Smith's classy tribute to 'courageous' Root

Steve Smith has heaped praise on Joe Root after the England skipper's incredibly gutsy display on Day 5 at the SCG.

Root's nightmare maiden Ashes tour as captain ended in bouts of dehydration, diarrhoea and vomiting in the SCG dressing rooms.

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Taken to hospital to begin the day and twice retired hurt, Root was ill and asleep in the change rooms when Steve Smith lifted the series trophy.

The 27-year-old made it to the ground for the start of play with a hospital wristband still on, but did not come out to continue his day-four innings until after Moeen Ali was dismissed midway through the morning.

Symptoms returned when he went to lunch with his fifth half-century of the series though, ending his Test as Australia's quicks ran through England's tail to confirm the innings-and-123-run victory.

Speaking in the post-match press conference, Smith paid tribute to Root's bravery.

"He showed some real courage to come out and bat," Smith said.

"You could see that he was struggling a fair bit.

"He's a touch character so he must have been in a pretty tough way not to come back out after the break."

Root spent the most time of all players in the middle on Sunday during the hottest conditions for an Ashes Test in Australia, fielding for the first half of the day before being called to the crease just six overs into England's innings.

Temperatures at nearby weather bureau stations reached 43.4 and 43.7 degrees, above the record 43.1 taken during the 1908 Adelaide Ashes Test.

A heat stress tracker, taking into account environmental factors for a 'feels like' mark, at the ground also displayed a reading of 57.6 in the middle.

England blamed a gastro bug rather than Sunday's temperatures, but it still prompted debate on whether the International Cricket Council needed to introduce a policy to protect players in extreme conditions.

Former Australian Test batsman Dean Jones, famous for his hospitalising double century in extreme heat during the 1986 tied Test in India, called for games to be suspended in extreme heat.

"After speaking to a couple of doctors this morning ... in my opinion cricket should be called off after 41C ... it's a workplace issue now ... Just my opinion," he tweeted on Monday morning.

A common-sense approach is largely taken by match officials in elite Australian cricket matches during the heat.

Extra drinks breaks were added on Sunday, while medical officials kept a closer eye on players. Messages over the big screen also prompted fans to be sun-safe and hydrate.

A round of Sydney grade cricket - governed by the state body - was called off last summer in severe heat, however a Sheffield Shield match continued in the city in the same conditions.

But players in Shield and other elite matches have access to ice jackets, misting fans and scientific analysis that amateurs do not.

with AAP