Determining impact intensities in contact sports

Most sports Personal Protective Equipment (PPE) consist of varying levels of foam – more foam equals more protection. This has led to bulky, cumbersome PPE which restricts user movement. However, before existing PPE can be modified, their performance must be assessed and a baseline for necessary protection must be explicitly determined. This is a major limitation since current techniques for assessing PPE performance and impact intensity measurements from sport have used surrogate anvils and impactors which were not validated for the sports-related impact they tried to replicate. Through a series of independent studies, a better understanding of human impact response in sporting impacts was sought. This included investigating methods for improving the measurement of impact intensities in sports and the assessment of PPE performance. Human impact response revealed that tensed muscle led to a significant increase in impact force but was associated with less perceived discomfort. At low impact intensities common to sport, the increased local stiffness helped to dissipate impact energy and reduce soft tissue compression. As previous anvils omitted this soft tissue response, modifications were made to a martial arts dummy, BOBXL, to increase its biofidelity. This anvil was validated using in vivo kicks and an impact force – impact velocity relationship. Using this validated anvil, existing methods of assessing PPE performance were evaluated. Current methods were found to create artificially comparable levels of force but did so by using an incorrect effective mass and impact velocity. In all tests, PPE performance was found to depend on weight providing evidence of the ‘more protection, more foam’ concept. As it is impractical to use in vivo kicks to assess PPE performance, kick kinematics were investigated to assess its variability in terms of the impact force – impact velocity relationship and its accuracy. This aided in the development of a mechanical kicking robot which could more properly assess PPE performance. This research was applied to the design of form-fitting, impact-mitigating sports PPE with the capability for integrated technology. Proposed amendments to the current methods of assessing PPE will help to develop better testing and better performing PPE in the future.