Usain Bolt shares his success secret

The 29-year-old Jamaican sprint king surged home to anchor his team to victory in the 4x100m relay and secure his ninth gold medal

Usain Bolt said dedication to his sport was the key to his incredible Olympic career on Friday after capturing his unique 'triple-triple'.

The 29-year-old Jamaican sprint king surged home to anchor his team to victory in the 4x100m relay and secure his ninth gold medal.

Asked to explain his success, Bolt replied: "Dedication. I wanted it the most. I was never satisfied. I'm going to stay up late and have fun. I never knew this would happen when I started out."

With chants of "Usain Bolt, Usain Bolt" raining down from the Olympic Stadium, the sprint superstar knelt down and kissed the finish line.

Bolt's teammate Yohan Blake said the other Jamaican members of the relay squad had been determined to deliver a gold.

"We wanted to win to make Usain immortal and he is immortal," Blake said. "I've told him he should come back for 2020!"

Bolt meanwhile joked that he had given his team-mates an ominous warning not to let him down: "I told the guys I'd beat them up."