Seems like a lot of the US runners who train in Flagstaff do their faster/harder sessions at lower altitude in Sedona and Camp Verde. Supposedly the science indicates this is optimal. Is this something that the African runners in Kenya/Ethiopia/Uganda do? Seems like it would be pretty difficult to get to lower altitude from many of the areas where they live. If not, this seems like it might invalidate some of the thinking around "live high, train low".