Experiments measured the forces and acceleration of a regulation, adult-size-5 ball propelled repeatedly at a magnesium dummy-like head at 18 meters per second, which is considered the average speed a ball is kicked by nonprofessional players.

WSJ: Soccer 'Header' Impact Likened to Hard Punch

This boom can be squelched by oppressive regulation, or it can embraced, with attendant job acceleration in dozens of states.

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