Four British former Special Forces soldiers, including a UK government minister, have set a record by climbing Mount Everest in under five days without acclimatising on the mountain. Their high-speed ascent was aided by xenon gas, which is believed to help the body adapt to low oxygen by boosting red blood cell production through increased erythropoietin levels, according to BBC.

The team reached the 8,849-metre (29,032-foot) summit early Wednesday, accompanied by five Sherpa guides and a cameraman. Typically, climbers spend six to eight weeks acclimatising on Everest before attempting the summit. Organisers credit xenon for enabling this rapid ascent. However, the use of xenon remains controversial, with many experts and members of the mountaineering community questioning its safety and effectiveness.

Despite this achievement, the fastest Everest climb overall still belongs to Lhakpa Gelu Sherpa, who summited in under 11 hours after acclimatising, BBC reported.