Last week, a group of four British mountaineers reached the summit of Mount Everest and completed their round trip from London in less than a week. This expedition duration is significantly shorter than the usual weeks required for acclimatization and ascent of the world’s highest mountain, followed by the return journey.

Speaking with the New York Times, their guide attributed this swift achievement to a unique advantage: before embarking on their journey, the climbers used xenon gas, which might have eased their adaptation to the low-oxygen conditions on Everest. However, experts specializing in the medical applications of xenon remain skeptical about its crucial role in this success.

“It’s possible there’s an effect, but it’s not yet confirmed,” states Andrew Subudhi, a professor at the University of Colorado Colorado Springs, who studies human performance in low-oxygen environments. “We’re still looking for solid scientific evidence or a proof-of-concept,” he adds.

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Understanding Xenon’s Effects

Xenon, a colorless, odorless noble gas, impacts the body in several ways. Since the 1950s, it has occasionally been used as an anesthetic, according to Robert Dickinson, a senior lecturer at Imperial College London. Dickinson studies xenon’s neuroprotective effects, which have been observed following brain injuries like strokes or traumatic impacts. These effects have been supported by numerous animal studies and a few small human trials.

The neuroprotective and anesthetic properties of xenon are due to its ability to bind to N-methyl-D-aspartate (NMDA) receptors in the brain. While these receptors typically stimulate neurons, xenon reduces their activity. This could be crucial after a brain injury when overstimulated NMDA receptors lead to further cell damage. By dampening this response, xenon could potentially help prevent further injury.

Beyond its medical uses, xenon has attracted attention in sports medicine due to its ability to boost the production of erythropoietin (EPO), a hormone that increases red blood cell production. These cells are essential for carrying oxygen, which is scarce at high altitudes like those on Everest.

Is Xenon Effective for High-Altitude Acclimation?

Typically, Everest climbers spend weeks acclimatizing in Kathmandu and at Everest Base Camp to avoid altitude sickness, which can cause symptoms such as fatigue, headaches, nausea, and confusion. In severe cases, it can lead to fluid in the lungs or brain swelling, both potentially fatal. The air at Everest Base Camp has about half the oxygen available at sea level, and the summit air only about 33 percent.

While xenon’s ability to boost red blood cell production could theoretically enhance athletic performance or prevent altitude sickness, its actual effectiveness in high-altitude conditions remains unproven. Davide Cattano, an anesthesiologist at the McGovern Medical School at the University of Texas Health Science Center at Houston, remains skeptical, despite studies showing that xenon increases levels of hypoxia-inducible factor 1-alpha, which boosts EPO production. “The induced levels of HIF don’t support the extraordinary capabilities attributed to it,” he comments.

A 2019 study in the Journal of Applied Physiology tested the effects of inhaling xenon on 12 runners. While these athletes showed higher EPO levels, there was no noticeable improvement in their physical performance or fitness. Moreover, even direct EPO injections have not reliably prevented altitude sickness or enhanced performance at high elevations, according to Subudhi’s ongoing research.

Factors Behind the Fast Ascent of Recent Everest Climbers

Experts speculate that xenon might have improved the climbers’ capacity to carry oxygen by boosting their EPO levels. Additionally, xenon’s anesthetic and analgesic properties could have alleviated their altitude-related discomfort, suggests Cattano. Breathing a dense gas like xenon might also have expanded lung capacity, albeit slightly.

However, the climbers also pre-acclimatized by sleeping in hypoxic tents, which simulate low-oxygen environments, increasing EPO and red blood cell counts. This preparation, combined with their rigorous training, likely played a significant role. Whether xenon provided any additional advantage remains uncertain, notes Dickinson.

Given its high cost, xenon use has been limited in both medical and athletic contexts. However, considering the extreme expenses and high stakes of climbing Everest, more individuals might opt to use the gas, Subudhi predicts. “At such high altitudes, where every small advantage counts, some might find it worthwhile,” he concludes.