Alex Rance, a key defender with AFL club Richmond, sheds as much as 4 kilograms after playing a match in warm conditions, roughly twice his weight loss of a more regular game.
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Fatigue is noticeably worse during hot games, with some teammates taking weeks to fully recover, the tall Tiger says.
Mr Rance also worries that a delayed start to 2015 season because of the Cricket World Cup will add to health risks facing players as this year's matches extend into October.
"It's certainly raising the probability that it will be a lot hotter in the finals, and it will increase the risk of injury, I've got no doubt at all," Mr Rance said.
As the training and playing seasons for winter sports such as AFL and NRL stretch ever further into the warmer months, traditionally summer pastimes such as cricket and tennis – and their fans - are also facing greater risks from playing in extreme heat.
Australia's average temperatures have risen almost one degree in the past century and climate change threatens to lift that increase to as much as 5 degrees by 2090 with many more extreme days, the CSIRO and the Bureau of Meteorolgoy said in a report this week.
If the worst projections play out, by 2090 Melbourne's current climate will look like Dubbo's in central NSW today, while Sydney's will resemble Bundaberg in Queensland. A lower trajectory for greenhouse gas emissions will see Melbourne resembling Cowra in southern NSW, with Sydney shifting to a Brisbane-like climate.
For Perth, the number of days annually above 35 degrees would more than double to 63 – effectively two months – with a similar jump predicted for Adelaide to 47.
'Back seat' for sport
A new report by The Climate Institute on how Australian sport is dealing with current and projected temperature increases found a patchy response.
"Most sports are struggling to cope, especially at the local level," it said. "Heat policies are often ambiguous and vary at state, national and international level."
"This should, in many ways, be like occupational health and safety," John Connor, the institute's chief executive, said, noting some unions stop outdoor work on 35-degree days.
Andrew Demetriou, former AFL chief executive and a Climate Institute board member, said it was inevitable that sports managers would have to prepare with climate change.
"Elite sports will have cope with rising temperatures, that's just a fact," Mr Demetriou said. "In the whole climate debate, sport has so far taken a back seat."
This summer's sport largely dodged a repetition of last January's record-breaking heatwave across southern Australia that led to players and several ball-kids collapsing at the Australian Open.
The Asian Football Cup, which culminates with Socceroos taking on South Korea for the title in Sydney on Saturday night, had prepared for cooling and hydration breaks at the 30th and 75th minutes if needed.
The trigger - which wasn't pulled - was a reading on the wet-bulb globe temperature of 32 degrees or higher, taking into account heat in the sun, humidity and other factors.
For the Australian Open, a WBGT reading of 32.5 degrees would have been enough to halt play at the Australian Open, subject to the umpire's discretion.
Other sports have a range of limits, such a standard 38 degrees for Cycling Victoria and 36 degrees for Victorian country AFL games.
'Hot box'
Professional teams such as Townsville-based Cowboys in the NRL already have to deal with high humidity and temperatures. On warm days, players begin training at 6am and stop by 10am, Michael Luck, a manager of the Cowboys, said.
Handling the heat can be a struggle for visiting teams. "We certainly try to use it our advantage early in the year," Mr Luck said.
But for NRL rivals, the Gold Coast Titans, training in the Queensland heat and in a specially built "hot box" is a key part of the preparations for games, said Dan Ferris, head coach for strength and conditioning.
"We run our skills and fittness sessions on the Gold Coast between 12-3pm, generally the hottest part of the day, to ensure our players are well accustomed to training in the heat," Mr Ferris said.
The "hot box" has only a single entry point and "gets extremely hot during training sessions and takes our training to a new level in terms of players mental and physical fatigue", he said.
"Our players hated the 'hot box' at the start but once they became accustomed to training in it, the outside temperature didn't seem so bad - that's called adapting to heat training," Mr Ferris said. "We need to be able to increase our effort at the back end of games while teams are struggling to deal with the heat."
Humans typically start to suffer discomfort if core temperatures rise above 38 degrees, with life-threatening risk mounting if 40 degrees or higher conditions persist.
For the Titans, players are weighed pre- and post-training session, with any bodymass loss replaced with 150 per cent of fluids, Mr Ferris said. Other recovery steps include an ice-bath at 12-15 degrees, and close monitoring of the players' diets and sleep.
Richmond also has a "hot box", with 25 of AFL footballers shoulder-to-shoulder in regular sessions, sweating away on spin-bikes - "which sucks for us", Mr Rance said.
Ice baths, though, are no longer part of the mix, with the temperature of the water viewed by the Tigers' medicos as less important than the pressure placed by water on muscles to aid their recovery, he said.
But while elite athletes get access to an ever-widening range of support – from ice vests, hot rooms, physios and cramping pills – the same is not true for many non-professionals playing in extreme heat, Mr Rance said: "It's kind of risky for those guys."
