" Anaerobic fitness, that is, the body's capability at responding when there isn't enough oxygen for the muscle, is necessary to charge up hills and past competitors on the finish line. A common saying for runners is that the sport is 90% mental . Recreational running became popular due to high-profile runners such as Steve Prefontaine. Race courses are usually held on the streets of major cities and towns but they could be on any sealed road. Most road races are either 5 km (3. 1 miles), 10 km (6. 2 miles), half-marathon (21. America Race Walking Athletes 097 km, 13. 1 miles), or marathon (42. "