BARCELONA, Spain (AP) — Hikers navigating rugged terrain may have noticed more people speeding along the same trail while leaping over rocks and roots like two-legged mountain goats. Trail running has exploded in popularity in recent years. The sport encompasses everything from off-road jogs on unpaved coastal paths to alpine ultra-marathons. Extreme versions are known as mountain running , which involves moving and sometimes scrambling uphill on varied surfaces, and sky running, which is done