A blockbuster match at the Australian Open is going the distance. A palpable stillness blankets Rod Laver Arena as beads of sweat gather on the athletes’ skin, cascading to the floor ahead of yet another arduous point. Under the scorching sun, beneath a stifling heat, a universal question lingers — how hot is too hot to continue?
This year, heat hasn’t been a major talking point: Novak Djokovic’s verbal spat with a spectator is about as hot as the tournament has been so far, with temperate conditions meaning that play has been largely uninterrupted.
But a Grand Slam tennis tournament is just one example of the many major events held all over the world during the hottest months of the year, where the urgency to manage risk to help improve conditions for players, operational success and spectator welfare are becoming increasingly important.
For spectators and organisers alike, a common strategy to try and help answer this question is to take out a phone — if it hasn’t already overheated — and check the temperature as provided by the nearest weather station. While tempting, this method doesn’t provide the complete picture.
For starters, air temperature (measured in the shade) is only one of four factors to consider when trying to understand how weather impacts people. Heat added by the sun (radiant temperature), the movement of air around the individual (air velocity), and the amount of water vapour in the air (humidity) all also contribute to how someone responds to the heat.
Then, at an individual level, outside of risk factors that could compromise someone’s ability to regulate their body temperature during heat stress (e.g. medications, illness), the intensity of the activity being performed and the thermal properties of the clothes people wear will also change how hot they ultimately become.
If Rafael Nadal wants to understand the risks of playing his match scheduled for 1 pm that afternoon, presenting him with a list of environmental stressors and biophysical intricacies might only add confusion.
Next is the nature of weather stations themselves. While vitally important, information drawn from stations sometimes situated kilometres away from the specific local geography of each event (e.g. stadium structures, playing surfaces) makes on-site measurements imperative to ensure a more precise understanding of the immediate environment. This level of accuracy, provided the right devices are used, allows for high-quality information to be collected and cited to help tailor decisions to the unique circumstances of the event.
When striving to make informed decisions, acquiring a comprehensive set of information becomes essential.
A full assessment of human heat balance involves considering all the factors listed above, but the next challenge lies in transforming this data into actionable insights.
If Rafael Nadal wants to understand the risks of playing his match scheduled for 1pm that afternoon, presenting him with a list of environmental stressors and biophysical intricacies might only add confusion.
To bridge this gap between data and decision-making, researchers employ climatic stress indices. These indices aim to distill the complex interplay of temperature, humidity and other factors into a single, comprehensible number. Notable examples of this include the Wet-Bulb Globe Temperature (WBGT), Heat Index (HI), and Predicted Heat Strain (PHS) models, each offering varying levels of complexity and ease of use.
This single number doesn’t entirely solve the issue. If there is no actionable step to take, the number doesn’t provide any additional insight beyond each composite part used to construct it. This number must be paired with clear, evidence-based strategies that can be employed to help mitigate risk and optimise performance.
Some examples of these strategies include personalised hydration plans and frequent breaks, providing athletes the opportunity to cool down with interventions that have proven efficacy like electric fans or ice wrapped in wet towels.
This problem is being tackled by researchers at The University of Sydney who have developed, and are now commercialising, EMU systems to help manage the safety and performance of athletes, fans and officials.
By integrating specialist devices with an intuitive assessment of heat stress and clear, graded evidence-based strategies specific to the sport, organisers and athletes know what the risk is and what they can do about it.
In pursuit of success on the courts of the Australian Open, the marriage of cutting-edge research and practical decision-making is essential. As the stakes rise and temperatures soar, the ability to navigate the fine line between athletic achievement and human well-being becomes a defining characteristic of successful sports management.
When watching this summer, the blockbuster matches may be reaching their climax. But behind the scenes, the careful orchestration of climatic data, tournament logistics and athlete engagement ensures that the heat of the moment remains a spectacle rather than a threat.
Grant Lynch is a research associate for the Heat and Health Research Incubator in the Faculty of Medicine and Health at the University of Sydney.
Ollie Jay is a professor in the Faculty of Medicine and Health, and director of the Heat and Health Research Incubator at the University of Sydney.
Prof Jay has received funding from Tennis Australia to develop and implement a heat management system for the Australian Open since 2019.