"... runners: What types of injuries do they mostly had? ..."
Usual for hard surfaces, long distances - knee and calf issues mainly. For the knee we had ligaments going, tears in calf, no ankles though and exhaustion. Most carried old injuries of some sort. I'm not sure if lack of conditioning could explain it. My reckoning with some other experienced distance movers put it down to "knowing" the limits of how far you could push yourself at any given time.
