Heading a modern-day football is not significantly safer than an old-style leather ball, a study by ballistics experts has found.
The study measured the impact of old and new footballs
Experiments conducted by scientists at the University of Glasgow showed the impact created on players' heads had a similar force.
High-speed cameras showed both balls collapsed to about half their diameter.
Ballistics engineer Alan Birkbeck said it was like being struck by 10 bags of coal for 3/100ths of a second.
Mr Birkbeck said: "We captured pictures of an old-style and a modern ball hitting a wall at high speed, the speed that a professional footballer kicks the ball.
"What we found was that the force was enough to collapse both down to about half their diameter.
"We also weighed the leather ball when it was bone-dry and weighed the modern ball and there was only a gram or two of a difference.
"We then soaked the leather ball in water and this only added another gram of weight making the difference only a scale of two or three grams."
In 1998, former Celtic player Billy McPhail lost his legal case for disablement benefit over a claim that he developed the first stages of senile dementia as a result of heading the old fashioned, heavy, leather footballs.
However, in 2002 an inquest into the death of former West Brom striker Jeff Astle ruled that he died from a degenerative brain disease caused by heading heavy leather footballs.
Mr Birkbeck, a senior engineer at Glasgow's Mechanical and Engineering Department, said: "The modern ball is not really safer, a professional footballer strikes it at 80 or 90mph - with your head in the way that's the equivalent of being struck by 10 bags of coal in 3/100ths of a second.
"With an impact like that you would really want it over a longer time, rather than a short, sharp blow.
"Personally, I'd rather be punched by a boxer."