Effects of Footwear Choice amongst Field Hockey Participants on Factors Influencing Overuse Injuries

Abstract
Field hockey is a popular sport played worldwide. Due to the demands of the game, injuries are common, restricting participation. Injuries occur due to a single traumatic event or are due to repetitive loading. Injuries caused by repetitive loading, known as overuse injuries, have been linked to various measureable kinetic and kinematic variables. The magnitude, direction and distribution of the applied loads have all been identified as factors influencing the onset of an injury. Furthermore, footwear, surface and speed of locomotion have also been identified as factors which will influence injuries. Altering these variables could assist in reducing the prevalence of overuse injuries across a population of participants.
The initial study within this research investigated the magnitude and direction of applied ground reaction forces to the alignment of the tibia. Testing different insole surfaces, a rougher surface was found to increase proprioception, identified through a significant difference in the alignment of the tibia to the resultant ground reaction force vector. The next investigation used an adapted plantar pressure measuring device to record peak pressures between the uppers of the foot and shoes during various sports specific movements. Levels of peak pressures were found to match those under the feet. This method of assessment is therefore recommended for testing footwear designs in the future.
Whilst there is an established relationship between the Ground Reaction Force (GRF) and tibial acceleration, this study compared a variety of previously reported GRF characteristics such as loading rates, peak forces and time to peak forces, to tibial accelerations using a shank mounted accelerometer system developed for this research. This provided identification of key ground reaction force characteristics linked to impact shock, for assessment of the footwear.
This study then assessed a set of different footwear typically used by field hockey participants. The influence of these shoes on GRFs, and in–shoe pressure was investigated during running and jogging. These shoes along with a new prototype of running shoe designed to encourage forefoot running, were also assessed for their influence on impact shock measured directly using the shank mounted accelerometer system. A custom made computer program was employed to analyse the data. This program could be used in future research and clinical assessment.
The results of the footwear evaluation identified that moulded cleat designs with a lack of midsole cushioning exposed participants to injury causing loading of the musculoskeletal system and therefore were not recommended for use in field hockey participation. Furthermore, the prototype running shoes were adjudged to require pre-training and further assessment. The other shoes which included running, soccer and hockey specific footwear did not produce any significant differences across the population of participants. However it was found that individual assessment produced many differences between the shoes. These results demonstrated that the shoes can have a positive and negative effect for different individuals on kinetics linked to overuse injuries. It was concluded that individual assessment was needed for identification of the correct footwear choice.