He told BBC Radio Leicester: "I do struggle with my back from time to time but the last four years at Wigan I've played nearly every game.
"It's just a case of management - but I know my body now."
He added: "I know what I can and can't do.
"I've got a routine and it's worked pretty well over the last four years and hopefully that can carry on while I'm here."
Foxes manager Sven-Goran Eriksson, who called Kirkland into the England squad when he was was manager of the national side, was thrilled with the signing.
"He trained with England many, many times," Eriksson said. "But he never played because he had a back problem
"He was supposed to be England's number one - everyone thought that so he should be very good for us.
"And when an opportunity like that pops up you should take it."
The Swede was also delighted to bring in West Brom striker Roman Bednar.
"I saw him
play against us in the Carling Cup when we lost 4-1," Eriksson said.
"I've seen him before, I've had a lot of recommendations and, from what I have seen in training, he is a very good player.
"He has Premier League experience and international experience so he should be very good and I am sure he will be very good. He will give us more quality."
Source: BBC Sport
Source: BBC Sport