Many years ago, I was reading a book in which the Chamonix guides of the 1940s and 1950s were featured. It could have possibly been Annapurna by Maurice Herzog, but I just don't remember.
Several sentences in the book implied that an older climber — one who made repeated trips to altitude over a period of years — acclimatized quicker on subsequent trips than younger, relative newcomers to altitude. (I remember the term "older climber".) This was a personal observation, and was not expanded upon. But this was probably written in the 1950s, and the mechanisms of acclimatization have received much scrutiny since then.
Is there any evidence to refute or support this hypothesis?
I can think of several possible explanations for this observation:
It is true that repeated trips to high elevation change the physiology of the climber to make acclimatization easier, quicker, more complete.
Climbers who repeatedly go to altitude develop conscious and unconscious habits that aid acclimatization (e.g., religiously staying hydrated when possible, getting enough sleep, avoiding alcohol, knowing when to retreat to refresh themselves, when to stop and when to continue.)
Climbers who repeatedly go to altitude grow accustomed to the discomfort of acclimatization and ignore the discomforts.
None of the above. The statement flatters older climbers.
And other explanations are also possible, including the fact that even if the hypothesis is true for Alpine altitudes, no European mountain approaches the high Andes or Himalayan altitudes.
Background: Note by older, the author (whoever he was) probably meant climbers in their 30s or so, not really old climbers. At the time of the Annapurna expedition (1950), Louis Lachenal was 29, as was Lionel Terray and Gaston Rebuffat. Maurice Herzog was 31. On a modern note, Ed Viesturs climbed his 14th 8,000er, Annapurna, at 46, without supplemental oxygen.