Footballer Ruud Van Nistelrooy has been ruled out of Holland's World Cup squad due to doubts about his fitness following a knee injury.

The 33-year-old former Manchester United frontman recently moved on loan to German side Hamburg in a bid to prove his fitness after suffering a knee injury while playing for Real Madrid.

However, Dutch coach Bert Van Marwijk revealed that he had doubts that the striker had done enough to demonstrate his fitness for the tournament in South Africa.

He said: "I believe that Ruud is fit, but after his lengthy knee injury he does not have time to get back to his old level."

The news could spell the end of van Nistelrooy's international career with the Dutch team.

Those looking to boost their fitness quickly after a knee injury may find that using ultrasound at home helps this process by speeding up their recovery.

Knee injuries have been a feature of the player's career, with his original move to United in 2000 being put on hold for a year after he damaged ligaments and required surgery.