In countless cartoons and choreographed TV wrestling, a thump to the head is inevitably followed by the victim performing a quick side-to-side recovery shake.

Now, US concussion and rehabilitation medicine researchers have noticed this involuntary action is common on the real-life sports field and suggest it could be a useful screening tool.

It has led them to call for its recognition as a clinical sign alongside others such as moving clumsily, loss of consciousness, slowness in responding to questions, partial amnesia and staring.

Led by pro wrestler-turned neuroscientist Dr Chris Nowinski (PhD), the study surveyed 347 young athletes from a variety of sports.