Heat stress incident prevalence and tennis matchplay performance at the Australian Open.

OBJECTIVES To examine the association of wet bulb globe temperature (WBGT) with the occurrence of heat-related incidents and changes in behavioural and matchplay characteristics in men's Grand Slam tennis. DESIGN On-court calls for trainers, doctors, cooling devices and water, post-match medical consults and matchplay characteristic data were collected from 360 Australian Open matches (first 4 rounds 2014-2016). METHODS Data were referenced against estimated WBGT and categorised into standard zones. Generalised linear models assessed the association of WBGT zone on heat-related medical incidences and matchplay variables. RESULTS On-court calls for doctor (47% increase per zone, p=0.001), heat-related events (41%, p=0.019), cooling devices (53%, p<0.001), and post-match heat-related consults (87%, p=0.014) increased with each rise in estimated WBGT zone. In WBGT's >32°C and >28°C, significant increases in heat-related calls (p=0.019) and calls for cooling devices (p<0.001), respectively, were evident. The number of winners (-2.5±0.006% per zone, p<0.001) and net approaches (-7.1±0.008%, p<0.001) reduced as the estimated WBGT zone increased, while return points won increased (1.75±0.46, p<0.001). When matches were adjusted for player quality of the opponent (Elo rating), the number of aces (5±0.02%, p=0.003) increased with estimated WBGT zone, whilst net approaches decreased (7.6±0.013%, p<0.001). CONCLUSIONS Increased estimated WBGT increased total match doctor and trainer consults for heat related-incidents, post-match heat-related consults (>32°C) and cooling device callouts (>28°C). However, few matchplay characteristics were noticeably affected, with only reduced net approaches and increased aces evident in higher estimated WBGT environments.