How to Prepare for Running Long Distance. Long distance running, also called marathon running, involves running distances of 1.86 miles (3 km) or more, often in a competitive setting. 3K, 5K, 10K, half marathon, cross-country and marathon races are all examples of long distance running.ow to Prepare for Running Long Distance. Long distance running, also called marathon running, involves running distances of 1.86 miles (3 km) or more, often in a competitive setting. 3K, 5K, 10K, half marathon, cross-country and marathon races are all examples of long distance running.