When Brandi Lebsack and her 11-year-old son, Kaden, first dived into “American Ninja Warrior”-style training last year, they made the 120-mile round trip from their home in Castle Rock to a gym in Longmont twice a week so he could run an obstacle course inspired by the famously punishing TV series. “He wasn’t a team-sports kid,” said Lebsack, 42.