Trail runners, was backpacking with my wife a few years back, just a weekend trip one day in and day out to this lake at the base of mountain. We started at 6am , little after lunch time a group of kids come running down the trail, full tilt. Later learned that it was the ski team corss training, they ran the full length of the trail we just trekked , then summited that mountain and made it back to were we started, and they do that 2 a week all summer. I mapped it out and those little psychopaths ran 20+ miles with 3000+ feet elevation change...