Above 3000m training becomes complicated, and, overall, above those heights, few athletes have profited.
Take the case of Marius Bakken, who trained extensively for several months in La Paz, Bolivia, the highest world capital at over 3000m.
Marius had run 13.11 the previous year, and then after the Bolivia quest, he did not go better than a modest 13.30 that year.
It was an 'experiment' for the, then, 23 year old Oslo University medical student. He experimented with training for between 4-5 hours a day. It all backfired, and Bakken never returned to that impoverished South American nation. A few months later, he returned to Eldoret, Kenya, situated around 1600m, with forays to Iten - 2300m. Those heights were much more manageable for him and other Euro and caucasian athletes.
Ghost in Saud,