Wednesday 1 June 2016

Brain surgery: it isn't rocket science

I think that most English people of my age with an interest in (association) football will remember Jeff Astle, the prolific West Bromwich Albion centre-forward of the late-1960s and early-1970s; and his sad demise in 2002 (was it really that long ago?) following the early onset of Alzheimers. His illness and death were ascribed by the coroner to repeated minor trauma caused by heading footballs. Since then, it has become apparent that at least four of England’s 1966 World Cup final team have succumbed to Alzheimers (two died young from other causes). Anyone, like me, who played at any level in that era, will remember the shuddering impact resulting from any less than perfectly executed header of a waterlogged leather football; and I doubt that any of us would be surprised that professional footballers from those days, especially centre-halves and centre-forwards, seem more than averagely susceptible to Alzheimers.

I would also doubt that anyone, like me, who has played since then, when lighter and non-absorbent balls were introduced, remembers ever being hurt by a ball that they intended to head. Which is why I was surprised to see a Dr Michael Grey, motor neuroscience physiologist at the University of Birmingham quoted as saying “the heavy leather balls, in my opinion, is a massive red herring”. So I looked him up. He seems relatively youthful, and a native of British Columbia, so I doubt he’s ever got his head underneath a sodden leather football punted fifty feet high by a goalie.

We can forgive him his inexperience, but not his egregious grasp of mechanics. He talks in the article of “very simple physics”. What is simple is his understanding of physics. Let’s pick the rest of his quote apart piece by piece.

There is a formula for kinetic energy. That formula is one half mass times velocity squared. 

That’s the simple part.

The more important part of that equation is the velocity squared.

Well, no, all factors are important. If the ‘half’ were a ‘one’ then the object would be carrying double the kinetic energy. As it would if the object had twice the mass. A dry old football weighed more than a dry new one, and a waterlogged old football more still. As a real tennis player, I know (from painful experience) that I’d much rather be hit a lawn tennis ball than a real tennis ball (same size and coating but 25% heavier), travelling at the same velocity.

We know players are bigger, stronger and kicking the ball faster

Do we? Perhaps someone should tell Lionel Messi (5’ 6”) that he’s not big enough to have won the FIFA ballon d’or five times. Now, it’s possible that the likes of Ronaldo and Bale can get the same or slightly greater energy (remember, it’s the energy that counts; Grey falls into his own trap that velocity is the only significant factor) into a football than Charlton or Lorimer could, but…

So the amount of energy in the ball is maybe even more

…I’m certain that the balls blasted by those veterans carried more energy after 20 yards, which is because a heavier object is slowed less by air resistance. Think of the fastest baseball pitcher picking up a golf ball and a ping pong ball in the same hand and hurling them at you, without bat or protective clothing, from 60’. The ping pong ball probably wouldn’t reach you; but you’d know all about the golf ball hitting you in the head (assuming you were still conscious). A little knowledge, of mechanics in the case of Dr Grey, is a dangerous thing.

There is still energy in the new balls to wobble the brain inside the cranium

Maybe, but clearly not nearly as much; the old balls were both heavier (the more so when wet) and travelling faster under most circumstances at the point of impact with a head; both variables acting to increase kinetic energy.

Then there’s a factor that Grey neglects completely. Not all of the kinetic energy of the ball is transferred to the head in the collision. Often, the player will want as much of its kinetic energy as possible to be retained, augmented by energy imparted by the player (sometimes, the player will want to absorb the ball’s energy to cushion it into the path of a teammate—he will aim to use the neck to transmit the energy through his frame, rather than present a static skull). A football is designed to compress and rebound on impact, to retain most of it’s kinetic energy, but at the loss of the energy required to do the compression. A waterlogged leather football loses most of its compressibility. It’s more like heading a cannonball. Thus the kinetic energy gets transformed into compression waves in the jelly jammed into the skull. You really had to be there.

It would be a shame to throw the baby out with the bath water: to so terrify parents with slight risks attendant upon an engrossing, physical game that they’d rather have their offspring simulating football on the X-box, risking RSI of the thumbs and Type 2 diabetes.