[ElDiabloJoe]

Originally Posted by rrtjp

I don’t understand why a runner or a walker rather use the street than a sidewalk or path?

Because paths are short and sidewalks have the driveway up and downs and intersection curbs, not to mention uneven sidewalk cracks caused by roots - that constant uneven surface is murder on a runner's calves and shins and leads to injury. In addition, focusing on those dynamic surfaces takes away from the "in the zone" a runner's head strives to get into for training purposes. A serious runner is trying to focus on one's breathing patterns (breaths to steps ratios) to maximize oxygen exchange in the lungs and pace to increase performance

Remember, we are talking about MILES and MILES at a time. Only streets (and occasionally paths along an ocean) have the miles of non-stop, graded level terrain that allows a runner to truly train for distance racing.