rekrunner wrote:
Let's forget oxygen uptake. Let's forget any claims of performance beyond human limits. Let's forget about metabolic booster. These are all red-herrings.
Let's also forget multi-faceted performance improvements, because we are only interested here about altitude versus no altitude.
Let's only talk about altitude training and only talk about the consequences of that.
We saw in a 1997 study that short term improvement from atltitude training was fact.
In the same time frame with similarly composed groups, hi-lo training was better than hi-hi training, which was better than sea-level training.
We saw remarkably similar conclusions in anecdotes in a 2003 letsrun post from Jack Daniels.
Discus.
It would seem when we take away all the red-herrings, and try to limit an altitude discussion to altitude, there is nothing to add.
To re-iterate the answer to the OP's question, Stray-Gundersen and Levine found average improvements for non-elite athletes of 1.5-3.0% for non-elites, spanning the range of 0-6% for individual improvements.
Admittedly, the discussion of "how" or "why" goes one-step beyond the question of "how much", but it is worth exploring the various proposed mechanisms, or new mechanisms, to gain a better understanding of what athletes and coaches can try to do to improve performance.
Besides the classic explanation of increased red blood cells leading to an increased VO2max leading to improved performance, the only alternative contribution that was altitude related was "Hi lo has training has the advantage of changes in air humidity and temperature which are important considerations for athletes."
This raises the question: wouldn't hi-hi training also have the same advantage of changes in air humidity and temperature?
Unfortunately this proposal was not developed further.
Recall what we observed, not as speculation or theory, but as real time-trial improvements under carefully constructed and controlled environment with altitude as the main variable:
- hi-lo training improved in all subjects over the course of the study during all phases: control, intervention, post-intervention.
- hi-hi training subjects did not improve performance at altitude, despite increases in VO2max, but they did improve on return to sea-level.
- sea-level subjects did improve in the first "sea-level control" phase of the study, but regressed to their initial performance level post-intervention.
So far the question, and the studies, focuses on non-elite athletes (or as fast as the 30-minute 10K athlete). What about elite athletes? If non-elite subjects improved on average 1.5-3.0%, we should expect:
- elite athletes have smaller margins for improvements.
- athletes already at altitude have already gained altitude related improvements.