Concussion is now a powder-keg issue in world sport, as concerns deepen about the potential links to brain disease.

The long-term effects of careers spent making and taking heavy tackles are being revealed in ever-increasing detail, but the risks are not exclusive to so-called full contact sports.

Some governing bodies have sprung into action, implementing new rules and safety measures. But others turn a blind eye.

Presenter: Paul Connolly

(Photo: Denver Broncos wide receiver Wes Welker (83) lays on the field after getting a concussion in the second quarter. Credit: Getty Images)