Frontline

PBS | 10:00 pm

With the official start of the National Football League’s new season at hand, this series repeats Part 1 of "League of Denial: The NFL’s Concussion Crisis," a 2013 episode that was a subject of controversy then over ESPN’s withdrawal from being named as a production entity on it. The program examines allegations that on-field collisions have caused players to suffer such maladies as early dementia, Alzheimer’s disease and Lou Gehrig’s disease.