Brain injury is an issue that continues to plague some of elite American football players in the United States and it is something the NFL and its players are facing.

Dr Bennet Omalu discovered Chronic Traumatic Encephalopathy (CTE) and has written a new book, Truth Doesn't Have A Side, about the disease and how some in the NFL wanted to silence his discovery.

He spoke to Al Jazeera from the US city of Sacramento.

US & Canada, United States