Sports headgear: What is concussion and can you stop it?

There is "potential" to reduce concussion in rugby by introducing new protective headgear, an expert has said.

Cardiff University and its partners got £165,000 via a competition co-sponsored by America's National Football League to develop an anti-concussion material.

World Rugby has previously said evidence does not suggest headgear prevents concussion.

Dr Peter Theobald, of Cardiff University, explains what concussion is and how you can reduce it.