Two Texas sisters, ages 12 and 10, run in some of the most grueling races in the nation, but doctors say they are not in danger despite how young they are... The national championship trail run was held on a course both grueling and beautiful, more than 13 miles through the mountains near the Great Salt Lake. Most of it was an unrelenting up-and-down, the path often hugging ridges along a steep plunge, curling through a forest of scrub oak, white pine and red maple. The elevation hit a lung-busting 7,300 feet.