Fonseca, running in the 60km Everest Extreme Ultra Marathon,  is one of the 17 participants competing in the world’s one of the most difficult marathon events dominated by Sherpas.

“I want to test and challenge the limitation of my body. Sherpas seem they are from another planet. It is almost impossible to beat them,” said Fonseca the winner of the Antarctic Ice Marathon & 100k ultra race.

Fonseca is among the 10 foreigners desperate to beat seven locals who are well accustomed with the conditions and landscape. The 60km race was introduced last year. Meanwhile, the full marathon will be competed by 135 runners — 96 foreigners and 39 locals. Five foreigners have registered to compete in the half marathon.

The marathon will begin from the Everest Base Camp, which lies at the 5,364 metres in altitude, and will end at Namche Bazar (3,450 metres). Event organisers Himalayan Expedition on Tuesday said all preparations for the event has been completed. “The check points are set at every 5-7 kilometres for the main event. Water supply and medical facilities will be available at the check points as required,” said Shikhar Pandey, the event manager, adding a helicopter has been kept standby in case of an emergency.

The marathon is organised to commemorate the day Tenzing Norgay Sherpa and Sir Edmund Hillary scaled the world’s highest peak, Mt Everest, for the first time on May 29, 1953.