Gardner, 26, insists there has never been a problem with the players' work ethic.
He said: "There's been people talking and chatting about this, but it's a load of rubbish. The gaffer's come in and it's the same. Every football club has to work hard.
"We're working hard - we have to if we want to stay in the Premier League.
"We work hard every day. No matter what manager comes in, we're professional footballers.
"I don't know where this has come from, that Paolo Di Canio will work us harder, because at any club, there's only one place you'll be found out, and that's on the pitch."