Volume 11, Issue 1 , Pages 1-2, January 2008
Heat stress—A challenge for sports science in Australia
Article Outline
This issue of the Journal of Science and Medicine in Sport arises from the need for Sports Medicine Australia (SMA) to provide evidence-based guidelines for conducting sport in hot weather that are applicable throughout Australia.
In 2001 SMA released a national policy titled ‘Preventing Heat Illness in Sport’. The aims of the policy were to (1) alert sporting bodies and participants of the risk of heat illness from physical activity in hot weather conditions. (2) Provide a clear cancellation policy for sporting bodies conducting events in hot weather conditions. (3) Educate sporting bodies and participants on methods of minimizing the risk of heat illness and the avoidance of situations that may worsen heat illness. The policy recommended the wet bulb globe temperature (WBGT) as the best measure of heat ‘strain’ and indicated levels of risk of heat injury according to the WBGT. Specifically the policy stated that “At WBGT greater than 28 degrees Celsius there is extreme risk of heat injury to all participants”, and prescribed that “sporting events or activities requiring moderate to intense exercise should be postponed or cancelled when the WBGT exceeds 28 degrees Celsius”. The policy was based on the 1984 American College of Sports Medicine Position Stand—Prevention of Heat Injuries During Distance Running.1
The Queensland branch of SMA soon questioned this policy. They pointed out that if the direction regarding cancellation/postponement was to be followed Australia-wide no responsible sporting agency would risk scheduling any competitive sport during the summer months in Queensland. Yet a wide range of amateur and professional sport is enjoyed in Queensland on a daily basis in summer without undue restriction, and there is little evidence of catastrophic heat injuries during sporting participation.2
Queensland's concern highlights the difficulty of setting environmental limits for sports participation. Such limits must be based on good evidence that unacceptable numbers of heat casualties would occur if sport was carried on in conditions that exceed the limits; otherwise they are likely to restrict sport unnecessarily. Environmental limits might also vary between geographical regions because humans adapt to variations in climate through factors such as behaviour and acclimatisation.
Heat casualties do occur in Australian sport, but they affect only a small number of participants. They are not restricted to energetic sports such as running and football, but can also occur in cricket, golf and bowls,3 presumably because these sports can involve long periods of exposure to hot weather. Hot and humid conditions are usually considered to be the principal cause of heat casualties in sport, but exertional heat exhaustion also occurs in cool weather in community fun runs such as the Sydney City to surf. Over-motivation and running too hard with inadequate training appears to cause many of these cases.4 Most cases of sport-related heat illness are probably post-exercise hypotension or heat exhaustion.5 With initial aid they recover without complication and need for referral to the health system. Heat stroke seems to be rare.3
Answers to some fundamental questions are required to develop evidence-based management of heat stress in the wide range of sports enjoyed throughout Australia. These are what are the incidence, nature and severity of heat casualties, and in what sports do they occur? What are the human factors, including behaviour, and what are the environmental factors, that result in heat casualties? What are the impacts of environmental heat on comfort and performance? What are the most appropriate methods for assessing and predicting the impact of heat stress on sports participants? This issue of the journal addresses some of these questions. If it does not provide all the answers, it does aim to focus attention on relevant targets and challenges for research to develop objective strategies for managing heat stress in sport.
In 2005 Sports Medicine Australia released revised guidelines for playing and exercising safely in hot weather.6 The guidelines note that heat stress varies with exercise intensity, they warn of the dangers of over-motivation, and they point out the need to watch for potential heat casualties in vigorous activity, even in cool weather. They recommend modifying activities according to environmental conditions including the options of postponing or cancelling events. They also stress the importance of prompt assessment and first aid to minimize the impact of heat illness.
I am most grateful to all the authors who have contributed to this issue of the journal, but especially to Grahame Budd; Tim Driscoll and Ray Cripps; Caroline Finch and Soufiane Boufous; Mark Hargreaves; and Timothy Noakes for their generous responses to my invitation to contribute papers.
References
- . Prevention of thermal injuries in distance running. Med Sci Sports Exerc. 1984;16(5):ix–xiv
- Young M, Letter to B. Mitchell, Sports Medicine Australia, on behalf of Sports Medicine Australia Queensland. Dated October 1, 2002.
- . Heat-related injuries resulting in hospitalisation in Australian sport. J Sci Med Sport. 2008;11(1):40–47
- . Exertion-induced heat exhaustion and other medical aspects of the City to Surf fun runs, 1978–1984. Med J Aust. 1984;41:799–805
- . A modern classification of the exercise-related heat illnesses. J Sci Med Sport. 2008;11(1):33–39
- Sports Medicine Australia. Beat the Heat Fact Sheet. Playing and exercising safely in hot weather. http://www.sma.org.au/information/policies.asp [last accessed October 3, 2007].
PII: S1440-2440(07)00267-8
doi:10.1016/j.jsams.2007.10.014
© 2007 Sports Medicine Australia. Published by Elsevier Inc. All rights reserved.
Volume 11, Issue 1 , Pages 1-2, January 2008
