EVA mouthguards: how thick should they be?

A major consideration in the performance of mouthguards is their ability to absorb energy and reduce transmitted forces when impacted. This is especially important to participants in contact sports such as hockey or football. The thickness of mouthguard materials is directly related to energy absorption and inversely related to transmitted forces when impacted. However, wearer comfort is also an important factor in their use. Thicker mouthguards are not user-friendly. While thickness of material over incisal edges and cusps of teeth is critical, just how thick should a mouthguard be and especially in these two areas? Transmitted forces through different thicknesses of the most commonly used mouthguard material, ethylene vinyl acetate (EVA) (Shore A Hardness of 80) were compared when impacted with identical forces which were capable of damaging the oro-facial complex. The constant impact force used in the tests was produced by a pendulum and had an energy of 4.4 joules and a velocity of 3 meters per second. Improvements in energy absorption and reductions in transmitted forces were observed with increasing thickness. However, these improvements lessened when the mouthguard material thickness was greater than 4 mm. The results show that the optimal thickness for EVA mouthguard material with a Shore A Hardness of 80 is around 4 mm. Increased thickness, while improving performance marginally, results in less wearer comfort and acceptance.

The global sports-media nexus: Reflections on the 'Super League Saga' in Australia

Despite the social and (increasingly) commercial significance of sport and sporting bodies worldwide, they remain under-represented in the mainstream management literature. One of the more recent and dramatic examples of the global sports-media nexus is the 'Super League saga' in Australia. This paper recounts the tale of the Super League saga, providing a holistic analysis of the events and competitive issues arising by drawing on literatures concerning the economic nature and value of sports leagues, the resource-based view of the firm and the nature of psychological contracts in changing environments. The analysis confirms the general monopolistic tendencies of professional sports leagues in an increasingly global industry driven by the sports-media nexus, in accord with a number of comparable cases internationally. The particular conditions of the Australian marketplace that exacerbate this tendency beyond, for example, that found in the USA, and differences in the outcomes of battles between rival leagues are also considered. The Super League saga portrays the importance of effective management of resources key to the production of the 'rugby league product' including, among others, the often over-looked importance of careful management of local resources for the success of global strategies, and, where human resources are key, the importance of psychological contracting. The holistic analysis of the Super League saga in Australia affords lessons that extend well beyond the realm of sports.

Whither our Art? Clinical Wisdom & Evidence-based Medicine

The relationship between evidence-based medicine (EBM) and clinical judgement is the subject of conceptual and practical dispute. For example, EBM and clinical guidelines are seen to increasingly dominate medical decision-making at the expense of other, human elements, and to threaten the art of medicine. Clinical wisdom always remains open to question. We want to know why particular beliefs are held, and the epistemological status of claims based in wisdom or experience. The paper critically appraises a number of claims and distinctions, and attempts to clarify the connections between EBM, clinical experience and judgement, and the objective and evaluative categories of medicine. I conclude that to demystify clinical wisdom is not to devalue it. EBM ought not be conceived as needing to be limited or balanced by clinical wisdom, since if its language is translatable into terms comprehensible and applicable to individuals, it helps constitute clinical wisdom. Failure to appreciate this constitutive relation will help perpetuate medical paternalism and delay the adoption of properly evidence-based practice, which would be both unethical and unwise.

Severity of sports-related concussion and neuropsychological test performance

Concussion severity grades according to the Cantu, Colorado Medical Society, and American Academy of Neurology systems were not clearly related to the presence or duration of impaired neuropsychological test performance in 21 professional rugby league athletes. The use of concussion severity guidelines and neuropsychological testing to assist return to play decisions requires further investigation.