Brain injuries are one of the most common type of injuries sustained by riders in equestrian sports. The most common cause of brain injuries in equestrian sports are oblique impacts to a compliant surface;​ equestrian helmets are not currently designed to protect against such impacts. There is a paucity of research into the mechanics associated with these types of impacts;​ studying the impact mechanics can provide insight to reduce the risk of brain injury by improving helmet designs. The main objective of this thesis was to analyse real-world equestrian accidents and associated helmets in order to provide a unique set of primary data that can be used to characterise brain injuries and helmet performance in equestrian sports.

Real-world accidents in equestrian sports were investigated to examine the associated impact mechanics and helmet damage. Video analysis of head injury incidents found that all cases involved the head impacting turf or sand surfaces and that 30% of racing accidents involved secondary and tertiary impacts from either a horse kick, collision with a horse, or the rider being crushed or stomped on by the horse. These secondary and tertiary impacts all resulted in helmet damage, however, for the majority of fall incidents no helmet damage was found. These results raised the question of whether equestrian helmets provide adequate head protection against falls for riders? Concussive thresholds for equestrian sports were found to be within the range reported in the literature but represented a unique combination of head kinematics. These unique biomechanical aspects of concussion should be considered when developing new approaches to reduce the risk of brain injury in equestrian sports.

A parametric study was performed in order to examine the main effects and interactions of impact parameters on head kinematics and brain tissue response for falls in equestrian sports. Impact velocity and trajectory angle had the largest effect on head kinematics and brain tissue response. Impact surface compliance and impact location also influenced head kinematics and brain tissue response but were less influential than impact velocity and fall trajectory angle. Significant interactions such as those between fall trajectory angle and impact surface compliance were found to greatly influence head kinematics and brain tissue response.

The suitability of current and proposed equestrian helmet test methods to represent realistic equestrian falls was also assessed. Impacts representing the equestrian helmet standards and the proposed EN13097-11 standard were found to produce higher acceleration magnitudes and shorter durations compared to actual concussive reconstructions due to the use of a rigid anvil instead of one that was compliant.

Finally, the protective capacity of an equestrian helmet was assessed for impacts to turf. The helmet was found to offer little to no protection for linear impact falls as helmeted impacts resulted in minimal reduction in head kinematics and brain tissue response compared to unhelmeted impacts. For oblique falls, however, the use of a helmet significantly reduced rotational kinematics and brain tissue stress and strain, although the values commonly remained above the 50% risk of sustaining a concussion. This suggests that an opportunity exists to improve the protective capacity of equestrian helmets. The implementation of rotational attenuating technologies in equestrian helmets may reduce the occurrence of brain injury, as rotational acceleration has been found to be a significant predictor of concussion and was commonly reported as the best predictor of brain tissue response.