The obvious problem with climbing at altitude is that there is less oxygen - a lot less! Luckily a number of physiological changes occur to allow for acclimatisation at high altitude. However, whilst the body's adaptation to high altitude helps significantly it doesn't fully compensate for the lack of oxygen. Oxygen, and how our bodies use it, is extremely important.
In his seminal book Extreme Alpinism Mark Twight highlights the importance of VO2 max as a reference point for your training. VO2 max is the maximum capacity of an individual's body to transport and use oxygen during exercise. It is an important determinant of endurance which represents true measure of cardiovascular capacity for an individual at a given degree of fitness and more importantly - for a given degree of oxygen availability.
Given Everest has about one-third of the oxygen of normal elevations and Ama Dablam has around 46%, how does the lack of oxygen impact VO2 max?
According to sportsmed "There is a drop in VO2 max of 2% for every 300 m elevation above 1500 m even after allowing for full acclimatization". West et al (J. Appl. Physiol 1983) measured VO2 max of subjects on supplemental oxygen approaching the summit of Mt. Everest, their mean VO2 max was determined to be a mere 15.3 (ml.kg-1.min-1). At sea level an averagely fit individual would have a reading of 45 to 50ml. Clearly chronic exposure to high altitude reduces maximal O2 uptake (VO2 max).
So is there a minimal VO2 max one needs to climb at high altitude?
Ed Viesturs who climbed all fourteen 8000m peaks without supplemental oxygen is well known for his physiological advantage, as his VO2 max is close to 70. This reading translated directly to his body being able to work better at high altitudes. Where most people would go anaerobic at 50 percent of their VO2 max, Viesturs holds out until 88 percent (National Geographic).Viesturs physiology is perfectly suited to make the most efficient use of the oxygen he has in his lungs. Combined with training, focus and a strong will, that makes for a more lucid, thoughtful climber, even without the use of supplemental oxygen.
Anecdotal evidence suggests that one would need a minimal 55 to 60ml reading in order to negotiate successfully high altitude climbs. Clearly the higher your VO2 max the better your chances of success, or rather a high VO2 max minimizes the chance that you have to turn around due to your own physical capabilities.
Conclusions...
To quote Steve Whittington from his excellent blog Quest for Everest
"My experience at high altitude has taught me that in order to be successful, I need to focus on being healthy and taking care of my body while up there. It may seem obvious to do this, but my hardest climbs have been when I did not pay attention to my body properly. This is harder than you may think, as a long expedition grinds you down and you lose focus and discipline".
Steve's words echo my own experiences, as such, like Steve, I am going to focus on 3 goals:
- Increase my VO2 max - For me my current reading is roughly 54 (via proxy tests). And whilst there are many journal reports to suggest that our maximal VO2 max is genetically based my intention is to gain as higher VO2 max as possible... More on how later!
- Increase Endurance and aerobic threshold - The anaerobic threshold is the point at which oxygen demand exceeds the bodies ability to supply it. The higher the anaerobic threshold, the greater your capacity to generate a given amount of energy without producing debilitating levels of lactate in the blood
- Put on muscle so my body has fuel to cannibalise at altitude
In the coming posts I'll go into more details of how I intend to do this... Now it's time for some recovery sleep before my 21km x-country run I have planned for tomorrow morning!
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