You can take this for what it's worth. The mecca of Kenyan running is the little town of Iten, located on the escarpment next to the Great Rift Valley (alt 2500 m). With the exception of the dirt track used for speedwork T & Th there isn't a flat piece of real estate around. There is only one paved road through town. Unless it rains, ALL training is done on dirt roads in the farm fields with hills, hills, and more hills. And I'm not talking about rolling rises here. These guys train at 6am, 10am, & 4 pm seven days a week. No smooth surfaces no flat terrain. There is one thing I've noticed they do not execute that many Americans do. They do not increase their pace downhill. They pretty much keep a quick even pace uphill & downhill. Not a lot of injured Kenyans around here.