Manchester United and England striker Wayne Rooney should consider yoga and cryotherapy to prolong his career, according to Sunderland's Jermain Defoe.

Rooney, 30, has come under pressure in recent weeks following a perceived dip in form, with the United captain dropped to the bench for both club and country.

Defoe, 34, feels the criticism of Rooney is harsh, although he believes the former Everton player could benefit from adopting certain techniques to aid his ageing body, including cryotherapy which involves standing in a sub-zero chamber which can improve recovery times.

He said of his former England teammate in the Daily Mirror: "Is age an irrelevance? 100 percent. Ryan Giggs [who made his last Manchester United appearance at age 40] showed that. It was well documented the things he was doing, like yoga and pilates. Teddy Sheringham played until he was 40. I think Les Ferdinand was 38.

France women's international Amandine Henry undergoes cryotherapy in 2015. FRANCK FIFE/AFP/Getty Images

"I just think, if you do it right, if you look after yourself like I always have then you shouldn't have a problem.

"It's unbelievable [the criticism of Rooney]. People obviously forget what he's done and how much football he's played. Look at his record -- the highest goalscorer -- it's a little bit harsh in my opinion.

"Obviously there comes a point in a player's career where you can't get to the same level that you've been at before -- and you set such high standards it's hard to be the same.

"But people can't forget what he's done and the amount of goals he's scored, not only for England but for Man United as well.

"At one stage, he was the wonder-boy playing for his country and now people are getting frustrated and the phones are burning. But he's one of the best talents England have ever produced. It's harsh.

"I'd say get him in the cryo!

"He's 30 and some of the things he's achieved in the game are unbelievable. He's a goalscorer and when he gets the chances he can finish and he can create goals as well. But I'm not the manager of Man United or England."