Seven-time world champion Michael Schumacher admitted Sunday he had turned to dye to cover up his grey hair but the 41-year-old said he was now in perfect shape for Formula One.

The German star, who stunned the Formula One world in December by signing a three-year contract to drive for Mercedes GP, told mass circulation Bild: "I started to dye parts of my hair in, I think, 2005."

Schumacher also revealed he had had his eyes tested recently but insisted: "I do not need glasses."

And the former Ferrari legend said he had already burned off five kilogrammes (11 pounds) of weight that he had put on since calling time on his career in 2006.

Now at the ideal racing weight of 74 kilogrammes, Schumacher said his fitness regime revolved around swimming and playing football.

"I jog very little because I have had back and knee problems since the age of 14. But what is strange is that I can play three hours of football without any problems but I cannot jog for 45 minutes," he said.

"I now swim a lot. Half an hour of breaststroke per day makes an incredible difference."