Can We Use Information on the Mechanical Properties of Waxed Sand/Fibre, Sand/Fibre and Sand/Rubber Arena Surfaces to Help Understand Injury Prevention?

Recent research demonstrated that there is a link between arena surfaces and lameness in the dressage horse, that horses alter their gait on different surfaces and that cross‐training on different surfaces was protective (Murray et al . [Murray, R.C., 2010a],[Murray, R.C., 2010b]; Walker et al . [Walker, V.A., 2012]). However, there are minimal data on arena mechanical properties and how these could relate to injury. Aims To compare the mechanical properties of 3 common arena surface types. Methods A dual‐axis synthetic‐hoof drop hammer fitted with accelerometers and a 3‐axis load cell was used to test 49 arenas: waxed sand with fibre (WSF) (n = 16), un‐waxed sand with fibre (SF) (n = 19) and un‐waxed sand with rubber (SR) (n = 14). Ten different locations were tested on each arena. Maximum load and load rate (representing firmness), maximum vertical and horizontal accelerations (representing friction), shear angle, and hysteresis (representing elasticity), were compared between the 3 surfaces using an independent samples Student's t test. Results There were significant differences in firmness, friction and elasticity between all 3 surfaces, with WSF having the greatest values for all properties. When looking at the un‐waxed surfaces, adding fibre resulted in increased friction, decreased firmness and decreased elasticity compared with adding rubber (Table  ). Conclusions and practical significance The mechanical properties of the surface types are significantly different. These findings suggest that a horse's limbs may experience more rapid deceleration and higher impact on WSF, while on SF or SR a horse has more capacity to slide through the surface with less impact but experiences less energy return. This has implications in potential development of injury on different surfaces, and reinforces the requirement for proprioceptive training on varying surfaces prior to undertaking peak loading on a surface the horse has not trained on. Ethical animal research Not applicable. Sources of funding: Funding from World Horse Welfare, the Swedish‐Norwegian Foundation for Equine Research and UK Sport lottery funding for the BEF World Class Programme. Competing interests: None. Summary of the mean and standard deviation for maximum load and load rate, maximum vertical and horizontal accelerations, shear angle and hysteresis for waxed sand/fibre, sand/fibre and sand/rubber arena surfacesProperty Waxed sand with fibre Sand with fibre Sand with rubberMax load (kN) 13.35 ± 2.89 6.83 ± 4.09 9.88 ± 3.04 Max load rate (kN/sec) 406.75 ± 34.41 297.55 ± 110.18 382 ± 45.86 Max vertical acceleration (m/sec 2 ) 71.37 ± 27.48 37.54 ± 12.33 34.03 ± 15.92 Max horizontal acceleration (m/sec 2 ) 11.29 ± 10.44 5.67 ± 4.95 4.22 ± 3.95 Shear angle (radians) 0.285 ± 0.08 0.320 ± 0.11 0.320 ± 0.11 Hysteresis 0.135 ± 0.042 0.056 ± 0.036 0.085 ± 0.066