“I think summiting Everest twice in one week without oxygen opens up a new realm of possibilities in alpinism...”
In 2017 ultra endurance athlete Kilian Jornet took the world of high altitude mountaineering by storm. Over the course of just 4 weeks he tagged 8000m on 4 occasions and in the process set a new speed record for climbing Mt Everest (8850m). A recent paper published in the International Journal of Sports Physiology and Performance describes the physical preparation and acclimatisation process that led to this incredible feat. In this blog we'll take a look at the paper and see what lessons there are for mountaineers who wish to venture to high altitude.
Kilian Jornet on the Bob Graham Round
Before starting, it's worth saying that Kilian Jornet is an extraordinary athlete. In the UK he's perhaps best known for running the Bob Graham Round in less than 13 hours, knocking more than an hour off Billy Bland's record that had stood for 36 years. However ultra running is just one of his many talents. As a climber, duathlete and ski mountaineer he has won countless events and set records that are likely to go unchallenged for many years. Underpinning his success is an extraordinary dedication to training. As the paper describes, in the year leading up to his successful Himalayan season Kilian completed 1140 hours of training with 40% of this taking place at an altitude of between 1800 and 3500m. It's worth pausing for a moment and doing the maths. That's an average of almost 3 hours of training every day for a year. If you take out the days spent resting, travelling and living a life that figure is considerably higher!
The hypoxic tent used by Kilian Jornet at sea level. The device on the right delivers a fixed percentage of oxygen and creates a simulated altitude of between 4000 and 5000m inside the tent*.
Whilst training goes some way towards 8000m success it is only part of the solution. The right acclimatisation programme is vital and Kilian's was unusual to say the least! Rather than head to the Himalayas and spend weeks gradually increasing his altitude exposure, Kilian did most of his acclimatisation at home. Living at sea level, Kilian slept for 8 weeks (260 hours) in a hypoxic tent that was designed to simulate altitudes of between 4000 and 5000m*. A further 90 hours were spent running hard on a treadmill or cycling a static bike whilst breathing the same hypoxic mixture. This wasn't a walkover - the intensity of these sessions were set between 65 and 70% of maximum!
Kilian Jornet preparing in the Alps.
Before flying to the Himalayas, Kilian spent a further 10 days preparing in the Alps. In total, his records show that he spent 100 hours sleeping and ski mountaineering at altitudes of up to 4200m.
So that's the preparation. What happened next?
On May 7th, just 10 days after arriving in Tibet, Kilian reached the summit of Cho Oyu (8201m). A climb that would normally have taken at least a month had been done in little more than a week. But that was only the start! He quickly moved to the north side of Mt Everest (8850m) and 8 days later (May 15th) climbed to 8400m in order to acclimatise further and assess the snow conditions on the mountain. After 5 days of rest, Kilian left Base Camp on May 20th and climbed the standard route in just 26.5 hours. This set a new speed record. If that wasn't enough, Kilian repeated the route from Advanced Base Camp (ABC) (6300m) 7 days later. Taking just 17 hours, this was believed to be the 3rd fastest ascent from ABC.
To underline Kilian's performance one statistic stands out. During his record breaking climb, his ascent rate between 6300 and 8400m was measured at 350m/hour. This figure is extraordinary - almost 50% quicker than anyone who had climbed Everest in the past!
Kilian Jornet with the climbing equipment he used on Everest. All 4 of his 8000m climbs were done without supplemental oxygen or fixed ropes.
What can the wider climbing community learn from Kilian's experience?
First, training does help. For far too long, there has been a belief that prior physical preparation has little impact upon high altitude performance. A combination of weak scientific evidence and eye catching anecdote have led some to argue that a well stocked base camp and a "never say die" attitude were all that was needed to reach an 8000m summit. Kilian's experience shows that this is not the case. Physical preparation is crucial to safe and successful high altitude mountaineering.
Kilian training on the treadmill with a hypoxic mask system*.
Second, acclimatisation can take many different forms. Whilst the traditional approach of climbing up and down mountains has worked for many of us, the availability of new equipment means that its now possible for much of the acclimatisation process to be completed at home. In future postings we'll take a look at what works and what doesn't!
For now, let's leave the final word to Kilian,
“In four weeks we have reached two 8,000m summits so it seems our acclimatisation has worked. We had been training in hypoxia for a few weeks before and we went to acclimatise in the Alps before coming here. It seems that this type of express acclimatisation works and the body tires less and as a result we’re stronger when it comes to the challenge.”
*How does a hypoxic tent or mask system work?
As you ascend to high altitude the number of oxygen molecules that surround you falls. This results in fewer collisions and a reduction in the pressure they exert on the objects around them. Oxygen needs a differential in pressure to move from the atmosphere and into the lungs. The higher the pressure, the more rapid the movement of molecules. If this pressure falls, the movement of oxygen falters and fails to get to the body's organs. This is what happens at altitude and causes a myriad of problems for the mountaineer!
The pressure exerted by oxygen molecules is known as the partial pressure of oxygen or PO2. At sea level the PO2 is 21 Kilopascals (KPa). This is calculated by multiplying the percentage of oxygen in air (21%) by the collective pressure of all of the different gas molecules present in the air at sea level (100 KPa). At 5000m, this pressure, commonly referred to as barometric pressure, drops to 50 KPa and results in a PO2 of 10.5 KPa.
A hypoxic tent or mask system can create the same PO2 at sea level as that found at 5000m. Rather than change the barometric pressure, the hypoxic system delivers a lower percentage of oxygen. By breathing 10.5% oxygen at sea level barometric pressure (100 KPa) it is possible to obtain a PO2 of 10.5 KPa. Hence, a "simulated" altitude of 5000m!