Monday, July 1, 2013

Early Week 4 update: Hypoxic training vs. Aerobic conditioning


Brian Oestrike from mentioned something I had not really considered before our conversation - the tradeoff between hypoxic training and aerobic conditioning.  Most mountaineers do not need to worry about this tradeoff because it only exists if the person trains at high altitudes and only a few lucky people get to live at or above 9,000 feet.  When you sleep in a hypoxic tent and workout in a hypoxic environment, you need to consider how much those environments affect your aerobic conditioning.  Consider the evidence to date.

Prior research shows that sleeping in a hypoxic tent improves aerobic conditioning.  The research on hypoxic training appears mixed at best. Some studies suggest there are no significant benefits to hypoxic training on sea-level performance while other studies show slight improvement without a clear mechanism.  One thing is certain from all these studies, short-term hypoxic training provides little to no benefit; hypoxic living (e.g., sleeping in a tent) and training at sea-level does provide a benefit.  The literature refers to this effect as the "Live High-Train Low" or LHTL.  A great summary of these effects come from a review article published in 2001:

"The accumulated results of 5 different research groups that have used controlled study designs indicate that continuous living and training at moderate altitude does not improve sea level performance of high level athletes. However, recent studies from 3 independent laboratories have consistently shown small improvements after living in hypoxia and training near sea level."  Hahn & Gore, 2001

One of the above authors provided the counterpoint perspective in this well-articulated debate.

If hypoxic training offers little conditioning or performance benefit at sea-level, does it offer any benefits at altitude?  Scores of studies suggest a strong benefit - even untrained subjects benefit from hypoxic training when performing at altitude.  So if there are clear benefits at high altitude, why on earth why there be a tradeoff?  Hypoxic training does provide benefit at altitude but it also decreases the workload possible while training.   If you exercise in a hypoxic environment, you cannot workout very hard.  Just try running up a mountain - even at the top of a chairlift.  You will find that the steps get increasingly more difficult for even the fittest person.  We cannot sustain the same workload so we experience a detraining effect.  

Brian's comment lead me to search the literature and left me wondering which side do I prefer - hypoxic readiness or aerobic conditioning.  Since the literature clearly supports the former, there is little doubt that the latter is essential on Everest.  He said he tends to lean toward hypoxic readiness.  I remain uncertain but plan to test out one training plan after another to see what suits me best.  Expect more updates on this matter shortly.

Controversy Surrounding Simulated Environments

While searching for relevant literature, I stumbled upon several articles that discussed the ethics of simulated environments such as the hypoxic machine I use.  One paper described the controversy well with respect to Australian football but the author's conclusions apply just as well to any other sport.  I intend to discuss this further in an upcoming post.

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