He was responding to criticism from a coaching predecessor about the team's recreational activities.
After being criticised by former England coach Dick Best, Johnson said yesterday his side was full of "big boys".
"What they do at training is far more dangerous than what they were doing [as recreation]," he said at the team's press conference.
The 2003 World Cup-winning captain said as well as being in New Zealand for rugby, the players were also here to enjoy themselves and find a balance.
But they didn't go skiing because that would be "too risky".
Best had said he was surprised seven players had taken part in a series of "extreme sports" including the Shotover Jet and a bungy jump in Queenstown.
Tom Palmer, James Haskell, Nick Easter, Chris Ashton, Simon Shaw, Dylan Hartley and Ben Foden took part in jet-boating, a helicopter ride and white-water rafting on Monday.
Best, a former British and Irish Lions coach, also questioned whether players had breached their contracts with the England Rugby Football Union.
He said the activities were not something he would have allowed players under him to do.
Johnson said what the squad did while in Queenstown was completely normal for professional rugby players to be doing during a World Cup.
England halfback Ben Youngs did not take part in the activity day, but said that was merely because he was "petrified of heights".
"Obviously we train very, very hard. It's a lot of pressure and . . . it is nice to be able to just relax and get away from the World Cup, even if it's just for half an hour, of doing that. It's good fun and it's great that they let us do it."
