Wednesday 1 July 2015 11:07, UK
Graham Rowntree has warned England's squad they must be ready to go through the pain barrier as they prepare for the World Cup in September.
The tournament hosts started week two of their summer training camp at Pennyhill Park amid sweltering heat with the temperature set to climb all week
The players are being subjected to a gruelling conditioning programme and forwards coach Rowntree insists no allowances will be made for the weather.
"We want endeavour from the lads, we want them to be pushing themselves to the limit and go to a place they've never been before," he said.
We've got some horrible sessions planned for them, which is as it should be. They need that training to reach the fitness levels we aspire to
"We've got some horrible sessions planned for them, which is as it should be. They need that training to reach the fitness levels we aspire to.
"They're doing that so far because that's what you need to do to win a World Cup. They need to be as fit as they can be. They're training harder than I've ever seen."
England spend three weeks at their base in Bagshot before heading to Denver for a fortnight at altitude on July 10, reducing their squad by five players to 45 in the process.
One player certain to be heading to Colorado is Bath's rugby league convert Sam Burgess, who has impressed during training so far.
Rowntree, however, insists a decision has yet to be made on whether England view Burgess as a blindside flanker or centre, the two positions he has been filling for his club.
"Sam is a bit too good looking to be a forward! At this point we're just looking at him and we've not made our mind up just yet," Rowntree said.
"We're doing generic rugby skills work at the moment, so we'll make that decision in a few weeks' time. I've been impressed with the way he plays the game, how quickly he's learning and he has great physicality.
"He's good around the group - there's an aura about him. There's a reason he's achieved everything he has in league."
England face Australia, Wales, Fiji and Uruguay in their World Cup pool with the Fijians first up on Friday, September 18 at Twickenham.
