Cycling great Lance Armstrong returned to sporting competition on Sunday, finishing second in the Panama 70.3 Half Ironman.

The 40-year-old American retired from professional cycling last year following a career in which he overcame testicular, brain and lung cancer to win the Tour de France seven times in succession.

Armstrong competed in amateur and professional triathlons as a teenager, before focusing solely on cycling.

Making a return to the triathlon, he finished second following a 1.9km swim, 90km cycle and 21km run in Panama City.

"I need a challenge in my life," he said. "I need some stuff to do. I like to train. I like to suffer a bit and today was a little over the top, but it's great to be back."

Armstrong, who clocked a time of three hours 50 minutes 55 seconds, led going into the final leg of the event, before being overtaken late by New Zealander Bevan Docherty (3:50.13), a gold medal winner in triathlon at the 2004 Athens Olympics.

Armstrong is set to compete in Ironman France this June, in an attempt to qualify for October's world championships in Hawaii.

The Ironman event involves a 3.86km swim, 180.25km bike race and 42.2km run, double the distance of a regular triathlon.

Earlier this month US federal prosecutors closed an investigation into allegations of drug use levelled at Armstrong by former team-mate Floyd Landis, with no charges laid.