Ma-Kalambay bounded off his line but failed to make contact with the ball as Smith arrived on cue to plant a firm header into the net from 12 yards and hand Orient a shock lead.

BBC: Swansea 1-2 Leyton Orient

The data showed the average forces of a soccer-ball header were similar to those exerted on the head by punches from amateur boxers, according to Daniel Plant, a researcher in Imperial's department of mechanical engineering, who presented the data Friday at a helmet-safety science conference at the university.

WSJ: Soccer 'Header' Impact Likened to Hard Punch