrimental effect on the arenas properties. on a wood sand arena the manure quickly mixes with the wood and forms a compost like material which can make the surface slippery. On a waxed sand arena horse urine and manure alters the properties of the wax, by causing it to dry out. If manure is left on a surface it can also affect air quality for horses and humans. Leaf litter can also have a similar effect to manure. For this reason all organic matter must be diligently collected and turning horses out on an arena is not recommended.
An arena always has a base and a top layer depending on the composition of the top, the design of the arena and base layer there can be a middle layer. The base layer should be sufficiently durable to remain uniform during use and maintenance of the surface. the surface of the base layer should resist damage with particular consideration for areas such as jumping landing and the use of maintenance equipment.In dry climates and indoors clay can be used to keep a surface from drying too quickly. in wetter areas the base layer is important in promoting drainage.
The middle layer where used is designed have a stabilising and levelling effect and to provide good dampening of the maximum load of the horse.
The top layer should provide the horse with an even and stable surface on which to work. The surface should allow the hoof a certain amount of glide at touchdown yet still provide enough grip to maintain the confidence of the horse and rider. The top layer should reduce the shock at impact and the material should move just enough so that it can gather under the hoof when the horse moves on a circle and thereby provide support to the whole hoof when the horse angles through a turn.
Water control is important both to help keep the surface moist and to allow drainage. The control of water is equally as important as the selection of the material for the surface.
MAINTENANCE AND RENOVATIONS
No arena is better than the maintenance that it gets. The aims of a maintenance program is to :
- Keep an even distribution of the top layer across the whole arena
- Maintain the mixture of different materials in the top layer so that the top layer maintains its intended properties
- Prevent compaction of the top layer ( harrowing and dragging, alternating between driving clockwise and anti-clockwise)
- Maintain correct and consistent moisture
- Protect the base layer
- Keep the arena free from manure and other organic material such as leaf litter and weeds.
Maintenance free arenas do not exist. A maintenance program need to be designed with the climatic an use patterns in mind. With suitable machinery for regular and frequent harrowing, a suitable application of moisture, diligent collection of organic litter (leaves, manure etc) and annual renovation, an arena surface should last up to 20 years.
Reference: Hernlund, E., Lönnell, C., Roepstorff, L., Lundholm, M., Bergström, L., Andersson, A-M., Carlsson, B., Fogelberg, F., Krügel, F., Söderberg, M., Hoberg, O., Clayton, H., Egenvall, E., Hobbs, S-J., Mahaffey, C., Martin, J., Murray, R., Northrop, A., Peterson, M., Thomason, J., Tranquille, C. & Walker, V. 2014. Equestrian Surfaces – A Guide.