Properties of equestrian surfaces such as hardness, traction and resistance to penetration may change during competition. A surface itself has a direct impact upon an athlete since it is the primary point of contact, therefore any changes which occur could affect performance or the possibility of injury. At present management regimes which are aimed at reducing such risks are based upon anecdotal evidence from site managers and surface construction companies. The aim of the present study was to validate a suite of mechanical tests on sand, fibre, rubber and wax equestrian surface, which were then used to quantify the effects of a preliminary, unaffiliated dressage competition on the hardness, traction and resistance to penetration of the surface. In addition laboratory analysis was used to determine surface components and the effects of temperature on the surface. The mechanical properties that were measured were hardness, using a Clegg Impact tester, traction, using a torque wrench and penetrability, using a penetrometer. Each piece of equipment was tested on a prepared, synthetic equestrian surface at Myerscough International Arena, in order to determine the method of use which produced results with least variability. The results of this work suggested that the 2.25kg Clegg hammer, the torque wrench using a horse shoe plate, under a weight of 30kg, and the Longchamp penetrometer, should be used. It was also found that five repetitions should be made in a single position with each piece of equipment. The equipment was used to test a 20m x 40m dressage arena, before and after six preliminary, unaffiliated dressage competitions, held between January and June 2009. Thirty two positions were tested within the arena, which were split into two sets of 16. The first set of 16 were positioned 7.5m apart around the outside (track) area, and the second set of 16 were randomly positioned in the central area using a stratified random sampling method. In addition, temperature data was recorded at each of the competitions. The results showed that the hardness of the surface increased significantly (P<0.05) after a preliminary, unaffiliated dressage competition. The changes in the traction of the surface varied with each competition, all changes were found to be significant (P<0.05). The results regarding the penetrability of the surface were affected by the presence of the fibres in the surface, and therefore were deemed unreliable in this instance. There were significant changes to the surface over the period of six months, hardness decreased from 80±0.9G to 62±0.8G (P<0.001), traction decreased from 21.5±0.1Nm to 16.9±0.1Nm (P<0.001) and total penetration depth increased from 1.9±0.03cm to 3.6±0.06cm (P<0.001). There were significant differences found between the mechanical properties of the track and the central areas (P<0.05). The findings show that the mechanical properties of the surface changed significantly over a dressage competition. Short term changes could leave late competitors working on a different surface to early competitors, thus the running order of an event could affect the results. This highlights a need for further examination of the interrelationship between performance and surface variability. Significant long term changes were evident in hardness, traction and penetration, highlighting the need for a management protocol informed by surface testing in order to provide a surface with consistent properties.