Exhausted but elated, Fiennes finishes his seven-marathon endurance challenge

From the sands of the Egyptian desert to the peaks of Patagonia, the explorers have endured extreme heat and cold in just one week.

Last night,, Sir Ranulph Fiennes and Dr Mike Stroud completed the final leg of their trans-global challenge to run seven marathons on seven continents in seven days. Exhaustion was replaced with elation as they crossed the finishing line in New York last night having set a world record.

"I feel fine. I do not feel tired," said Sir Ranulph, 59, moments after completing his arduous challenge. "The most difficult part was at the end of Singapore. I thought I was a goner. I thought I might not be able to go on."

Before setting off on the final leg of his feat, Sir Ranulph had described how he and his partner were determined to complete the seventh course, despite severe exhaustion and a string of injuries. "I've rogered myself completely in the hip but that won't matter in terms of finishing the challenge," said Sir Ranulph, who suffered a heart attack less than five months ago and has been followed by a medical team throughout his trip. "Unless something goes wrong we're confident it can be done." Dr Stroud, 49, added: "I'm just looking forward to finishing."

During the six previous days, the explorers had overcome technical glitches, physical injuries and inhospitable weather to complete runs in Chile, the Falkland Islands, Australia, Singapore, London and Egypt.

Upon completion of their feat when they arrive back in London, the pair will have clocked up 183 running miels and 45,000 miles of air travel.

Yesterday, they swapped the searing heat of Cairo for the autumnal chill of New York as they embarked on the city's official marathon. In contrast to their previous marathons, which involved running in the most remote of locations, the pair were joined yesterday by an estimated 30,000 competitors.

Sir Ranulph managed to reach the end of the 26.-mile course in Manhattan's Central Park in five hours 25 minutes.

Fellow runners included the rap star Sean "P Diddy" Combs, who hoped to raise $1m for children in New York by taking part in his first marathon. Before the run, Combs said: "It's going to be painful. But if we get through it, it's telling kids and everybody else to finish what you start, and you can do anything you put your mind to."

Despite only two months training for the event, Combs crossed the finishing lines in four hours 14 minutes.

Sir Ranulph had admitted he almost fainted during the Cairo marathon, which he completed in four hours and 21 minutes, due to a hip injury. The pair raised funds for the British Heart Foundation.