"I caught a bit of heatstroke on the first day, which wasn't a good start," Maxwell told reporters in Dhaka.
"I think just doing some running outside, then going inside to do some fitness tests, and then going back outside didn't help too much.
"The body shut down a little bit but I was fine after the ice bath and plenty of fluids."
Australia, who arrived last Friday, limited themselves to light training Wednesday after their two-day warm-up match on the outskirts of Dhaka was cancelled due to flooding.
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"Yesterday was obviously pretty tough with the overnight and morning rain, all the moisture coming out of the ground and making sweaty work for us," he said.
The tourists trained in Darwin, in Australia's tropical north, before their Bangladesh tour to prepare for the hot and humid monsoon weather.
"The wickets here are similar to what we faced in Darwin, where it was perfect," Maxwell said.
"I think the guys are more than well equipped to handle whatever comes their way in the first Test."
Bangladesh have not played a Test against Australia since Ricky Ponting's team visited the country in 2006, six years after the hosts were granted Test status.
Cricket Australia agreed to reschedule the series this year only after Bangladesh promised intensive security.
The first Test starts on Sunday, with the second in Chittagong from September 4-8.
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